CN111980418A - Construction method for hoisting steel structure roof of beam string dome in large-scale public building engineering - Google Patents

Construction method for hoisting steel structure roof of beam string dome in large-scale public building engineering Download PDF

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Publication number
CN111980418A
CN111980418A CN202010866482.4A CN202010866482A CN111980418A CN 111980418 A CN111980418 A CN 111980418A CN 202010866482 A CN202010866482 A CN 202010866482A CN 111980418 A CN111980418 A CN 111980418A
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China
Prior art keywords
beam string
sliding
string
hoisting
tensioning
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Inventor
成军
成张佳宁
徐晶晶
李伟杰
黄坤坤
葛晓晗
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Nantong University
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Nantong University
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Priority to CN202010866482.4A priority Critical patent/CN111980418A/en
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    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04GSCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G21/00Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
    • E04G21/14Conveying or assembling building elements
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04GSCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G21/00Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
    • E04G21/12Mounting of reinforcing inserts; Prestressing
    • E04G21/121Construction of stressing jacks
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00Measuring or testing not otherwise provided for
    • G01D21/02Measuring two or more variables by means not covered by a single other subclass

Abstract

The invention discloses a construction method for hoisting a steel structure roof of a beam dome in a large-scale public building engineering.

Description

Construction method for hoisting steel structure roof of beam string dome in large-scale public building engineering
Technical Field
The invention belongs to the field of building construction, and particularly relates to a construction method for hoisting a steel structure roof of a beam string dome in large-scale public building engineering.
Background
At present, a plurality of large-span buildings such as stadiums, exhibition halls and the like are built in various places. These buildings tend to be local landmark buildings. Large-span building roofing systems often employ beam-string systems. The string beam system is characterized in that a prestress high-strength steel cable is introduced. The strength of the steel cable body can reach 1670 MPa. The introduction of high-strength materials means that the cross section of the member is smaller, and a lighter building effect is achieved. The steel cable is prestressed, so that on one hand, an inverted arch can be provided for the structure, and the problem of overlarge deflection of a large-span structure is effectively solved; on the other hand, the stress distribution of the structure can be improved, and the structure cost is reduced. Therefore, the beam-string dome steel structure roof system is a promising novel structure system.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the defects of the prior art, the invention provides a construction method for hoisting a steel structure roof of a beam string dome in large-scale public building engineering.
The technical scheme is as follows: a construction method for hoisting a steel structure roof of a beam-string dome in large-scale public building engineering specifically comprises the following operations:
(1) field assembly of beam string
The upper chord of a single beam needs to be assembled on site after being processed in a factory in a segmented manner, the assembly of the beam is carried out by adopting an assembly jig frame erected on the ground as much as possible, and the assembly is sequentially pushed; after the assembly is finished, the first tensioning of the beam string is finished on the ground assembly jig;
(2) beam string hoist
Hoisting all beam strings by adopting a double-machine hoisting crane to install the beam strings into a sliding unit; generally, a double machine or a triple machine is adopted to lift and hang to a sliding position, and then stay bars and purlins between beam string structures are installed to form a rigid frame;
(3) beam string slipping
After a beam string slipping unit is hoisted, the whole slipping must be started in time so as to organize the hoisting of the next group of slipping units; adopting a construction method of sectional sliding, and arranging a slideway by utilizing a concrete frame beam;
(4) tensioning of beam string
The prestress tensioning is completed in two times, the first time is tensioned to 30% of the designed tensioning force on the ground, the stability of a single truss in the hoisting process is ensured, and the second time is symmetrically tensioned to the designed tensioning force in batches; aiming at the structural form of each project and the characteristics of a steel cable system, a special tensioning tool is designed, a hydraulic oil pump, a calibration jack, an oil pipeline, an operation program and the like need to be tested and detected in advance, and the test can be applied to cable tensioning projects through the rear part.
As an optimization: hoisting the beam string: assembling the beam string, lifting and hanging the beam string by using a truck crane after the first tensioning is finished, directly placing the lifted and hung beam string on a sliding track of the top of the concrete beam, arranging wind-holding ropes at different positions of the beam string in advance, and immediately fixing the beam string after the beam string is in place;
after the first beam string beams are fixed, hoisting, positioning and reinforcing the second beam string beams, and connecting the support systems among the beam string beams in time. When the two beam strings, the middle support system, the purlines and the like are completely connected and installed, and no potential safety hazard exists in each detail link, the beam string unit group can be moved forwards in a sliding manner to a designed position, and then the next beam string is hoisted in place.
