CN114398706A - Temperature equivalent simulation method and lower cross beam construction method - Google Patents
Temperature equivalent simulation method and lower cross beam construction method Download PDFInfo
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- CN114398706A CN114398706A CN202210042719.6A CN202210042719A CN114398706A CN 114398706 A CN114398706 A CN 114398706A CN 202210042719 A CN202210042719 A CN 202210042719A CN 114398706 A CN114398706 A CN 114398706A
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Abstract
The invention relates to the technical field of bridge construction, and discloses a temperature equivalent simulation method, which comprises the steps of presetting a support model, calculating first axial pressure, simulating a stress-free state of a bearing layer, calculating temperature and the influence of weight on the bearing layer; also discloses a lower cross beam construction method, which comprises the following steps: and calculating a first height by using a temperature equivalent simulation method, dividing the lower cross beam into a plurality of layers through the first height, and pouring according to the plurality of layers. The invention has the following advantages and effects: the application provides a method for actively stretching a steel pipe upright by adopting a temperature-rising load so as to enable the steel pipe upright to be actively jacked up and forcibly support a poured lower cross beam, and the poured lower cross beam is simulated to be in a stress-free state after being formed. Meanwhile, whether the bearing layer can bear the load is calculated on the basis, the result is closer to the actual situation, a large number of bearing mechanisms can be omitted by the construction method, the construction cost is low, and the design difficulty is small.
Description
Technical Field
The application relates to the technical field of bridge construction, in particular to a temperature equivalent simulation method and a lower cross beam construction method.
Background
At present, with the rapid development of traffic infrastructure in China, the bridge construction technology is different day by day, heavy load, large span, ultra-wide cable-stayed bridges and suspension bridges are in endless, the lower cross beam is used as a transverse connection of a main tower of the cable-stayed bridge and the suspension bridge and a supporting structure of a box girder, and the size of the lower cross beam is larger, so that a series of problems are caused: safety, difficult quality guarantee, large steel consumption of the cast-in-place support and the like.
The technology of 'tower beam synchronization, floor support and layered pouring' is generally adopted for pouring the lower cross beam of the large-volume main tower, and during concrete pouring, the solid section at the end part of the lower cross beam of the main tower is supported by a bracket. In the process of pouring the lower cross beam, the root of the lower tower column generates larger bending moment under the action of self weight, creeping formwork and wind load, besides, the concrete of the solid section at the end part of the lower cross beam also generates larger bending moment at the root of the lower tower column, and a temporary stay cable is generally arranged between the two tower columns to pull oppositely so as to reduce the bending moment at the root of the lower tower column in engineering.
The concrete load that is pouring when the bottom end rail is poured is born by the bottom end rail and the cast-in-place support that are poured the shaping for the first time jointly: and part of the pouring load is resisted by bending through the lower cross beam formed by the first pouring, and the rest of the pouring load is transmitted to the cast-in-place support in a local pressure bearing mode.
However, in the prior art, when the lower beam is poured in layers, the height of each pouring is more arbitrary, and the lower beam is generally divided into multiple layers according to a convention value to be poured, for example, 30%, 50% or 60% and the like. Under the condition that the general environmental temperature changes little, still can the effectual construction that carries on, in case the environmental temperature reduces, the steel pipe stand of lower beam support is because of cooling down the shrink, and then makes the holding power descend, leads to the partial lower beam of pouring shaping to appear the fracture scheduling problem. In order to avoid the problems, more steel structures are needed to support the lower cross beam in an auxiliary mode, and in order to support the auxiliary supporting structures, more supporting structures need to be additionally arranged on the tower column and the bearing platform of the bridge, so that the design difficulty is increased, and meanwhile, the consumption of steel is larger.
Disclosure of Invention
Aiming at the defects in the prior art, the application aims to provide a temperature equivalent simulation method and a lower beam construction method, which can directly and effectively determine the optimal layered position during layered casting and ensure that a bearing layer cast for the first time can bear the load during subsequent casting under any condition.
In order to achieve the above purposes, on one hand, the technical scheme is as follows:
the application provides a temperature equivalent simulation method, which is applied to the construction of a lower cross beam and comprises the following steps:
s1, presetting a lower beam support model according to construction requirements, and presetting a first height;
s2, after a bearing layer with a first height is poured, respectively calculating first axial pressure on each steel pipe stand column in the lower cross beam support;
s3, changing the temperature of each steel tube stand column in the lower beam support until the pressure borne by the top end of each steel tube stand column is equal to the calculated first axial pressure;
s4, calculating whether the bearing capacity of the bearing layer is the same as the load when the concrete is continuously poured to the design height of the lower cross beam, if the bearing capacity of the bearing layer is different from the load, adjusting the first height, and repeating the steps S2-S3 until the bearing capacity is the same as the load;
and S5, reducing the first temperature variables of all steel pipe stand columns in the lower cross beam support, calculating whether the bearing layer can bear the load, if not, increasing the first height, and calculating again until the bearing layer can bear the load.
