CN111608315A - Fire-resistant composite floor slab and fire resistance testing method thereof - Google Patents

Fire-resistant composite floor slab and fire resistance testing method thereof Download PDF

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CN111608315A
CN111608315A CN202010514154.8A CN202010514154A CN111608315A CN 111608315 A CN111608315 A CN 111608315A CN 202010514154 A CN202010514154 A CN 202010514154A CN 111608315 A CN111608315 A CN 111608315A
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fire
resistant
floor slab
composite floor
concrete
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CN111608315B (en
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彭耀光
石永久
余香林
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Baianli Steel Structure Application Science & Technology Co ltd
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Baianli Steel Structure Application Science & Technology Co ltd
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    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00—Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/16—Load-carrying floor structures wholly or partly cast or similarly formed in situ
    • E04B5/32—Floor structures wholly cast in situ with or without form units or reinforcements
    • E04B5/36—Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor
    • E04B5/38—Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor with slab-shaped form units acting simultaneously as reinforcement; Form slabs with reinforcements extending laterally outside the element
    • E04B5/40—Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor with slab-shaped form units acting simultaneously as reinforcement; Form slabs with reinforcements extending laterally outside the element with metal form-slabs
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/64—Insulation or other protection; Elements or use of specified material therefor for making damp-proof; Protection against corrosion
    • E04B1/642—Protecting metallic construction elements against corrosion
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
    • E04B1/92—Protection against other undesired influences or dangers
    • E04B1/94—Protection against other undesired influences or dangers against fire
    • E04B1/941—Building elements specially adapted therefor
    • E04B1/942—Building elements specially adapted therefor slab-shaped
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N25/00—Investigating or analyzing materials by the use of thermal means
    • G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
    • G01N25/22—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures
    • G01N25/28—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures the rise in temperature of the gases resulting from combustion being measured directly
    • G01N25/30—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures the rise in temperature of the gases resulting from combustion being measured directly using electric temperature-responsive elements
    • G01N25/32—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures the rise in temperature of the gases resulting from combustion being measured directly using electric temperature-responsive elements using thermoelectric elements

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Abstract

The invention discloses a fire-resistant composite floor slab and a fire resistance testing method thereof. The fire-resistant composite floor slab comprises a fire-resistant steel or fire-resistant weather-resistant steel profiled floor bearing plate with a profiled rib of a closed hollow part and concrete poured on the floor bearing plate, wherein the floor bearing plate is made of a base material without a coating and a film, the upper surface of the poured concrete is leveled for maintenance and is combined with the floor bearing plate into a whole, the whole floor slab is used as the fire-resistant composite floor slab, the deformation at the initial stage of a fire disaster is delayed, the amplitude is reduced, the concrete does not collapse at the middle-stage high temperature stage, the deformation force and the integral composite effect are kept, the bonding performance between the concrete and the floor bearing plate is not loosened after the fire disaster, the deformation recovery degree and the residual bearing force are higher than. The test method comprises the steps of testing the mechanical property of the material, testing the shearing-bonding property and the fire resistance of the fire-resistant composite floor slab, testing the residual bearing property and the shearing-bonding property after fire, synthesizing a new shearing-bonding-coefficient, and concluding the fire safety coefficient.

Description

Fire-resistant composite floor slab and fire resistance testing method thereof
Technical Field
The invention relates to a fire-resistant composite floor slab; the invention also relates to a method for testing the fire resistance of the fire-resistant composite floor slab.
Background
In recent years, with the development of high-rise buildings, steel-concrete composite boards are increasingly popularized and applied. The so-called composite slab is a structural form which combines the materials and structural characteristics of steel and concrete into a whole to work together, and the profiled steel sheet composite slab is mostly used at present. The profiled steel sheet-concrete composite floor slab belongs to a bearing horizontal partition member in a composite structure and is widely applied to high-rise steel structures and multi-layer steel structure factory buildings. The profiled steel sheet-concrete combined floor system is divided into two conditions in practical engineering: one is that the profiled steel sheet is only used as a template for concrete pouring during construction, and the function of the profiled steel sheet is not considered in the normal use process; the other is that the profiled steel sheets and the concrete are formed into a whole and are stressed together by the combined action (shear connection) between different materials. The first one is equivalent to common concrete floor slab, and has no 'combination' function, so that the later in engineering application and research is more, and its profiled steel plate is equivalent to longitudinal tension steel bar in common concrete floor slab, so that the profiled steel plate composite slab is a very reasonable structure form, and can fully utilize the advantages of good tensile strength of steel and good compression strength of concrete according to the position and characteristics of all its component parts, and possesses good seismic resistance and construction property, so that said structure can be extensively used in domestic and foreign buildings at present.
The existing profiled steel plate floor support plate is generally made of galvanized steel plates, in order to prevent rusting and corrosion, the surface of the galvanized steel plate needs to be subjected to phosphating treatment, also called as involucra treatment, phosphate involucra formation is a corrosion reaction, corrosive ingredients are stopped on the metal surface, a corrosion product is changed into the involucra by a smart method, namely, an immersed phosphate film layer is formed on the surface of a metal product, and the film layer and a metal body have good binding capacity, wear resistance and adhesion capacity to coatings. However, in a high temperature state of a fire, the galvanized steel sheet is heated to gasify the coating adhesive film and further separate the surface where the concrete and the steel are adhered, so that the concrete is cracked under high temperature load, and the composite floor slab is collapsed.
With the continuous emergence of high-rise and super high-rise buildings, the importance of fire resistance of building structures is increasingly prominent. The profiled steel plate floor support plate is generally provided with a profile rib in the middle, the profile rib is generally divided into a closed profile rib and an open profile rib, the bottom of the open profile rib is provided with a large opening, the opening leads the interior of the profile rib to be directly contacted with ambient air, once a fire disaster occurs, the lower part of the floor support plate can be contacted with open fire and high-temperature air to conduct heat rapidly, the strength of a steel structure can be reduced rapidly along with the rise of temperature, the yield strength is reduced, the elastic modulus is reduced obviously, the subsequent temperature deformation and stress distribution can be influenced, the temperature of the lower surface of the floor support plate with the open profile rib and the temperature of the top of the rib can reach about 600 ℃ when the floor support plate is subjected to fire for 30min, the structural stability of a building is influenced finally, the structural stability of the building can not reach. In order to prevent the steel structure from being damaged by fire, the steel structure is generally treated by adopting fireproof coating and fireproof shielding, but the treatment not only wastes labor and materials, but also pollutes the environment, and even the fire protection treatment is generally not carried out on the special steel structures such as floor bearing plates at present, so the fire safety hidden danger exists.
The fire-resistant design of the structure is carried out according to the current national standard, and the fire-resistant grade of the structure needs to be determined firstly. According to the latest national standard, namely the building design fire protection code GB 50016-2014, various buildings have different fire resistance grades due to different properties and required safety ratings (related to building height, floor number and the like). The refractory limits correspond to the required refractory limits (refractory times) for different structures and components. The floor slab is used as a bearing component with horizontal separation function and needs to meet three conditions of heat insulation (back fire surface temperature limit), integrity, stability and bearing capacity (deformation condition limit).
However, the fire-resistant design of the pressed steel plate-concrete composite floor slab by the relevant national and international regulations is still based on the fire-resistant time measured by a fire-resistant detection test on a few test pieces under a given load. And the factors influencing the fire resistance of the composite floor are many. Because the load level born by the floor in the actual building is various and different in size, the load level is probably different from the load level applied by the test; and the structural form of a floor system in an actual building is greatly different from a test piece of a fire resistance test, and the factors can cause that the fire resistance time of the floor system in the actual building is different from the result measured by the test. The fire-resistant design method of the profiled steel sheet-concrete composite floor slab in the current specifications of China mainly comprises 'fireproof technical specification of building steel structure' and 'design and construction specification of the composite floor slab', and the European specification regulates the fire-resistant design of the composite floor slab in the second part of EC 4. However, these specifications are based on the general open-type or reduced-type profiled steel sheets, and the fire-resistant design of the closed-type profiled steel sheet-concrete composite floor using the novel fire-resistant steel or fire-resistant weathering steel is not specified or specified. The improvement of fire resistance brought by the novel structural form is not fully recognized and incorporated into the standard design thought, and the fire resistance design method for the structural component needs to be deeply researched and proposed again.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide the fire-resistant composite floor slab which has strong fire resistance, high safety, good deformation performance and strong cooperative working capability.
The invention also provides a method for testing the fire resistance of the fire-resistant composite floor slab.