As an optimization: in the string beam slides, the slide way is arranged: the slide way plays a role in bearing, guiding and transversely limiting the horizontal displacement of the slide plate in the whole horizontal traction, is arranged along the axis, and is higher than a concrete column beam due to the foundation embedded anchor bolt, a steel beam needs to be erected for leveling firstly, a certain distance is considered to be left between the slide block and the slide way, so that the slide block is prevented from being blocked in the slide way, and a 25mm gap is left between each side of the slide block and the slide way when the slide block is manufactured; in addition, the contact surface of the sliding block and the sliding groove is ground into a circular arc shape during processing, so that the contact area between the sliding block and the sliding groove is reduced to reduce the sliding friction resistance.
As an optimization: in the sliding of the beam string, the sliding of the beam string is as follows: after the first beam string beam and the second beam string beam are connected into a whole, the first beam string beam and the second beam string beam slide to a designed position through two preset slide ways and two groups of synchronous traction equipment; hoisting a third beam and a fourth beam, connecting a support system and a purline between the two beams, and sliding to a designed position to be in place, circulating until the plurality of beams are assembled into a whole, directly hoisting the rest beams in place, and making a scale on a slide way to ensure the synchronism of sliding in order to ensure the synchronism of sliding at two ends; the specific operation steps are as follows:
the method comprises the following steps: connecting the supporting systems in the middle of the first beam and the second beam;
step two: sliding one sliding unit to a designed position, and assembling a second sliding unit (a third beam and a fourth beam);
step three to step five: sequentially sliding the second sliding unit to the fourth sliding unit to a designed position, and connecting and fixing the support systems between the adjacent units;
step six: and finally, directly hoisting the two beam string beams in place, and connecting and fixing the support systems between the adjacent units after the beam string beams are in place.
As an optimization: in the sliding process of the beam string, jacking and positioning: after each sliding unit slides to a designed position, after the sizes of all the parts meet the design requirements, the steel support is used as a fulcrum outside each beam string, a Q16T jack is adopted to jack up the whole sliding unit, then a sliding block device, a sliding groove and a sliding H steel beam below the sliding unit are dismantled, and then the upper structure is lowered to a designed elevation to be in place.
As an optimization: in order to ensure the safety in the tensioning process, the whole tensioning process is monitored and controlled, and the main control measures comprise the following three aspects: controlling the tension and elongation values of the steel cable, controlling the stress of the steel structure and controlling the deformation of the structure;
the control of the tension force of the steel cable is mainly controlled, the control of the elongation value of the steel cable is assisted, the tension force of the steel cable is reflected through the data of the oil pressure sensor, and after the actual tension is finished, the tension force and the elongation value of the steel cable are within 5 percent of the theoretically calculated tension force and elongation value, so that the requirements of relevant specifications are met;
monitoring the stress and the structural deformation of the steel structure as an auxiliary monitoring means in the engineering tensioning process, selecting a rod piece with larger stress of the steel structure, monitoring the stress change by using a vibrating wire strain gauge, selecting a point in the middle of each truss string, monitoring and controlling the deformation, and monitoring the vertical deformation of the steel structure by using a level gauge.
As an optimization: the prestressed construction monitoring should run through the whole construction process, and the monitoring content of each construction stage is as follows:
firstly, before each tensioning, whether a test instrument works normally or not is checked, and an initial reading is read;
secondly, in the tensioning process of each batch, test instruments such as a dial indicator, a total station, a reflector, a vibrating wire strain gauge and the like cannot be moved, once the test instruments move, tensioning must be stopped, the test instruments are readjusted, tensioning can be carried out after the initial reading is read again, and the situation is recorded;
thirdly, after one batch is stretched, reading data in time, analyzing, comparing the data with a theoretical value, and continuously stretching the next batch after the structural condition is determined to be normal; if the problem exists, the problem is solved with related personnel in time;
fourthly, the testers need to be fixed, namely, dedicated personnel need to carry out testing work.