Preferably, in step S4, the adjusting the first height includes the steps of:
when the bearing capacity of the bearing layer is larger than the load, the first height is reduced;
the first height is increased when the load-bearing capacity of the load-bearing layer is less than the load.
Preferably, the first temperature variable is a difference between a historical maximum air temperature and an average air temperature of the construction site.
The application also provides a lower beam construction method, which is applied to the lower beam of the bridge main tower and comprises the following steps:
determining a first height using a temperature equivalent simulation method as described above;
the method comprises the following steps that brackets are respectively installed on opposite side surfaces of a pair of tower columns of a bridge, a lower beam support is installed on a bearing platform of the bridge, and two ends of the top of the lower beam support are respectively lapped on the two brackets;
pouring the lower beam support for the first time to form a bearing layer with a first height;
after the bearing layer is formed, separating the bracket from the lower beam support;
and pouring the top surface of the bearing layer for the second time to the designed height of the lower cross beam to form the lower cross beam.
Preferably, when the first pouring is carried out, the method comprises the following steps:
a lower layer corrugated pipe is arranged at the top of the lower beam support;
penetrating a lower layer steel strand in the lower layer corrugated pipe, and tensioning the lower layer steel strand to a preset tension force;
and standing low side moulds on two sides of the lower cross beam support, and pouring concrete with a first height between the lower-layer corrugated pipe and the low side moulds to form a bearing layer.
Preferably, the step of pouring the concrete with the first height outside the lower layer corrugated pipe to form the bearing layer comprises the following steps:
reserving a first post-pouring belt in the span of the bearing layer;
erecting first end molds at two ends of the first post-cast strip, and pouring concrete among the low side mold, the first end molds and the lower-layer corrugated pipe;
after the concrete reaches the designed strength, removing the first end mold, and cleaning the end faces at the two ends of the first post-cast strip;
and pouring micro-expansion concrete at the first post-cast strip to form a bearing layer.
Preferably, when the second pouring is carried out, the method comprises the following steps:
tensioning the lower layer steel strand to a designed tension force;
cleaning the top surface of the bearing layer, installing an upper-layer corrugated pipe on the top surface of the bearing layer, and penetrating an upper-layer steel strand in the upper-layer corrugated pipe;
erecting a high side die on the top surface of the low side die, and pouring concrete between the high side die and the upper layer corrugated pipe to the designed height of the lower cross beam;
tensioning the upper layer steel strand to a designed tension force, and grouting in the upper layer corrugated pipe and the lower layer corrugated pipe;
and pouring anchor sealing concrete to form the lower cross beam.
Preferably, the step of pouring concrete between the high-side mould and the upper-layer corrugated pipe to the designed height of the lower cross beam comprises the following steps:
reserving a second post-cast strip in the lower cross beam span;
arranging middle-spanning end molds at two ends of the second post-cast strip;
pouring concrete among the high side mold, the midspan end mold and the upper layer corrugated pipe to the designed height of the lower cross beam;
after the concrete reaches the designed strength, removing the middle-span end mold and cleaning the end part of the second post-cast strip;
and pouring micro-expansion concrete at the second post-cast strip.
Preferably, the preset tension force is determined by the self weight of the lower tower column, wind load and vertical load of the equipment.
Preferably, the method further comprises the following steps:
and pouring a joint column on the top surface of the tower column, and reserving a hole for penetrating the prestressed steel strand in the joint column.
The beneficial effect that technical scheme that this application provided brought includes:
according to the temperature equivalent simulation method, the lower cross beam is always supported on the lower cross beam support from the fluid state of initial pouring to the process of gradual solidification, so that the lower cross beam still belongs to the stress-free state after being formed, meanwhile, the rigidity of the lower cross beam of the first pouring is much higher than that of the lower cross beam support, under the condition, the distribution problem of load between the lower cross beam of the first pouring and the lower cross beam support is complex, and if the lower cross beam is directly and simply simulated through software, the calculation result is probably not consistent with the actual stress state. The application provides a method for actively stretching a steel pipe upright by adopting a temperature-rising load so as to enable the steel pipe upright to be actively jacked up and forcibly support a poured lower cross beam, and the poured lower cross beam is simulated to be in a stress-free state after being formed. Meanwhile, whether the bearing layer can bear the load is calculated on the basis, and the result is closer to the actual situation.
By the aid of the lower cross beam construction method, the height of the bearing layer can be determined more accurately, so that the bearing layer can bear the weight of secondary pouring in a construction environment, a large number of bearing mechanisms can be omitted, construction cost is low, and design difficulty is small.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a front view of one embodiment of the present application.
Fig. 2 is a side view of the embodiment shown in fig. 1.
FIG. 3 is a schematic structural diagram of the platform in the embodiment shown in FIG. 1.
Reference numerals:
1. a bearing layer; 2. a first post-cast strip; 3. a second post-cast strip; 4. a tower column; 41. a bracket; 42. a bond post; 5. a lower beam support; 51. embedding parts; 52. a steel pipe upright post; 53. a distribution beam; 54. an anchor block; 6. a bearing platform.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
S1, presetting a lower beam support 5 model according to construction requirements, and presetting a first height.