The technical scheme adopted by the fire-resistant composite floor slab is as follows: the fire-resistant composite floor slab comprises a fire-resistant steel or fire-resistant weather-resistant steel profiled floor bearing plate and concrete, the profiled floor support plate comprises a profiled rib with a closed hollow part, the profiled floor support plate is made of a substrate without a coating and a membrane, the concrete is poured on the profiled floor support plate, after the concrete is poured, the upper surface of the concrete is strickled off and maintained, the floor slab is combined with the profiled floor bearing plate into a whole and is used as a fire-resistant composite floor slab, when the fire-resistant composite floor slab bears normal load, the deformation is delayed in the initial stage of the fire, the deformation amplitude is reduced, the collapse is not generated in the middle-stage high-temperature stage of the fire, the stable deformation capability and the integral combination effect are maintained, the temperature is recovered to the room temperature after the fire, the bonding performance between the concrete and the profiled floor support plate is maintained and not loosened, the deformation recovery degree and the residual bearing capacity are both higher than 50 percent, and the combined effect and the integrity are still realized.
The fire-resistant composite floor slab further comprises an anti-cracking reinforcing mesh, the anti-cracking reinforcing mesh is formed by adopting steel bars for building structures or fire-resistant steel bars or fire-resistant weather-resistant steel bars through cross spot welding, the anti-cracking reinforcing mesh is erected on a compression area of the concrete above the profiling floor bearing plate, and the anti-cracking reinforcing mesh and the concrete are combined into a whole after the concrete is poured.
The thickness of the concrete above the anti-cracking reinforcing mesh is not less than 20 mm.
The profiled floor support plate is made of fire-resistant steel or fire-resistant weather-resistant steel through integral rolling forming and comprises a bottom plate, a first buckling part and a second buckling part which are respectively arranged at the left end and the right end of the bottom plate, and a plurality of profiled ribs arranged at the middle part of the bottom plate at intervals, wherein the first buckling part and the second buckling part of the profiled floor support plate are connected in a matched and buckled mode.
The profile rib comprises a lower vertical rib and an upper closed hollow part.
The cross section of the closed hollow part is triangular or regular polygonal or circular.
And longitudinal or transverse bottom plate reinforcing ribs protruding upwards are arranged on the bottom plate at intervals.
And longitudinal reinforcing ribs or concave-convex indentations are arranged on the profile ribs.
The technical scheme adopted by the fire resistance testing method of the fire-resistant composite floor slab is as follows: the method for testing the fire resistance of the fire-resistant composite floor slab comprises the following steps:
(A) respectively carrying out material mechanical property test on the fire-resistant steel or fire-resistant weather-resistant steel adopted by the profiling floor support plate and the concrete adopted by the fire-resistant composite floor slab: the mechanical property indexes of the fire-resistant steel or the fire-resistant weathering steel at normal temperature and high temperature are measured by adopting a standard tensile test, a stress-strain constitutive model is obtained, and then the mechanical property indexes of the fire-resistant steel or the fire-resistant weathering steel, such as the elastic modulus, nominal yield strength, tensile strength, compressive strength, yield ratio, elongation after fracture and the like, are obtained, so that the fire-resistant steel or the fire-resistant weathering steel can meet various requirements of the fire-resistant steel or the fire-resistant weathering steel; measuring the standard cubic compressive strength of the concrete by adopting a standard test method so as to reflect the basic mechanical properties of the concrete of the same batch;
(B) pouring and maintaining the fire-resistant composite floor slab, carrying out a shearing-bonding performance test on the fire-resistant composite floor slab, so as to measure the shear bonding coefficient of the pressed floor bearing plate and the concrete interface, obtain the longitudinal shear bearing capacity of the fire-resistant composite floor slab through regression, obtain the mechanical properties of the fire-resistant composite floor slab, such as the longitudinal shear bearing capacity, the longitudinal sliding characteristic, the flexural deformation characteristic, the compression failure mode and the like at normal temperature, and regression analysis is carried out to obtain empirical coefficients m and k, a calculation formula of the longitudinal shearing bearing capacity of the fire-resistant composite floor slab and a related curve, researching a cooperative working mechanism between the profiling floor bearing plate and the concrete according to mechanical property indexes, crack development conditions and deformation characteristics of upper and lower surfaces and internal key parts of the fire-resistant composite floor slab, and comparing the difference of the stress performance of the composite floor slab under the actions of normal temperature and high temperature;
(C) pouring the fire-resistant composite floor slab and maintaining, and carrying out fire simulation fire resistance performance test on the fire-resistant composite floor slab to simulate and obtain the fire resistance performance of the fire-resistant composite floor slab when an actual fire disaster occurs: judging the failure and damage control conditions of the fire-resistant composite floor through a standard temperature rise process and a standard temperature rise curve in the furnace, acquiring the bonding displacement data, the fire resistance limit, the damage form, the mid-span deflection, the end slippage, the crack distribution, the stress strain distribution, the temperature change at the interface of the profiled floor bearing plate and the concrete, the average temperature rise and the maximum temperature rise of the fire-receiving surface and the back fire surface, the temperature distribution rules of the fire-receiving surface, the back fire surface and the key parts inside the concrete and the temperature change rule of the concrete inside along the plate thickness direction, combining the test result with the finite element result and parametric analysis, and judging and determining the main influence factors influencing the fire resistance performance of the fire-resistant composite floor;
(D) after the fire test is finished, closing the flame spray nozzle, then opening the exhaust system, entering a cooling stage, slowly cooling to 50 ℃ of the furnace temperature, detaching the load, keeping data acquisition all the time until the temperature is recovered to the room temperature, measuring the rebound deformation value of the test piece, re-measuring the deformation value of the test piece after the temperature is kept at the room temperature for one day, performing the post-fire residual bearing performance test on the fire-resistant composite floor subjected to the fire simulation fire-resistant performance test, and acquiring post-fire static load, mid-span maximum deformation and final residual deformation data to obtain the post-fire residual bearing capacity and the post-fire deformation recovery degree of the fire-resistant composite floor;
(E) and comparing the displacement and deformation recovery conditions between the profiled floor bearing plate and the concrete under the conditions of high temperature of fire and after cooling to the room temperature, and carrying out shearing-bonding performance inspection at the room temperature after fire passing and cooling so as to compare the performance difference of the fire-resistant composite floor before and after the fire, synthesize new shearing-bonding coefficients m and k after the fire, and further conclude the fire safety coefficient.
In the step (C), high-temperature-resistant thermocouples are pre-buried in the concrete at the midspan part of the fire-resistant composite floor slab and at the interface between the profiled floor support plate and the concrete, close to the top surface and the bottom surface of the profiled floor support plate, so as to measure the temperature development conditions of all parts; arranging a plurality of thermocouples on the back fire surface of the fire-resistant composite floor slab to obtain the heat insulation performance index of the fire-resistant composite floor slab test piece; the thermocouples are symmetrically and uniformly arranged on the inner wall of the horizontal combustion furnace along the length direction of the furnace and are used for monitoring the temperature distribution and difference of different positions in the furnace, and the temperature rise of each part is strictly controlled within a specified range by adjusting the switch of the flame nozzle and the air supply frequency in time so as to simulate the indoor fire condition of a uniform temperature field; a pre-buried wire is led out from each thermocouple; in the temperature rising process, measuring the instantaneous temperature of the key suspicious part on the back fire surface of the refractory combined floor slab test piece by using a handheld infrared temperature detector at fixed time intervals; arranging a displacement sensor at the central point of the back fire surface of the profiled floor support plate test piece to determine the midspan deflection change process; and the displacement sensors are additionally arranged at the left and right symmetrical positions of the back fire surface of the pressed floor bearing plate test piece so as to determine and verify whether the fire-resistant composite floor slab generates integral symmetrical bending deformation in the fire receiving process.