Has the advantages that: the dome roof with the plurality of string beams has the advantages of simple structure, definite force transfer, convenient and quick construction, perfect combination of building modeling and structural arrangement and the like, and has wide application prospect in the aspect of large-span space structures.
Drawings
FIG. 1 is a schematic plan view of a sports natatorium of the present invention;
FIG. 2 is a schematic view of a beam string of the present invention;
FIG. 3 is a schematic process flow diagram of the present invention;
FIG. 4 is a schematic view of a beam string assembly jig of the present invention;
fig. 5 is a schematic diagram of the setting of the beam string sliding chute.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below so that those skilled in the art can better understand the advantages and features of the present invention, and thus the scope of the present invention will be more clearly defined. The embodiments described herein are only a few embodiments of the present invention, rather than all embodiments, and all other embodiments that can be derived by one of ordinary skill in the art without inventive faculty based on the embodiments described herein are intended to fall within the scope of the present invention.
Examples
The roof of the sports stadium in a certain sports center is crescent, the plane size is about 180mx130m, and the highest point elevation of the roof structure is 23 m. The roof steel structure adopts orthogonal primary and secondary beams, wherein the large-span steel roof beam adopts a beam string structure, and the maximum span is 58 m. The main body is a reinforced concrete frame, and the roof is a steel structure single-layer latticed shell structure.
The invention is mainly characterized in that the large-span beam string structure in a sports swimming pool is shown in figure 1, the main section of the beam string is Box800x300x25x30, a high vanadium rope is designed below the beam string structure to perform reverse jacking force on the beam string structure, the total length of the large-span beam string above the sports pool is 56m at most, the weight of a whole beam is 28.2t, the hoisting height is 21.3m at most, the total length of the large-span beam string above the sports pool is 42m at most, the weight of the whole beam is 24t, and the hoisting height is 19.3m at most. The beam string has the difficulties of long length, heavy weight and the like, and has extremely high requirements on the aspects of member segmentation, transportation, field splicing, hoisting, precision and the like.
1. Technical characteristics
The prestressed stay cable is used as a flexible material with tensile strength far higher than that of concrete and steel, has remarkable superiority in a roof structure of a large-span venue, is combined with a pressed and bent member of a steel structure, and can exert respective strength from the angle of material strength, so that the self weight of the large-span structure is smaller, the building aesthetic feeling of conciseness, lightness and various changes can be realized conditionally, and the aesthetic tendency of modern buildings is met.
(1) High bearing capacity
The prestress applied in the cable in the beam string structure can control the bending moment of the rigid member and the distribution. For example, when the rigid member is a beam, a brace rod is arranged in the beam span, the lower end of the brace rod and two ends of the beam are both connected with a cable, and the beam is simply subjected to internal bending moment under the action of uniformly distributed loads; after the prestressing has been applied in the cable, the cable forces will cause a negative bending moment in the beam via the support and the stay.
(2) Little structural deformation under the action of using load
After the rigid member and the cable in the beam string structure form the integral rigidity, the rigidity of the space stress structure is far greater than that of a pure rigid member, and the deformation of the beam string structure is much smaller than that of the pure rigid member under the same use load. (3) Self-balancing function
When the rigid member is an arch, a large horizontal thrust will be generated at the abutment. The introduction of the cable can balance the lateral force, thereby reducing the requirement on the lateral resistance of the lower structure, ensuring the stress of the support to be definite and being easy to design and manufacture.
(4) Strong structural stability
The beam string structure ensures that the tensile property of the cable is fully exerted, and simultaneously, the rigidity and the shape stability of the system are greatly enhanced due to the introduction of the rigid member with the compression resistance and the bending resistance. Meanwhile, if the relative positions of the cables, the stay bars and the rigid members are properly adjusted, the integral stability of the beam string structure can be ensured.
(5) Strong adaptability of building moulding
The appearance of the rigid member in the beam string structure can be freely selected according to the building function and the aesthetic requirement, and the stress characteristic of the structure cannot be influenced. For example, the upper chord of the Pudong international airport roof is a cross section formed by welding steel pipes, and the structural appearance of the Pudong international airport roof is like spread in the flying mode of flapping; the roof upper chord of Guangzhou International convention and exhibition center is a space truss, and the structure appearance is like a swimming fish. The building shape and the structural arrangement of the beam string structure can be perfectly combined, so that the beam string structure is suitable for large-span space structures with various functions.