The invention has the beneficial effects that: because the fire-resistant composite floor slab comprises the fire-resistant steel or fire-resistant weather-resistant steel profiled floor bearing plate and the concrete, the profiled floor support plate comprises a profiled rib with a closed hollow part, the profiled floor support plate is made of a substrate without a coating and a membrane, the concrete is poured on the profiled floor support plate, after the concrete is poured, the upper surface of the concrete is strickled off and maintained, the floor slab is combined with the profiled floor bearing plate into a whole and is used as a fire-resistant composite floor slab, when the fire-resistant composite floor slab bears normal load, the deformation is delayed in the initial stage of the fire, the deformation amplitude is reduced, the collapse is not generated in the middle-stage high-temperature stage of the fire, the stable deformation capability and the integral combination effect are maintained, the temperature is recovered to the room temperature after the fire, the bonding performance between the concrete and the profiled floor support plate is maintained and not loosened, the deformation recovery degree and the residual bearing capacity are both higher than 50 percent, and the combined effect and the integrity are still realized; the invention overcomes the defects and shortcomings of the prior art, the profiled floor support plate is made of a substrate without a coating and a skin membrane, and the gasification of the concrete and the coating bonding skin membrane cannot occur at a high temperature, so that the separation of a bonding interface between the concrete and steel and the burst under high-temperature loading are avoided, and small cracks after slow cooling are closed under the special effect of resilience; the refractory Steel is called FR Steel for short (Fire Resistant Steel), which makes up the weakness of common Steel, improves the strength of the Steel at high temperature, can reduce or even does not need a refractory coating after being used, is used in a naked way or simplifies coating, saves maintenance cost and cost, can display the color and style of the Steel without change, realizes the requirement of a non-coating fireproof Steel structure, has the same design as the common Steel at normal temperature, can be processed and constructed as the common Steel, has higher strength at high temperature, can ensure that the yield strength at 600 ℃ reaches two thirds of the specification value at normal temperature, improves the self-Fire resistance of the Steel, saves labor and materials, increases effective use area and reduces environmental pollution compared with adopting fireproof paint and fireproof shielding; the weather-proof and fire-resistant steel mainly adopts various alloy elements such as Cu, Ni, Cr, Si, P, Nb and the like to improve the fire-proof and weather-proof performances of the steel, although the production of the weather-proof and fire-resistant steel adopts various alloy elements to improve the cost of the steel, the common steel must be subjected to formulated protection measures when resisting fire and corrosion, the traditional protection measures such as spraying, composite coating, external protection method and the like not only prolong the construction period, improve the construction cost and increase the building weight, but also are inconvenient to construct, so the weather-proof and fire-resistant steel not only is economical and economical, but also is simple to construct and saves the construction period, has good mechanical and chemical properties, can enhance the atmospheric corrosion resistance of the weather-proof and fire-resistant steel by forming a self-protective oxide film on base metal under a certain temperature condition in the steel after adding P, Cu, Cr, Ni, Mo and … …, and avoids oxygen and moisture in the atmosphere from corroding or even rusting the steel, the steel member can resist rust and fire, so that the steel member is corrosion-resistant and has prolonged service life, can be thinned for use under the condition of meeting the structural strength, can be used in an exposed manner without being coated, thereby saving the maintenance cost and the cost, can be in direct contact with the ambient air for a long time, does not influence the use effect of the steel member, ensures the structural stability of the building, meets the requirement of the design service life of the steel member, is particularly suitable for being used in regions with high humidity and high acidity and alkalinity such as coastal regions, and can ensure the safety and the service life of the building; the invention adopts the profiled fire-resistant steel or fire-resistant weather-resistant steel floor bearing plate and concrete to form the combined floor slab by pouring and combining, makes full use of respective advantages and cooperative working capacity of the fire-resistant steel or the fire-resistant weather-resistant steel and the concrete, generates a combined effect, realizes the effect that 1+1 is more than 2, and when a fire disaster happens, the fire is seen under the common steel floor bearing plate to rapidly heat up, and the top of a vertical rib is far more than 400 ℃ even if the concrete insulates heat, so the strength performance of the material is greatly reduced, the use of the common steel floor bearing plate becomes a barrier of a combined structure, and the structure of the steel bearing plate is not improved, but the profiled fire-resistant steel or fire-resistant weather-resistant steel floor bearing plate overcomes the defects, and tests prove that the temperature of the top of the vertical rib is less than 300 ℃ after the fire is fired for 90min, and the temperature of the top of the vertical rib is less than 400 ℃ after the fire, the composite floor slab has the advantages of strong bearing capacity, good ductility, excellent fire resistance, easy repair of damage, high efficiency, environmental protection, flexible and variable forms and the like, is a novel high-performance composite floor slab, is suitable for various structural types and different key parts, is tested, is subjected to fire for 60min to 950 ℃ according to a standard temperature rise curve when bearing normal load, continuously and slowly develops floor slab deformation caused by the high-temperature action of the fire, has stable continuous deformation capacity and intact integral combination effect all the time before damage, can not collapse even if visible tiny cracks occur, has extremely strong deformation recovery capacity after being cooled to room temperature through air supply and air exhaust, has the phenomenon of closing tiny cracks, has the deformation recovery degree of the cross-middle part higher than 50 percent, the residual bearing capacity after fire is higher than 50%, the interface slippage is small, and the building has good combination effect and integrity, so that the structural stability of the building is greatly improved, the fire hazard safety hazard of the building can be reduced to the greatest extent, the structural stability of the building is ensured when and after the fire occurs, secondary disasters are avoided, and the safety and the service life of the building are ensured; through a simulated fire test, the fire-resistant composite floor slab is not easy to generate cracks generated by a common floor slab in a fire disaster and can not collapse, when the constant load is heated to the extent that the deformation of the fire-resistant composite floor slab reaches half of the damaged limit deformation, almost no cracks appear, even if the constant load is heated to the extent that the deformation of the composite floor slab reaches the damaged limit deformation, the concrete part of a tensile area at the bottom has slight cracks, the width and the depth of the cracks are also much smaller than those of the common floor slab, and even if the composite floor slab is burnt to the damaged, the floor slab can be restored or even closed due to deformation restoration, so the residual bearing performance and the safety degree after the fire disaster are very high; tests prove that the hollow closed-end profiled section with the closed cavity adopted by the fire-resistant steel or fire-resistant weather-resistant steel profiled floor deck has excellent heat insulation and temperature resistance, the safety level of the fire-resistant composite floor slab composite structure before and after fire can be greatly improved, and the high temperature resistance of the fire-resistant steel or fire-resistant weather-resistant steel can be compared with that of the existing galvanized plate or other steel composite floor slabs, so that the conclusion can be drawn: (1) in the initial stage of fire, the temperature rise deformation of the fire-resistant composite floor slab is delayed, and the deformation is greatly reduced, so that the early safe evacuation time of fire can be prolonged, (2) in the middle high-temperature stage of fire, the contrast deformation amplitude is greatly improved, the fire-resistant composite floor slab always has stable continuous deformation capability and intact integral composite effect before damage, even if micro cracks visible to the naked eye appear, the collapse can not occur, the safety level in the fire fighting and disaster relief process can be improved, (3) after fire, the bonding performance can be maintained between the concrete and the profiling floor support plate without loosing, the cracks of the fire-resistant composite floor slab are closed, the deformation recovery degree of the middle part is higher than 50%, the residual bearing capacity after fire is higher than 50%, the interface slippage is small, the composite effect and the integrity are still provided, so that the damage after recovery is small, the safety level after fire disaster can be improved, so that the structural safety performance of the building is greatly improved; therefore, the fire-resistant composite floor slab has the advantages of strong fire resistance, high safety, good deformation performance and strong cooperative working capability, is slow in deformation after a fire disaster occurs, is not easy to crack and collapse, is quick in deformation recovery, and is small in damage to a combined effect.
In addition, the method for testing the fire resistance of the fire-resistant composite floor slab is specially carried out aiming at a novel composite structure form of a profiled steel plate with a fire resistance function, the improvement of the fire resistance brought by the novel structure form is comprehensively tested and verified, the surface bonding verification of the concrete and the profiled floor support plate after fire passing is increased through a specific innovative detection method, the index of the structure maintaining effectiveness is obtained, the verification coefficient can be fed back to the original calculation formula to form a post-disaster structure safety calculation method, namely post-disaster structure evaluation, a path is provided for the deep system research of the fire resistance design method of the members, so that on the basis of the traditional composite structure system, the method is favorable for perfecting and optimizing the cooperative work mechanism of the high-performance composite floor slab, other horizontal members and vertical members, and a reasonable arrangement scheme of the novel structure system is provided, The stress mechanism, the fire-resistant failure mechanism and the performance design method are combined with the demonstration application of key building engineering, and a novel high-rise building combined structure system is further perfected.
Drawings
FIG. 1 is a schematic cross-sectional view of a refractory composite floor slab according to a first embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view of a refractory composite floor slab according to a second embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a fire-resistant composite floor slab according to a second embodiment of the present invention before fire resistance testing;
FIG. 4 is a schematic cross-sectional view of a refractory composite floor slab according to a third embodiment of the present invention;
fig. 5 is a schematic sectional view of a refractory composite floor slab according to a fourth embodiment of the present invention.
Detailed Description
The first embodiment is as follows:
as shown in fig. 1, the fire-resistant composite floor slab of the present embodiment includes a fire-resistant steel profiled floor slab 10 and concrete 20, the profiled floor slab 10 includes a profiled rib 4 with a closed hollow portion, the profiled floor slab 10 is made of a non-coated and non-coated base material, the concrete 20 is poured on the profiled floor slab 10, after the concrete 20 is poured, the upper surface of the concrete is scraped flat and maintained, and then the concrete and the profiled floor slab 10 are combined into a whole, and the whole is used as a fire-resistant composite floor slab; the profiled floor support plate 10 is made of fire-resistant steel through integral rolling forming and comprises a bottom plate 1, a first buckling part 2 and a second buckling part 3 which are respectively positioned at the left end and the right end of the bottom plate 1, and a plurality of profiled ribs 4 which are arranged at the middle part of the bottom plate 1 at intervals, wherein the first buckling part 2 and the second buckling part 3 of the adjacent profiled floor support plate 10 are matched and buckled, the first buckling part 2 and the second buckling part 3 after buckling connection are consistent with the profiled ribs 4, so that the profiled floor support plate has the same function and structural characteristics as the profiled ribs 4, the whole profiled ribs are not easy to fall off, the profiled ribs 4 comprise vertical ribs with the lower parts jointed and closed hollow parts at the upper parts, the jointed vertical ribs 4 can make the bottom of the plate flat and beautiful, fire is prevented from directly entering the profiled ribs 4, the profiled floor support plate 10 has high strength and better fire resistance, the cross section of the closed hollow part is an isosceles triangle, certainly, other shapes can be adopted, the closed hollow part can enhance the bonding strength between the profiled floor bearing plate 10 and the concrete 20, further, the stability of the composite floor structure is enhanced, the bottom plate 1 is provided with upward raised longitudinal bottom plate reinforcing ribs 5 at intervals, certainly, transverse bottom plate reinforcing ribs are also provided for enhancing the strength and the deformation recovery capability of the bottom plate 1, the reinforcing ribs 5 are trapezoidal, certainly, other shapes can be adopted, the bottoms of the vertical ribs of the profile ribs 4 are provided with opposite longitudinal reinforcing ribs 6 for achieving the purpose of reinforcement, small openings are reserved at the bottoms of the longitudinal reinforcing ribs 6 for enhancing the bending resistance capability and the deformation recovery capability, certainly, concave-convex impressions can be arranged at intervals on the side walls of the closed hollow part of the profile ribs 4 according to actual conditions, the strength of the pressed floor bearing plate 10 is increased, the binding force of the pressed floor bearing plate 10 and the concrete 20 can be increased, and the overall structural strength of the fire-resistant composite floor slab is improved, wherein the plate type of the pressed floor bearing plate 10 is derived from the prior patent 'CN 200730008188.5 floor bearing plate' of the applicant; when the fire-resistant composite floor slab bears normal load, the deformation of the fire at the initial stage is delayed, the deformation amplitude is reduced, the fire does not collapse at the high-temperature stage in the middle stage, the stable deformation capacity and the integral composite effect are kept, the temperature is recovered to the room temperature after the fire, the bonding performance between the concrete and the profiled floor support plate is kept not to be loosened, the deformation recovery degree and the residual bearing capacity are both higher than 50%, and the composite effect and the integrity are still achieved.
The method for testing the fire resistance of the fire-resistant composite floor slab comprises the following steps:
(A) respectively carrying out material mechanical property tests on the fireproof steel adopted by the profiling floor support plate 10 and the concrete 20 adopted by the fireproof composite floor slab: standard tensile test is adopted to determine the temperature of the refractory steel at normal temperature and high temperatureObtaining a stress-strain constitutive model according to the mechanical property indexes, and further obtaining mechanical property indexes such as elastic modulus, nominal yield strength, tensile strength, compressive strength, yield ratio, elongation after fracture and the like of the refractory steel so as to enable the refractory steel to meet various requirements of the refractory steel; the tensile test is carried out on a high-temperature unidirectional tensile testing machine to obtain the stability and the accuracy of the test result, and the stress-strain relation curve of the elastic stage is measured by adopting a unidirectional strain gauge; the results of the normal temperature tensile test of the three samples show that except for different total fracture elongation at the failure stage, the stress-strain curves of the three samples before reaching the tensile strength are basically superposed, which shows that the test results have high stability and consistency, the discreteness of the constitutive model of the fire-resistant structural steel is very small, the steel is similar to high-strength steel, the stress-strain curve has no obvious yield platform, and the elongation strength R corresponding to 0.2 percent plastic strain is takenp0.2As the nominal yield strength, the test result shows that the mechanical performance indexes such as the nominal yield strength, the tensile strength, the yield ratio and the elongation after fracture of the fire-resistant steel adopted by the pressed floor deck 10 all meet the requirements of GB/T19879-2015 on Q390GJ and GB/T28415-2012 on Q390FR, and in addition, the tensile strength, the yield ratio and the elongation after fracture are obviously improved compared with the specifications, which shows that the fire-resistant steel has good strength and deformability;
measuring the standard cubic compressive strength of the concrete by adopting a standard test method so as to reflect the basic mechanical properties of the concrete of the same batch; according to GB/T50081-2002 Standard test method for mechanical properties of common concrete, a cube with the side length of 150mm is manufactured, the cube is cured to the age of 28d under the condition of standard curing (the temperature is 20 +/-2 ℃, and the relative humidity is more than 95 percent), and the ultimate compressive strength measured by using a standard test method is called the compressive strength of the concrete standard cube. According to the provisions of GB 50010-2010 concrete structure design specifications, in the overall distribution of cubic ultimate compressive strength, the compressive strength of a cubic test piece with 95% strength guarantee rate is called as a concrete cubic compressive strength standard value, the concrete cubic compressive strength standard value is obtained by subtracting 1.645 times of compressive strength standard deviation from the cubic compressive strength average value, the compressive strength with 95% guarantee rate measured according to a standard experimental method is used as a concrete strength grade, the concrete of all composite floor slabs is cast in situ in an open air environment, and the concrete standard cubic compressive strength test is carried out on an electro-hydraulic pressure tester;
(B) pouring and maintaining the fire-resistant composite floor slab, carrying out a shearing-bonding performance test on the fire-resistant composite floor slab, so as to measure the shear bonding coefficient of the interface between the profiled floor support plate 10 and the concrete 20, obtain the longitudinal shear bearing capacity of the fire-resistant composite floor slab through regression, obtain the mechanical properties of the fire-resistant composite floor slab, such as the longitudinal shear bearing capacity, the longitudinal sliding characteristic, the flexural deformation characteristic, the compression failure mode and the like at normal temperature, and regression analysis is carried out to obtain empirical coefficients m and k, a calculation formula of the longitudinal shearing bearing capacity of the fire-resistant composite floor slab and a related curve, according to the mechanical property index, the crack development condition and the deformation characteristics of the upper surface, the lower surface and the internal key parts of the fireproof composite floor slab, the cooperative working mechanism between the profiling floor bearing plate 10 and the concrete 20 is researched and used for comparing the difference of the stress performance of the composite floor slab under the action of normal temperature and high temperature; the test adopts a self-made gantry counterforce steel frame (see the prior patent application CN201710107250.9 of the applicant in detail, a structural plate stress deformation detection device) to be matched with a 60-ton high-precision servo jack for pressurization, and static loading and dynamic loading tests are respectively carried out on the test piece according to relevant regulations of composite floor tests in European standard 'Eurocode 4: Design of composite steel and composite structures-Part 1-1: General rules and rules for building' (BS EN 1994-1-1: 2004) and B.3 Testing of composite floor slabs so as to determine the ultimate bearing capacity of the composite floor; the test phenomenon shows that under the action of step-by-step static load, the midspan deformation is approximately linearly increased along with the increase of external load, after 0.1mm end part sliding is generated at one end or two ends of all closed type composite floor slabs, the closed type composite floor slabs can still continuously bear larger load, the midspan deflection is larger than L/50 when the floor slabs reach the limit bearing capacity, the final damage form is ductile damage, the longitudinal sliding between the profiled floor bearing plate 10 and the concrete 20 interface is slowly increased before the floor slabs reach the damage load, but the longitudinal sliding is far smaller than the maximum limit bearing capacityThe end part slippage when the bearing capacity reaches the limit, after 5000 times of dynamic cycles, the test piece has larger span residual deformation, the minimum residual deformation also reaches 20mm, after the test piece reaches the limit load, the span deflection is mostly more than 100mm, but the profiled steel sheet and the concrete are not completely separated, the interface bonding property is not completely lost, the composite effect is still good, when the floor slab in the static loading stage reaches the breaking load, the interface has partial slippage, but the steel plate and the concrete of the floor bearing plate do not fall off, the longitudinal sliding is continuously increased along with the increase of the load until the ultimate bearing capacity of the composite floor slab is reached, therefore, the composite floor slab has strong deformation capacity, the combination effect between the two materials of the profiled floor support plate 10 and the concrete 20 is very obvious, and the test result shows that the difference between the destructive load defined by EC4 and the ultimate bearing capacity is large; tests also show that the composite floor slab basically generates longitudinal shear cohesive failure, only a few test pieces with