(6) Convenient for manufacturing, transporting and constructing
Compared with spatial structures such as latticed shells and net racks, the types and the number of the members and the nodes of the beam string structure are greatly reduced, and the structure is greatly convenient to manufacture, transport and construct. In addition, partial construction errors can be eliminated by controlling the tension of the steel cable, and the construction quality is improved.
2. Principle of the process
The stress mechanism of the beam string structure is that the upper string bending member generates reverse deflection by applying prestress in the lower string stay cable, the final deflection of the structure under the load action is reduced, and the stay bar provides elastic support for the upper string bending member, so that the stress performance of the structure is improved. The common compression bending component of the upper chord adopts an arched beam or a truss arch, and the horizontal thrust of the arch under the action of load is borne by the tensile component of the lower chord, so that the load of the arch on the support is reduced, and the horizontal displacement of the sliding support is reduced. Therefore, as shown in fig. 2, the beam string structure can fully exert the strong tensile property of the high-strength cable to improve the stress performance of the whole structure, so that the bending member and the tensile member take the advantages and make up for the disadvantages to cooperatively work, thereby achieving self-balance and fully exerting the function of each structural material.
The beam string structure fully exerts the tension performance of the cable, and simultaneously, the rigidity and the stability of the system are greatly enhanced due to the truss or the arch with the compression resistance and the bending resistance. And because the beam string structure is a self-balancing system, the stress of the supporting structure is greatly reduced. It is possible to minimize the force of the beam string structure on the support structure if the pretensioning force and the graded loading are applied properly graded during the construction process.
3. Construction process flow and operation key points
The process flow diagram of the invention is shown in fig. 3, and the specific operations are as follows:
1 construction difficulties and measures
(1) Field assembly of beam string
The upper chord of the single beam needs to be assembled on site after being processed in a factory in a sectional way. Assembling beam strings by erecting an assembling jig frame on the ground as much as possible, and sequentially advancing the assembling; and finishing the first tensioning of the beam string on the ground assembly jig frame after the assembly is finished.
(2) Beam string hoist
Due to construction reasons of fields, civil engineering and the like, all beam string hoisting is installed into a sliding unit by adopting a double-machine hoisting crane. Generally, a double machine or a triple machine is adopted to lift and hang to a sliding position, and then support rods and purlins between beam string structures are installed to form a rigid frame.
(3) Beam string slipping
After a beam string slipping unit is hoisted, the whole slipping unit must start to slip in time so as to organize the hoisting of the next group of slipping units. The construction method of segmental slippage is adopted, and the slideway is arranged by utilizing a concrete frame beam.
(4) Tensioning of beam string
The prestress tensioning is completed in two times, the first time is tensioned to 30% of the designed tensioning force on the ground, the stability of a single truss in the hoisting process is ensured, and the second time is symmetrically tensioned to the designed tensioning force in batches.
Aiming at the structural form of each project and the characteristics of a steel cable system, a special tensioning tool is designed, a hydraulic oil pump, a calibration jack, an oil pipeline, an operation program and the like need to be tested and detected in advance, and the test can be applied to cable tensioning projects through the rear part.
2-string beam on-site assembling scheme
The design and the arrangement of the assembly jig frame are determined according to the segmentation condition of the upper chord arch frame of the beam string and the position of the segmentation point, and meanwhile, the tension chord member needs to be avoided. In order to ensure the assembly precision of the beam string and enable the tensioning to be unaffected, and simultaneously considering the influence of horizontal movement of the main truss in the tensioning process of the jig frame, factors of facilitating ground installation of the tensioning cable, facilitating lifting of the beam string after tensioning and the like, the pipe bracket capable of adjusting the height and the flatness is placed at the upper end of the cross beam of the steel frame.
As shown in fig. 4, when assembling the jig frame, a gap is arranged on the broken surface to leave a welding space. When welding under the interface, the welder can do this on a temporary platform. In order to ensure that the radian of the original state of the beam string is consistent with the design, the elevation measurement control of the moulding bed fulcrum needs to meet the requirement of the designed elevation. Before the positioning, firstly, the jig frame is padded according to the elevation and the axis of the segmentation point of the beam string to enable the elevation to basically reach the designed position, and fine adjustment is carried out after the positioning.
In place, attention is paid to the control of the gap and elevation of the interface and the position of the segmentation point is substantially in the center of the jig frame. And welding after the adjustment and correction are finished, wherein the welding interface needs to be polished for smooth transition.
3 construction of steel castings
According to design requirements, because the related nodes of the steel structure and the steel cable bear large cable force influence during tensioning, the steel structure of the nodes adopts steel casting nodes so as to ensure that structural deformation and stress in the tensioning process and after tensioning are within the design requirements.
The large beam string steel structure roofing steel castings are more in quantity, the molding is complicated and changeable, the appearance of the same model is similar and different, the shape design and the maintenance are carried out in the pouring process, and the checking and acceptance difficulty of the finished curved surface is large. The steel casting is a key node for connecting the steel structure and the steel cable under stress, ensures the internal quality and the appearance size and is the key for construction implementation.
4-piece string beam hoisting
And after the beam string assembly is completed and the first tensioning is completed, lifting and hanging are carried out by using a truck crane, and the beam string assembly is directly placed on a sliding track of the top of the concrete beam after being lifted and hung. Because the beam string is too long, before no space structure unit is formed, the stability of a single beam string is required to be ensured: the wind-holding ropes are arranged at different positions of the beam string in advance, and the beam string is fixed immediately after the beam string is in place.
After the first beam string beams are fixed, hoisting, positioning and reinforcing the second beam string beams, and connecting the support systems among the beam string beams in time. When the two beam strings, the middle support system, the purlines and the like are completely connected and installed, and no potential safety hazard exists in each detail link, the beam string unit group can be moved forwards in a sliding manner to a designed position, and then the next beam string is hoisted in place.
5-beam string slippage
(1) Slideway arrangement
The slide way plays the effect of bearing, direction and horizontal restriction slide horizontal displacement in whole horizontal traction, and the slide way is arranged along the axis. Because the foundation embedded anchor bolt is higher than the concrete column beam, a steel beam needs to be erected firstly for leveling. Considering that a certain distance should be left between the sliding block and the sliding groove, the sliding block is prevented from being blocked in the sliding groove, and a 25mm gap is left between the sliding block and the sliding groove when the sliding block is manufactured. In addition, the contact surface between the sliding block and the sliding groove is ground into a circular arc shape during processing, so that the contact area between the sliding block and the sliding groove is reduced to reduce the sliding friction resistance, and the specific structure is shown in fig. 5.
(2) Sliding of beam string
After the first beam string beam and the second beam string beam are connected into a whole, the first beam string beam and the second beam string beam slide to a designed position through two preset slide ways and two groups of synchronous traction equipment; and hoisting the third beam and the fourth beam, connecting a support system and a purline between the two beams, sliding to a designed position, and taking place, so that the operation is circulated until the plurality of beams are spliced into a whole, and the rest beams can be directly hoisted in place. In order to ensure the synchronous sliding of the two ends, a scale can be made on the slideway to ensure the synchronism of the sliding. The specific operation steps are as follows:
the method comprises the following steps: connecting the supporting systems in the middle of the first beam and the second beam;
step two: sliding one sliding unit to a designed position, and assembling a second sliding unit (a third beam and a fourth beam);
step three to step five: sequentially sliding the second sliding unit to the fourth sliding unit to a designed position, and connecting and fixing the support systems between the adjacent units;
step six: and finally, directly hoisting the two beam string beams in place, and connecting and fixing the support systems between the adjacent units after the beam string beams are in place.
(3) Jacking into position
After each sliding unit slides to a designed position, after the sizes of all the parts meet the design requirements, the steel support is used as a fulcrum outside each beam string, a Q16T jack is adopted to jack up the whole sliding unit, then a sliding block device, a sliding groove and a sliding H steel beam below the sliding unit are dismantled, and then the upper structure is lowered to a designed elevation to be in place.
6 prestressed construction
(1) Construction simulation calculation
And large finite element calculation software ANSYS and Xsteel are used as calculation tools to perform simulation calculation on the structure tensioning process.