long plate span and large shear span ratio generate approximate integral bending failure, but shear main cracks still appear at the pressure bearing part of the four-point, so the shear cohesive failure can be considered to occur, the closed profiled steel plate-concrete composite floor slab has extremely strong deformability and elasticity restorability, the mid-span deflection continuously and stably increases along with the increase of external load and exceeds the mid-span static deformation control condition (L-span static deformation control condition)nThe composite floor still has strong ductility, and for a composite floor test piece only bearing static gradual loading, the external force is removed before the destructive load is reached, the bending deformation of the composite floor can be rapidly recovered, and the residual deformation is small, so that the good combination effect between the closed profiled floor bearing plate 10 and the concrete 20 is further verified; the contrast test shows that all open type floor slab test pieces are subjected to brittle failure, the combination effect between the profiled steel plates and the concrete of the floor slab test pieces is poor, once the interface generates longitudinal sliding, cracks rapidly expand, the profiled steel plates and the concrete integrally slide, the bonding performance between the interfaces is poor, the difference between the failure load defined by EC4 and the ultimate bearing capacity is small and basically within 5kN, the rigidity of the open profiled steel plates-concrete combined floor slab is large, the ductility is poor, and the vertical load does not reach the extreme bearing capacity of the floor slabBefore the bearing capacity is limited, the mid-span deflection is slowly increased approximately linearly along with the increase of external load, but the deflection value is always far smaller than the mid-span static deformation control condition (L)n50), when the vertical load reaches a destructive load, the floor immediately generates brittle failure, the load suddenly drops due to Gabeng type cracking and deformation of the combined floor, intermittent sliding and cracking occur when the load is continuously loaded, mid-span deflection is continuously increased, the number and width of cracks are continuously increased and expanded until the bonding force is completely lost, and the combined floor collapses in a waist-chopping manner;
(C) pouring the fire-resistant composite floor slab and maintaining, and carrying out fire simulation fire resistance performance test on the fire-resistant composite floor slab to simulate and obtain the fire resistance performance of the fire-resistant composite floor slab when an actual fire disaster occurs: judging the failure and damage control conditions of the fire-resistant composite floor through a standard temperature rise process and a standard temperature rise curve in the furnace, acquiring the bonding displacement data, the fire resistance limit, the damage form, the mid-span deflection, the end slippage, the crack distribution, the stress strain distribution, the temperature change at the interface of the profiled floor bearing plate 10 and the concrete 20, the average temperature rise and the maximum temperature rise of the fire-receiving surface and the back fire surface, the temperature distribution rules of the fire-receiving surface, the back fire surface and the internal key parts and the temperature change rule of the concrete along the plate thickness direction, combining the test result with the finite element result and parametric analysis, and judging and determining the main influence factors influencing the fire resistance performance of the fire-resistant composite floor;
in this step, the pouring manner of the composite floor slab is the same as that of the composite floor slab subjected to the shear test in the step (B), except that high-temperature-resistant thermocouples 9 (refer to fig. 3) are arranged and embedded in the concrete 20 at the mid-span portion of the refractory composite floor slab and at the interface between the profiled floor deck 10 and the concrete 20 and close to the top surface and the bottom surface of the profiled floor deck 10 before and during pouring of the refractory composite floor slab to measure the temperature development conditions of each portion, specifically, before pouring of concrete, the high-temperature-resistant thermocouples 9 are arranged at the rib tops, the rib middles, the rib bottom corners and the slab bottom center positions of the mid-span cross section of the profiled floor deck 10, and the arrangement manner is as follows: firstly, grinding and polishing the temperature measuring point, then wiping the temperature measuring point clean by alcohol, then connecting a high-temperature embedded line to a temperature sensing copper sheet, then adhering the temperature sensing copper sheet on the temperature measuring point by 502 glue and a high-temperature aluminum foil adhesive tape and flattening the temperature sensing copper sheet, and finally covering a layer of fire-proof mud on the high-temperature aluminum foil adhesive tape to fix the measuring point and prevent a thermocouple from being damaged when concrete is poured and vibrated; arranging a plurality of thermocouples 9 on the back fire surface of the fire-resistant composite floor slab to obtain the heat insulation performance index of the fire-resistant composite floor slab test piece; the thermocouples 9 are symmetrically and uniformly arranged on the inner wall of the horizontal combustion furnace along the length direction of the furnace and are used for monitoring the temperature distribution and difference of different positions in the furnace, the temperature rise of each part is strictly controlled within a specified range by adjusting the switch of a flame nozzle and the air supply frequency in time so as to simulate the indoor fire condition of a uniform temperature field, the combustion is carried out by supplying coal gas and oxygen, and ideal stable air pressure is provided by using ventilation and exhaust pipelines so as to simulate the indoor real fire condition; a pre-buried wire is led out from each thermocouple 9; in the temperature rising process, measuring the instantaneous temperature of the key suspicious part on the back fire surface of the refractory combined floor slab test piece by using a handheld infrared temperature detector at fixed time intervals; arranging a displacement sensor at the central point of the back fire surface of the test piece of the profiling floor support plate 10 to determine the midspan deflection change process; the displacement sensors are additionally arranged at the left and right symmetrical positions of the back fire surface of the test piece of the profiling floor bearing plate 10 to determine and verify whether the fire-resistant composite floor slab generates integral symmetrical bending deformation in the fire receiving process; floor load is simulated by uniformly distributing bundled and bulked refractory bricks, the load levels comprise 2kPa, 3kPa, 3.14kPa, 5kPa, 7.2kPa and 10kPa (the self weight of the floor slab is not included), and most floor load working conditions given in the specification are basically covered;
under the actual fire condition, the mid-span deflection and the deformation rate caused by the self-weight of the floor slab, the floor load and the high-temperature action have great significance for evaluating the fire resistance of the composite floor slab, and the test shows that the mid-span deflection change trend of the composite floor slab in the standard temperature rise process can be divided into three stages:
the first stage is as follows: in the initial temperature rise stage, the deformation of the composite floor slab is increased rapidly, because the temperature rise rate of a standard temperature rise curve in the initial stage is quite large, for a closed type composite floor slab, the temperature field in the furnace is distributed basically and uniformly in the range of 10-20 min after being fired, and for an open type composite floor slab, the temperature field in the furnace is distributed basically and uniformly in the range of 5-10 min after being fired, before the temperature in the furnace is not distributed uniformly, the non-uniform temperature field along the thickness direction of the composite floor slab causes the integral bending deformation of the composite floor slab, and the deformation caused by the temperature gradient is thermal deformation, so the deformation rate is increased rapidly in a short time (within a few seconds to half minutes), and then is reduced rapidly to enter a fluctuation stage;
and a second stage: for a closed composite floor, when the composite floor is fired for about 20min (about 10min for an open composite floor), the midspan deformation of the composite floor is steadily increased, the deformation rate is basically maintained at a fixed value, small amplitude fluctuation appears and lasts for a long time, but the deformation rate can generate more pulse-shaped fluctuation due to local instability in the fuel supply and combustion processes, the midspan flexibility value of the composite floor at the stage comprises thermal deformation and mechanical deformation, the latter is mainly caused by the reduction of the elastic modulus, yield strength and tensile strength of materials, and the deformation rate at the stage is smaller along with the increase of the thickness of the composite floor;
and a third stage: the deformation rate of the composite floor is gradually increased until the composite floor is damaged due to the fact that the composite floor reaches the fire resistance limit, the temperature rise of the fire-exposed surface of the composite floor is high at the stage, the mechanical property of a bottom plate of a profiled floor support plate is rapidly reduced, the interface of concrete and the profiled floor support plate longitudinally slides, the combined action between the concrete and the profiled floor support plate is weakened, new vertical cracks continuously appear in a tension area of the concrete under the action of vertical load and high temperature, the concrete continuously extends towards a compression area, the height of an effective compression area is continuously reduced, the deformation is continuously increased, the overall rigidity and the strength of the composite floor are obviously reduced, and the net bag effect provided by the profiled floor support plate 10 is not suddenly collapsed (the open type composite floor is damaged and suddenly collapsed);
tests show that under the action of fire, the composite floor slab has the following characteristics:
(1) the temperature field is not uniformly distributed. Different from a single steel structure, the combined structure mainly comprises two materials, namely steel and concrete, and the thermal conductivity coefficient, specific heat capacity and other thermal parameters of the steel and the concrete are greatly different, so that the temperature field of the section of the member is unevenly distributed under the action of fire;
(2) the rigidity and the strength of the material are degraded. Under the action of high temperature, the constitutive models of steel and concrete are changed, and the rigidity and the strength are greatly reduced;
(3) the boundary constraint condition of the component under the action of heat has great influence on the bearing capacity;