The steel beams and nodes are created between the steel columns after the steel columns are created, a large number of steel structure common nodes are arranged in an Xsteel node library, the nodes can be parameterized by software, member nodes can be quickly and accurately established, and deepening time can be greatly shortened. When the node type does not exist in the node library, and a large number of nodes of the type exist in the project, artificial intelligence parameterized nodes can be created in software to meet design requirements.
(2) Prestress tension scheme
After the assembly of each beam on the ground is finished, performing first tensioning, hoisting and single-beam sliding; the whole structure slides in place, secondary tensioning is carried out after the purlines are installed, and symmetric batch tensioning is adopted in the tensioning process.
Steel cable approach
When the steel cable enters the field, large-scale machinery is used for unloading and hoisting. The entrance sequence and the unloading position of the cable are uniformly organized according to the order number, and the cable cannot be confused. The steel cable unloading vehicle is unloaded to the position close to the installation position as much as possible, and secondary guiding and transportation on site are avoided.
② steel cable spreading rope
According to the size and the diameter of the steel cable, a professional cable releasing disc is designed to release the cable so as to fully release the twisting force generated when the cable is wound. The cable is higher in installation height, and because the roof supports more, it is less to put the cable area, according to the condition of job site, prepares to adopt tower crane and hoist engine cooperation to carry out exhibition cable and shop.
And measuring the adjusting end of the steel cable.
The length of the wire rope is checked according to the designed length, and the adjusting end of the wire rope is adjusted.
Fourthly, actually measured data
The distance between the steel cable ear plates is checked and measured, the ear plates which do not meet the requirements are adjusted, and the accuracy of the steel cable after the installation is ensured.
Installing steel cable and cable clamp
And pulling the steel cable clamp close to the steel structure lug plate by using a winch, a chain block and the like to prepare tensioning.
Tension tool for field installation
Erecting operation scaffolds, installing tools and oil pumps on site, arranging steel strands, oil pipes, hydraulic equipment and the like, and preparing for starting tensioning construction.
7 selection of prestressed apparatus
The tensioning equipment adopts a special jack of a prestressed steel structure and a matched oil pump, an oil pressure sensor and a reading instrument. And calibrating the oil pressure sensor and the reading instrument according to the actual tension force required by the design and the prestress process.
During tensioning, a double-control principle is adopted: the cable force is mainly controlled, the elongation value is controlled as the auxiliary, and meanwhile, the structural deformation is considered. And immediately measuring and correcting after the prestressed steel cable is tensioned. If an abnormality is found, tensioning is suspended, the cause is found out, and after measures are taken, tensioning is continued.
8 stretch monitoring
In order to ensure the safety in the tensioning process, the whole tensioning process is monitored and controlled. The main control measures have the following three aspects: controlling the tension and elongation values of the steel cable, controlling the stress of the steel structure and controlling the deformation of the structure.
The control of the tension of the wire rope is mainly controlled, and the control of the elongation value of the wire rope is assisted. The tension of the steel cable is reflected by the data of the oil pressure sensor. After the actual tensioning is finished, the tension force and the elongation value of the steel cable are within 5% of the theoretically calculated tension force and elongation value, and the requirements of relevant specifications are met.
And monitoring the stress and the structural deformation of the steel structure as an auxiliary monitoring means for the tensioning process of the project. And selecting a rod piece with larger steel structure stress, monitoring stress change by using a vibrating wire strain gauge, selecting a point in the middle of each truss string, carrying out deformation monitoring control, and monitoring the vertical deformation of the steel structure by using a level gauge. The actual monitoring result is well matched with theoretical calculation data.
The prestressed construction monitoring should be throughout the entire construction process. The monitoring content of each construction stage is as follows:
firstly, before each tensioning, whether the testing instrument works normally or not is checked, and an initial reading is read.
Secondly, in each batch of tensioning process, test instruments such as a dial indicator, a total station, a reflector, a vibrating wire strain gauge and the like cannot be moved. Once moved, the tensioning must be stopped, the test instrument readjusted, tensioned after reading the initial reading again, and the situation recorded.
And thirdly, after one batch is stretched, reading data in time, analyzing, comparing with a theoretical value, and continuously stretching the next batch after the structural condition is determined to be normal. If there is any problem, the problem should be solved by the relevant personnel in time.
Fourthly, the testers need to be fixed, namely, dedicated personnel need to carry out testing work.