(4) when a fire disaster occurs, the strength and rigidity of the shearing and bonding action of the profiled floor support plate 10 and the concrete 20 are reduced at high temperature; when the fire duration reaches the fire resistance limit of the composite floor slab, the profiled floor support plate 10 and the concrete 20 are not peeled off, and still have a strong combination effect; under the action of fire (high temperature), the fireproof composite floor still has good stress performance and fireproof performance;
(5) the deformation of the fire-resistant composite floor slab is increased under the action of fire, but the tensile force can be provided to form a film effect, so that the integral bearing capacity of the member under the condition of large deflection is increased;
(6) for the closed composite floor, the longitudinal slippage of the interface between the profiled floor support plate 10 and the concrete 20 after the damage is not large and is within 10mm, and the longitudinal slippage of the closed composite floor after the fire damage is related to the load level and the floor thickness: for the composite floor slab applying the same load level, the larger the thickness is, the smaller the longitudinal slippage basically shows; for the composite floor slab with the same thickness, the higher the applied load level is, the greater the longitudinal slippage basically shows;
by carrying out experimental study and theoretical analysis on the fire resistance of 32 closed, necking and open profiled steel sheet-concrete composite floors based on the fire-resistant profiled steel profiled floor deck, the following conclusions can be obtained:
(1) the fire resistance limit of the closed composite floor slab with the same parameters is obviously higher than that of the necking composite floor slab, which shows that the fire resistance of the closed composite floor slab is obviously superior to that of the necking composite floor slab; the necking type composite floor slab is obviously higher than the opening type composite floor slab;
(2) the influence of the thickness of the floor slab on the fire resistance is large, and for the composite floor slab with the same plate type, the fire resistance limit is obviously improved along with the increase of the thickness of the floor slab;
(3) the fire resistance limit of all floor slab test pieces is high, failure damage is controlled by mid-span deflection, and when the floor slabs are damaged, the maximum temperature rise and the average temperature rise of the back fire surface do not exceed the standard limit values, so that the composite floor slabs based on the fire-resistant structural steel have excellent fire resistance;
(5) the concrete temperature rise in the closed type composite floor slab and the temperature rise at the closed position are slowly increased, the maximum temperature rise at the closed position and the rib top position do not exceed 300 ℃, the concrete temperature rise in the closed type composite floor slab is faster than that of the closed type floor slab, the maximum temperature rise at the rib top position of the profiled steel sheet can reach more than 500 ℃, and the heat insulation performance is poorer than that of the closed type floor slab;
(6) when the floor slab of the necking type and the floor slab of the closing type fail and break, both ends of the steel plate generate a small amount of approximately symmetrical slippage, and the steel plate is not peeled or shed from the concrete;
in addition, the test also verifies that: the bond stress between the closed profiled floor support plate 10 and the concrete 20 is larger, the profiled floor support plate 10 and the concrete 20 are not easy to separate in the bearing process, and the longitudinal shear resistance is enhanced; the temperature rise process of the pressed floor support plate 10 wrapped in the concrete 20 is slowed down in the fire process, so that the material strength can be exerted to a greater extent, and the fire resistance is better;
(D) after the fire test is finished, closing the flame spray nozzle, then opening the exhaust system, entering a cooling stage, slowly cooling to 50 ℃ of the furnace temperature, detaching the load, keeping data acquisition all the time until the temperature is recovered to the room temperature, measuring the rebound deformation value of the test piece, re-measuring the deformation value of the test piece after the temperature is kept at the room temperature for one day, performing the post-fire residual bearing performance test on the fire-resistant composite floor subjected to the fire simulation fire-resistant performance test, and acquiring post-fire static load, mid-span maximum deformation and final residual deformation data to obtain the post-fire residual bearing capacity and the post-fire deformation recovery degree of the fire-resistant composite floor;
the contrast test shows that in the air exhaust and temperature reduction process, the cracks of the fire-resistant composite floor slab are closed, the interface slippage is small, the mid-span deformation recovery degree of the closed type composite floor slab is over 50 percent, the mid-span deformation recovery degree of the closed type composite floor slab is larger, the open type composite floor slab is brittle fracture when damaged, and the mid-span deformation cannot be recovered; in addition, the residual bearing capacity of the closed type composite floor slab after fire is also higher than 50 percent, so the closed type fire-resistant composite floor slab is proved to have good deformation restorability after fire, still has composite effect and integrity after fire, and has ductility and strength at high temperature superior to those of a necking and opening type composite floor slab and a composite floor slab adopting galvanized steel as a floor bearing plate;
(E) comparing the displacement and deformation recovery conditions between the profiled floor support plate 10 and the concrete 20 under the conditions of high temperature and room temperature after fire disaster, and carrying out shearing-bonding performance inspection at room temperature after fire disaster and cooling to compare the performance difference of the fire-resistant composite floor before and after fire disaster, and synthesizing new shearing-bonding coefficients m and k after fire disaster, and further concluding the fire-proof safety coefficient;
the significance of the m and k coefficients after fire lies in quantifying the shear-slip resistance of the interface between the profiled floor support plate 10 and the concrete 20 after fire, and the m and k coefficients are compared with those under normal use conditions to evaluate the strength of the combined effect and the attenuation degree of the shear-resistant bearing capacity of the two materials after the two materials are subjected to high temperature of fire, so as to provide theoretical support and scientific basis for further determining the fire safety coefficient.
In the steps of the method for testing the fire resistance of the fire-resistant composite floor slab, no tensile steel is placed on a test piece with normal temperature and fire-passing bonding coefficient, the structural bearing capacity formed by a plate section is taken as the most main detection element, the maximum value of the converted load of a substitute steel bar is found through general calculation, the load is applied during fire-passing, namely the maximum value of the converted load, the measurement of the bonding displacement data of a compression type floor bearing plate and concrete is added in a standard temperature rise detection method, the load is disassembled only when the temperature is slowly cooled to 50 ℃ of a furnace temperature after fire-passing, the test piece is placed at the room temperature for one day after the test piece measures the rebound deformation value, the deformation value of the re-measured test piece needs to be in the range of L/130, the standard bonding detection method is used for measurement, the pressure point is required to form 90 degrees.
Example two:
as shown in fig. 2 and 3, the refractory composite floor slab of the present embodiment is different from the first embodiment in that: in this embodiment, the fire-resistant composite floor slab further includes an anti-crack reinforcing mesh 8, the anti-crack reinforcing mesh 8 is formed by cross spot welding of steel bars for building structures, fire-resistant steel bars or fire-resistant weather-resistant steel bars, the anti-crack reinforcing mesh 8 is erected on a compression area of the concrete 20 above the profiled floor slab 10, and is integrated with the concrete 20 after the concrete 20 is poured, and the thickness of the concrete 20 above the anti-crack reinforcing mesh 8 is not less than 20mm, so as to protect the anti-crack reinforcing mesh 8 and ensure that the anti-crack reinforcing mesh is not fallen off and is not corroded due to contact with the outside.
In the third stage of the midspan deflection change trend of the floor slab in the standard temperature rise process under the actual fire condition, although the overall rigidity and strength of the floor are significantly reduced, eventually the anti-crack reinforcing mesh 8 and the profiled floor slab 10 together provide a "net-bag" effect without suddenly collapsing, for thin plates with smaller thickness such as 115mm and 125mm, the net bag effect is more obvious when the floor is damaged due to larger mid-span deflection limit value, the floor with the thickness not less than 150mm has less limit value of mid-span deflection, the net bag effect is not obvious, even if the damage condition is reached, the composite floor still has higher normal temperature bearing capacity and high temperature resilience capacity, so the anti-crack reinforcing mesh 8 strengthens the net bag effect, wherein the anti-crack reinforcing mesh 8 can provide tensile force to form a film effect, and the integral bearing capacity of the member under the condition of large deflection is increased.
The remaining features of this embodiment are the same as those of the first embodiment.
Example three:
as shown in fig. 4, the refractory composite floor slab of the present embodiment is different from the first embodiment in that: the profiled floor support plate 10 of this embodiment is a profiled floor support plate made of fire-resistant weather-resistant steel, the profiled floor support plate 10 is made of fire-resistant weather-resistant steel through integral roll forming, the cross section of the wedge-shaped portion of the profile rib 4 is regular hexagon, the overall shape of the buckling portion after the first buckling portion 2 and the second buckling portion 3 of the adjacent profiled floor support plate 10 are buckled and connected is also regular hexagon, the contact area between the profile rib 4 and the concrete 20 can be further increased, the combining ability of the profiled floor support plate 10 and the concrete 20 is enhanced, the profiled floor support plate 10 is protected by the concrete 20 and cannot fall off, the structural function of the profiled floor support plate is prevented from being lost, the stability of the composite floor structure is further enhanced, the service life of the fire-resistant composite floor is prolonged, and of course, the cross section of the wedge-shaped portion can also be other regular polygons, theoretically, the more the number of sides is, the larger the contact area between the profile rib 4 and the concrete 20 is, considering the processing and stress conditions, the more suitable the polygonal section of the wedge portion is generally a regular hexagon, a regular heptagon, a regular octagon or a regular nonagon, the longitudinal bottom plate reinforcing rib 5 is an arc, and in addition, no longitudinal reinforcing rib or concave-convex indentation is arranged on the vertical rib of the profile rib 4 in this embodiment.