The tension acceptance standard of the finished product guy cable is as follows: ensuring the verticality of the stay bar, and ensuring that d/h is 1/200 as much as possible; the error of the inhaul cable is controlled within 15 percent; the error of the structure displacement is controlled within 20 percent.
The dome roof with the plurality of string beams has the advantages of simple structure, clear force transfer, convenient and quick construction, perfect combination of building modeling and structural arrangement and the like, and has wide application prospect in the aspect of large-span space structures.
With the continuous development of economy and the continuous improvement of the scientific and technical level, the beam string structure becomes more and more mature. The prestress degree of the beam string structure is higher and higher. With the increase of the prestress level, the steel consumption of the structure is lower and lower, and the efficiency of the structure is higher and higher.
With the development of beam string structure, the construction method and the guarantee measure of prestress forming in the construction process are not problematic in engineering practice. In the future, the connection mode of the lower chord cable and the web member in the beam string structure is improved, the cable head structure and the connection mode of the web member and the upper chord member are improved continuously, the integrity of the beam string structure is enhanced more and more, and the structural form is novel more and more. Meanwhile, along with the research, the stress of the beam string structure is more reasonable, the profit loss of each item is not caused, and the bearing capacity is higher. Advanced construction equipment and construction technology can also lead the construction speed of the beam string structure to be faster and faster, and the construction period to be shorter and shorter. The rapid development of building materials can also push the beam string structure to move towards the economic green direction. The future beam string structure is not only limited to the building industry, but also permeates various industries.

Claims (7)

1. A construction method for hoisting a steel structure roof of a beam string dome in large-scale public building engineering is characterized by comprising the following steps: the specific operation is as follows:
(1) field assembly of beam string
The upper chord of a single beam needs to be assembled on site after being processed in a factory in a segmented manner, the assembly of the beam is carried out by adopting an assembly jig frame erected on the ground as much as possible, and the assembly is sequentially pushed; after the assembly is finished, the first tensioning of the beam string is finished on the ground assembly jig;
(2) beam string hoist
Hoisting all beam strings by adopting a double-machine hoisting crane to install the beam strings into a sliding unit; generally, a double machine or a triple machine is adopted to lift and hang to a sliding position, and then stay bars and purlins between beam string structures are installed to form a rigid frame;
(3) beam string slipping
After a beam string slipping unit is hoisted, the whole slipping must be started in time so as to organize the hoisting of the next group of slipping units; adopting a construction method of sectional sliding, and arranging a slideway by utilizing a concrete frame beam;
(4) tensioning of beam string
The prestress tensioning is completed in two times, the first time is tensioned to 30% of the designed tensioning force on the ground, the stability of a single truss in the hoisting process is ensured, and the second time is symmetrically tensioned to the designed tensioning force in batches; aiming at the structural form of each project and the characteristics of a steel cable system, a special tensioning tool is designed, a hydraulic oil pump, a calibration jack, an oil pipeline, an operation program and the like need to be tested and detected in advance, and the test can be applied to cable tensioning projects through the rear part.
2. The construction method for hoisting the steel structure roof of the beam string dome in the large-scale public building engineering according to claim 1, characterized in that: hoisting the beam string: assembling the beam string, lifting and hanging the beam string by using a truck crane after the first tensioning is finished, directly placing the lifted and hung beam string on a sliding track of the top of the concrete beam, arranging wind-holding ropes at different positions of the beam string in advance, and immediately fixing the beam string after the beam string is in place;
after the first beam string beams are fixed, hoisting, positioning and reinforcing the second beam string beams, and connecting the support systems among the beam string beams in time. When the two beam strings, the middle support system, the purlines and the like are completely connected and installed, and no potential safety hazard exists in each detail link, the beam string unit group can be moved forwards in a sliding manner to a designed position, and then the next beam string is hoisted in place.
3. The construction method for hoisting the steel structure roof of the beam string dome in the large-scale public building engineering according to claim 1, characterized in that: in the string beam slides, the slide way is arranged: the slide way plays a role in bearing, guiding and transversely limiting the horizontal displacement of the slide plate in the whole horizontal traction, is arranged along the axis, and is higher than a concrete column beam due to the foundation embedded anchor bolt, a steel beam needs to be erected for leveling firstly, a certain distance is considered to be left between the slide block and the slide way, so that the slide block is prevented from being blocked in the slide way, and a 25mm gap is left between each side of the slide block and the slide way when the slide block is manufactured; in addition, the contact surface of the sliding block and the sliding groove is ground into a circular arc shape during processing, so that the contact area between the sliding block and the sliding groove is reduced to reduce the sliding friction resistance.