The remaining features of this embodiment are the same as those of the first embodiment.
Example four:
as shown in fig. 5, the fire-resistant composite floor slab of the present embodiment is different from the third embodiment in that: in this embodiment, the cross section of the wedge-shaped portion of the profiled rib 4 is circular, and the first buckling portion 2 of the profiled floor support plate 10 adjacent to the second buckling portion 3 is also circular in the overall shape of the buckling portion after being buckled and connected, so that the contact area between the profiled rib 4 and the concrete 20 is increased, the stress uniformity is better, the combining ability of the profiled floor support plate 10 and the concrete 20 is enhanced, the profiled floor support plate 10 is protected by the concrete 20 and cannot fall off, the structural function is prevented from being lost, the stability of the composite floor structure is further enhanced, and the service life of the fire-resistant composite floor is prolonged.
The rest of the characteristics of the embodiment are the same as those of the third embodiment.
The plate type of the profiled floor deck 10 described in the above embodiments is for illustration only and is not intended to limit the scope of the present invention.
The fireproof composite floor slab has the advantages of convenience and quickness in construction, reduction in construction period, low cost, high bearing capacity, good ductility and the like. (1) Accelerating the construction progress: the profiled floor support plate 10 is used as a template for pouring the concrete 20, steps of formwork support, formwork removal and the like are omitted, so that time and labor are saved, the profiled floor support plate 10 can be used as a construction platform after being installed, and meanwhile, temporary support is not needed, and the work of the next construction plane is not influenced; the profiled floor support plate 10 replaces the reinforcing steel bars on the tension side of the floor slab, so that the workload of manufacturing and installing the reinforcing steel bars is saved, and the concrete tension cracking is not considered; (2) the composite floor slab has less concrete in a tension area, so that the self weight of the composite floor slab is reduced, the sizes of beams, columns and foundations can be correspondingly reduced, the permanent load of the whole structure is reduced, and the whole performance of the structure is improved; (3) the cavity part of the rib 4 can be used for placing various pipelines such as water and electricity, so that the structural layer and the pipelines are integrated, the floor height is indirectly increased or the building height is reduced, the size of the use space in the actual building can be increased, and the flexibility is brought to the building design; (4) in the construction stage, the profiled floor support plate 10 can be used as a continuous lateral support of a steel beam, so that the overall stable bearing capacity of the steel beam is improved, the lateral constraint condition of the steel beam is provided, and in the use stage, the overall stability of the steel beam and the local stability of an upper flange are improved; (5) compared with a traditional building structure system, the fireproof composite floor slab can greatly reduce labor cost and construction cost (no form removal, no temporary support and simultaneous construction of multiple layers), shorten the construction progress, achieve the effect of preventing slurry leakage without using a plug, and save the consumption of reinforcing steel bars and concrete; (6) the ceiling has the advantages of complete and attractive ceiling effect, capability of omitting an internal decoration ceiling, increasing space height, providing better sound insulation effect due to the fact that the bottom plate is closed, remarkably improving the safety performance and fire resistance of the building structure in China, reducing resource consumption and environmental pollution, reducing the life cycle cost of the building structure, and obtaining outstanding economic benefit, social benefit and ecological benefit.
The invention overcomes the defects and shortcomings of the prior art, the fire-resistant steel or fire-resistant weather-resistant steel profiled floor support plate is made of the substrate without a coating and a coating, and the gasification of the concrete and the coating bonding coating can not occur in a high-temperature state, so that the separation of the bonding interface between the concrete and the steel and the burst under high-temperature loading are avoided, and small cracks after slow cooling can be closed under the special effect of resilience; the invention adopts the profiled floor bearing plate made of fire-resistant steel or fire-resistant weather-resistant steel to form the combined floor slab by pouring and combining with concrete, fully utilizes the respective advantages and the cooperative working capacity of the fire-resistant steel or the fire-resistant weather-resistant steel and the concrete, generates the 'combined' effect, realizes the effect of 1+1 & gt 2, and is proved by tests to have the advantages of strong bearing capacity, good ductility, excellent fire resistance, easy damage repair, high efficiency, green environmental protection, flexible and variable forms, and the like, thereby being a novel high-performance combined floor slab which is suitable for various structural types and different key parts, and has stable deformation capacity and intact integral combined effect all the time after being tested, when bearing normal load, the fire-resistant combined floor slab is subjected to fire for about 60min to 950 ℃ according to a standard temperature rise curve, the floor slab deformation caused by the high-temperature action of fire is continuously and slowly developed, even if micro cracks visible to the naked eye occur, collapse still can not occur, after the fire-resistant steel composite floor slab is cooled to room temperature through air supply and air exhaust, the deformation recovery capability of the fire-resistant steel composite floor slab is extremely strong, the micro cracks are closed, the deformation recovery degree of a midspan part is higher than 50%, the residual bearing capacity after fire disaster is higher than 50%, the interface slippage is small, good combination effect and integrity are still achieved, the structural stability of a building is greatly improved, the fire hazard safety hazard of the building can be reduced to the maximum extent, the structural stability of the building can be guaranteed when and after the fire disaster occurs, secondary disasters are avoided, the safety and the service life of the building are guaranteed, through a simulated fire disaster test, the fire-resistant composite floor slab is not easy to generate cracks during fire disaster, collapse can not be caused, when the constant load temperature rises until the deformation of the fire-resistant composite floor slab reaches half of the limit deformation of damage, almost no crack appears, even if the constant load is heated until the deformation of the floor reaches the limit deformation of damage, the concrete part of the pulled area at the bottom has slight crack, the width and the depth of the crack are much smaller than those of the common floor, and even if the floor is burnt to damage, the width of the crack is reduced and recovered or even closed due to the deformation recovery of the floor, so the residual bearing performance and the safety degree after fire disaster are very high; tests prove that the hollow closed-end profiled section with the closed cavity adopted by the fire-resistant steel or fire-resistant weather-resistant steel profiled floor support plate has excellent heat insulation and temperature resistance, the safety level of the fire-resistant composite floor slab composite structure before, in the middle and later periods before fire can be greatly improved, and the high temperature resistance of the fire-resistant steel or fire-resistant weather-resistant steel can be compared with that of the existing galvanized plate or other steel composite floor slabs, so that the conclusion can be drawn: (1) in the initial stage of fire, the temperature rise deformation of the fire-resistant composite floor slab is delayed, and the deformation is greatly reduced, so that the early safe evacuation time of fire can be prolonged, (2) in the middle high-temperature stage of fire, the contrast deformation amplitude is greatly improved, the fire-resistant composite floor slab always has stable continuous deformation capability and intact integral composite effect before damage, even if micro cracks visible to the naked eye appear, the collapse can not occur, the safety level in the fire fighting and disaster relief process can be improved, (3) after fire, the bonding performance can be maintained between the concrete and the profiling floor support plate without loosing, the cracks of the fire-resistant composite floor slab are closed, the deformation recovery degree of the middle part is higher than 50%, the residual bearing capacity after fire is higher than 50%, the interface slippage is small, the composite effect and the integrity are still provided, so that the damage after recovery is small, the safety level after fire disaster can be improved, so that the structural safety performance of the building is greatly improved; therefore, the fire-resistant composite floor slab has the advantages of strong fire resistance, high safety, good deformation performance and strong cooperative working capability, is slow in deformation after a fire disaster occurs, is not easy to crack and collapse, is quick in deformation recovery, and is small in damage to a combined effect.
In addition, the method for testing the fire resistance of the fire-resistant composite floor slab is specially carried out aiming at a novel composite structure form of a profiled steel plate with a fire resistance function, the improvement of the fire resistance brought by the novel structure form is comprehensively tested and verified, the surface bonding verification of the concrete and the profiled floor support plate after fire passing is increased through a specific innovative detection method, the index of the structure maintaining effectiveness is obtained, the verification coefficient can be fed back to the original calculation formula to form a post-disaster structure safety calculation method, namely post-disaster structure evaluation, a path is provided for the deep system research of the fire resistance design method of the members, so that on the basis of the traditional composite structure system, the method is favorable for perfecting and optimizing the cooperative work mechanism of the high-performance composite floor slab, other horizontal members and vertical members, and a reasonable arrangement scheme of the novel structure system is provided, The stress mechanism, the fire-resistant failure mechanism and the performance design method are combined with the demonstration application of key building engineering, and a novel high-rise building combined structure system is further perfected.