4. The construction method for hoisting the steel structure roof of the beam string dome in the large-scale public building engineering according to claim 1, characterized in that: in the sliding of the beam string, the sliding of the beam string is as follows: after the first beam string beam and the second beam string beam are connected into a whole, the first beam string beam and the second beam string beam slide to a designed position through two preset slide ways and two groups of synchronous traction equipment; hoisting a third beam and a fourth beam, connecting a support system and a purline between the two beams, and sliding to a designed position to be in place, circulating until the plurality of beams are assembled into a whole, directly hoisting the rest beams in place, and making a scale on a slide way to ensure the synchronism of sliding in order to ensure the synchronism of sliding at two ends; the specific operation steps are as follows:
the method comprises the following steps: connecting the supporting systems in the middle of the first beam and the second beam;
step two: sliding one sliding unit to a designed position, and assembling a second sliding unit (a third beam and a fourth beam);
step three to step five: sequentially sliding the second sliding unit to the fourth sliding unit to a designed position, and connecting and fixing the support systems between the adjacent units;
step six: and finally, directly hoisting the two beam string beams in place, and connecting and fixing the support systems between the adjacent units after the beam string beams are in place.
5. The construction method for hoisting the steel structure roof of the beam string dome in the large-scale public building engineering according to claim 1, characterized in that: in the sliding process of the beam string, jacking and positioning: after each sliding unit slides to a designed position, after the sizes of all the parts meet the design requirements, the steel support is used as a fulcrum outside each beam string, a Q16T jack is adopted to jack up the whole sliding unit, then a sliding block device, a sliding groove and a sliding H steel beam below the sliding unit are dismantled, and then the upper structure is lowered to a designed elevation to be in place.
6. The construction method for hoisting the steel structure roof of the beam string dome in the large-scale public building engineering according to claim 1, characterized in that: in order to ensure the safety in the tensioning process, the whole tensioning process is monitored and controlled, and the main control measures comprise the following three aspects: controlling the tension and elongation values of the steel cable, controlling the stress of the steel structure and controlling the deformation of the structure;
the control of the tension force of the steel cable is mainly controlled, the control of the elongation value of the steel cable is assisted, the tension force of the steel cable is reflected through the data of the oil pressure sensor, and after the actual tension is finished, the tension force and the elongation value of the steel cable are within 5 percent of the theoretically calculated tension force and elongation value, so that the requirements of relevant specifications are met;
monitoring the stress and the structural deformation of the steel structure as an auxiliary monitoring means in the engineering tensioning process, selecting a rod piece with larger stress of the steel structure, monitoring the stress change by using a vibrating wire strain gauge, selecting a point in the middle of each truss string, monitoring and controlling the deformation, and monitoring the vertical deformation of the steel structure by using a level gauge.
7. The construction method for hoisting the steel structure roof of the beam string dome in the large-scale public building engineering according to claim 6, is characterized in that: the prestressed construction monitoring should run through the whole construction process, and the monitoring content of each construction stage is as follows:
firstly, before each tensioning, whether a test instrument works normally or not is checked, and an initial reading is read;
secondly, in the tensioning process of each batch, test instruments such as a dial indicator, a total station, a reflector, a vibrating wire strain gauge and the like cannot be moved, once the test instruments move, tensioning must be stopped, the test instruments are readjusted, tensioning can be carried out after the initial reading is read again, and the situation is recorded;
thirdly, after one batch is stretched, reading data in time, analyzing, comparing the data with a theoretical value, and continuously stretching the next batch after the structural condition is determined to be normal; if the problem exists, the problem is solved with related personnel in time;
fourthly, the testers need to be fixed, namely, dedicated personnel need to carry out testing work.
CN202010866482.4A 2020-08-25 2020-08-25 Construction method for hoisting steel structure roof of beam string dome in large-scale public building engineering Pending CN111980418A (en)

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