The invention can be widely applied to the field of buildings.

Claims (10)

1. A fire-resistant composite floor slab is characterized in that: the fireproof composite floor slab comprises a fireproof steel or fireproof weather-resistant steel profiled floor bearing plate (10) and concrete (20), wherein the profiled floor bearing plate (10) comprises a profiled rib (4) with a closed hollow part, the profiled floor bearing plate (10) is made of a base material without a coating and a skin, the concrete (20) is poured on the profiled floor bearing plate (10), the upper surface of the concrete (20) after pouring is strickled off and maintained, and then the concrete and the profiled floor bearing plate (10) are combined into a whole to be used as a fireproof composite floor slab, when the fireproof composite floor slab bears normal load, the deformation of the fire at the initial stage is delayed, the deformation amplitude is reduced, the fire does not collapse at the high-temperature stage at the middle stage, the stable deformation capability and the integral composite effect are kept, the fire is recovered to the room temperature after the fire, and the bonding performance between the concrete (20) and the profiled floor bearing plate (10), the deformation recovery degree and the residual bearing capacity are both higher than 50%, and the combined effect and the integrity are still realized.
2. The fire resistant composite floor slab of claim 1, wherein: the fire-resistant composite floor slab further comprises an anti-cracking reinforcing mesh (8), the anti-cracking reinforcing mesh (8) is formed by adopting steel bars for building structures or fire-resistant steel bars or fire-resistant weather-resistant steel bars through cross spot welding, the anti-cracking reinforcing mesh (8) is erected on a compression area of the concrete (20) above the compression type floor bearing plate (10), and the concrete (20) and the anti-cracking reinforcing mesh are combined into a whole after the concrete (20) is poured.
3. The fire resistant composite floor slab of claim 2, wherein: the thickness of the concrete (20) above the anti-cracking reinforcing mesh (8) is not less than 20 mm.
4. The fire-resistant composite floor slab according to any one of claims 1 to 3, wherein: die mould building carrier plate (10) are made through integrative roll forming by fire-resistant steel or fire-resistant weathering steel, including bottom plate (1), be located respectively the bottom plate (1) is controlled first buckling parts (2) and second buckling parts (3), the interval at both ends and set up in a plurality of at bottom plate (1) middle part type rib (4), it is adjacent die mould building carrier plate (10) first buckling parts (2) with second buckling parts (3) looks adaptation lock is connected.
5. The fire resistant composite floor slab of claim 4, wherein: the profile rib (4) comprises a lower vertical rib and an upper closed hollow part.
6. The fire-resistant composite floor slab according to claim 1 or 5, wherein: the cross section of the closed hollow part is triangular or regular polygonal or circular.
7. The fire resistant composite floor slab of claim 4, wherein: and longitudinal or transverse bottom plate reinforcing ribs (5) protruding upwards are arranged on the bottom plate (1) at intervals.
8. The fire resistant composite floor slab of claim 4, wherein: and longitudinal reinforcing ribs (6) or concave-convex indentations are arranged on the profile ribs (4).
9. A fire resistance testing method of a fire resistant composite floor slab as claimed in any one of claims 1 to 8, characterized in that: the method comprises the following steps:
(A) respectively carrying out material mechanical property tests on the fire-resistant steel or fire-resistant weather-resistant steel adopted by the profiling floor bearing plate (10) and the concrete (20) adopted by the fire-resistant composite floor slab: the mechanical property indexes of the fire-resistant steel or the fire-resistant weathering steel at normal temperature and high temperature are measured by adopting a standard tensile test, a stress-strain constitutive model is obtained, and then the mechanical property indexes of the fire-resistant steel or the fire-resistant weathering steel, such as the elastic modulus, nominal yield strength, tensile strength, compressive strength, yield ratio, elongation after fracture and the like, are obtained, so that the fire-resistant steel or the fire-resistant weathering steel can meet various requirements of the fire-resistant steel or the fire-resistant weathering steel; measuring the standard cubic compressive strength of the concrete by adopting a standard test method so as to reflect the basic mechanical properties of the concrete of the same batch;
(B) pouring and maintaining the fire-resistant composite floor slab, carrying out a shearing-bonding performance test on the fire-resistant composite floor slab, so as to measure the shear bonding coefficient of the interface of the profiled floor support plate (10) and the concrete (20), obtain the longitudinal shear bearing capacity of the fire-resistant composite floor slab through regression, obtain the mechanical properties of the fire-resistant composite floor slab, such as the longitudinal shear bearing capacity, the longitudinal sliding characteristic, the flexural deformation characteristic, the compression failure mode and the like at normal temperature, and regression analysis is carried out to obtain empirical coefficients m and k, a calculation formula of the longitudinal shearing bearing capacity of the fire-resistant composite floor slab and a related curve, according to the mechanical property index, the crack development condition and the deformation characteristics of the upper surface, the lower surface and the internal key parts of the fireproof composite floor slab, the cooperative working mechanism between the profiling floor bearing plate (10) and the concrete (20) is researched, and the cooperative working mechanism is used for comparing the difference of the stress properties of the composite floor slab under the actions of normal temperature and high temperature;
(C) pouring the fire-resistant composite floor slab and maintaining, and carrying out fire simulation fire resistance performance test on the fire-resistant composite floor slab to simulate and obtain the fire resistance performance of the fire-resistant composite floor slab when an actual fire disaster occurs: judging the failure and damage control conditions of the refractory composite floor through a standard temperature rise process and a standard temperature rise curve in the furnace, acquiring the bonding displacement data, the refractory limit, the damage form, the mid-span deflection, the end sliding, the crack distribution, the stress strain distribution, the temperature change of the interface of the profiled floor bearing plate (10) and the concrete (20), the average temperature rise and the maximum temperature rise of the fire-receiving surface and the back fire surface, the temperature distribution rule of the fire-receiving surface, the back fire surface and the internal key parts and the temperature change rule of the concrete along the plate thickness direction, combining the test result with the finite element result and parametric analysis, and judging and determining the main influence factors influencing the fire resistance performance of the refractory composite floor;
(D) after the fire test is finished, closing the flame spray nozzle, then opening the exhaust system, entering a cooling stage, slowly cooling to 50 ℃ of the furnace temperature, detaching the load, keeping data acquisition all the time until the temperature is recovered to the room temperature, measuring the rebound deformation value of the test piece, re-measuring the deformation value of the test piece after the temperature is kept at the room temperature for one day, performing the post-fire residual bearing performance test on the fire-resistant composite floor subjected to the fire simulation fire-resistant performance test, and acquiring post-fire static load, mid-span maximum deformation and final residual deformation data to obtain the post-fire residual bearing capacity and the post-fire deformation recovery degree of the fire-resistant composite floor;
(E) and comparing the displacement and deformation recovery conditions between the profiled floor bearing plate (10) and the concrete (20) under the conditions of high temperature and room temperature after cooling in fire, and carrying out shearing-bonding performance inspection at room temperature after cooling in fire so as to compare the performance difference of the fire-resistant composite floor before and after fire, synthesize new shearing-bonding coefficients m and k after fire, and further conclude the fire safety coefficient.
10. The method for testing the fire resistance of a fire-resistant composite floor slab according to claim 9, wherein: in the step (C), high-temperature-resistant thermocouples (9) are embedded in the concrete (20) at the midspan part of the fire-resistant composite floor slab and the interface between the profiled floor bearing plate (10) and the concrete (20) and close to the top surface and the bottom surface of the profiled floor bearing plate (10) so as to measure the temperature development conditions of all parts; arranging a plurality of thermocouples (9) on the back fire surface of the fire-resistant composite floor slab to obtain the heat insulation performance index of the fire-resistant composite floor slab test piece; the thermocouples (9) are symmetrically and uniformly arranged on the inner wall of the horizontal combustion furnace along the length direction of the furnace and are used for monitoring the temperature distribution and difference of different positions in the furnace, and the temperature rise of each part is strictly controlled within a specified range by adjusting the switch of a flame nozzle and the air supply frequency in time so as to simulate the indoor fire condition of a uniform temperature field; a pre-buried wire is led out from each thermocouple (9); in the temperature rising process, measuring the instantaneous temperature of the key suspicious part on the back fire surface of the refractory combined floor slab test piece by using a handheld infrared temperature detector at fixed time intervals; arranging a displacement sensor at the central point of the back fire surface of the test piece of the profiling floor bearing plate (10) to determine the midspan deflection change process; and the displacement sensors are additionally arranged at the left-right symmetrical positions of the back fire surface of the test piece of the profiling floor bearing plate (10) so as to determine and verify whether the fire-resistant composite floor slab generates integral symmetrical bending deformation in the fire receiving process.
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