Specifically, the lower beam support 5 model includes the diameter, height, number and position of the steel pipes in the lower beam support 5. The first predetermined height is typically selected in a predetermined manner, such as 25% lower beam thickness, and in typical embodiments, the entire calculation is performed in software for finite element calculations.
And S2, calculating the first axial pressure of each steel pipe upright 52 in the lower beam support 5 after the bearing layer 1 with the first height is poured.
Specifically, the first axial pressure applied to each steel pipe column 52 is actually equivalent to the bending moment applied to the bearing layer 1, and is used for simulating the state that the concrete of the bearing layer 1 is strong and supported on the lower cross beam support 5 after having the bending rigidity.
And S3, changing the temperature of each steel pipe upright 52 in the lower beam support 5 until the pressure applied to the top end of each steel pipe upright 52 is equal to the first axial pressure measured by the corresponding steel pipe upright 52 in the step S2.
Specifically, the bearing layer 1 is always supported on the lower cross beam bracket 5 from a fluid state of initial pouring to a process of gradual solidification, so that the bearing layer still belongs to a stress-free state after being molded; since the rigidity of the formed lower cross beam is much higher than that of the steel pipe upright 52, if simulation is carried out through software, the calculation result is completely inconsistent with the actual stress state. In order to solve the problem, a method for actively stretching the steel pipe upright 52 by adopting a temperature-rising load so as to enable the steel pipe upright 52 to actively jack up and forcibly support the poured lower cross beam is provided, and the poured lower cross beam is in a stress-free stress state after simulation forming, so that the method is closer to reality than direct calculation.
Generally, the step can calculate the specific temperature amount to be adjusted by the following method:
a relatively small temperature is preset, for example, in this embodiment, all the steel tube columns 52 are set to 20 ℃, and then the required degree of change is calculated according to the following formula:
wherein N is the difference between the top pressure of the steel pipe column 52 and the first axial pressure, α is the expansion coefficient of the steel pipe column 52, a is the sectional area of the steel pipe column 52, and E is the elastic modulus of the steel pipe column 52. However, the result calculated by this formula is not completely accurate, and the temperature needs to be finely adjusted after the temperature of the steel pipe columns 52 is changed, so that the result that the pressure applied to the top end of each steel pipe column 52 is equal to the first axial pressure of the corresponding steel pipe column 52 measured in step S2 can be obtained. Taking one steel pipe in the example shown in fig. 1 as an example, Δ t is calculated to be 15 ℃.
S4, calculating whether the bearing capacity of the bearing layer 1 is the same as the load when the concrete is continuously poured to the design height of the lower cross beam, if the bearing capacity of the bearing layer 1 is different from the load, adjusting the first height, and repeating the steps S2-S3 until the bearing capacity of the bearing layer 1 is the same as the load.
Specifically, whether the bearing capacity of the bearing layer 1 is the same as the load or not mainly aims at adjusting the thickness of the bearing layer 1 to a state of just supporting a lower cross beam which is poured subsequently, namely finding out the lower limit of the thickness of the bearing layer 1.
In some preferred embodiments, the step S4 further includes the following steps:
when the load-bearing capacity of the load-bearing layer 1 is greater than the load, the first height is lowered. When the load-bearing capacity of the load-bearing layer 1 is less than the load, the first height is increased.
Specifically, when adjusting the first height, the lower limit of the thickness of the bearing layer 1 may be determined by multiple approximation, for example, by bisection, and the value of the first height decreased or increased each time is equal to half of the original value.
And S5, reducing the first temperature variable of all the steel pipe upright columns 52 in the lower cross beam support 5, calculating whether the bearing layer 1 can bear the load, if not, increasing the first height, and repeating the step S5 until the bearing layer 1 can bear the load.
Specifically, during simulation, all the columns should simultaneously reduce the same temperature variation to reflect the actual effect that the temperature variation causes the steel pipe columns 52 to contract, thereby causing the reduction of the bearing effect on the bearing layer 1. In a preferred embodiment, the first temperature variable is a difference between a historical maximum air temperature and an average air temperature of the construction site.
The application also provides a lower beam construction method, which is applied to the lower beam of the bridge main tower and comprises the following steps:
A1. the first height is determined using the temperature equivalent simulation method described above. In the embodiment shown in fig. 1, the height of the lower beam is 11.6m, the width is 13m, the first height is 7.8m, and the height of the lower beam in the second pouring is 3.8 m.
A2. Corbels 41 are respectively arranged on the opposite side surfaces of a pair of tower columns 4 of the bridge, a lower beam support 5 is arranged on a bearing platform 6 of the bridge, and two ends of the top of the lower beam support 5 are respectively lapped on the two corbels 41.
Specifically, in a general embodiment, as shown in fig. 1, the lower beam support 5 includes a plurality of steel pipe columns 52 and a distribution beam 53 at the top, the steel pipe columns 52 are approximately vertical, the steel pipe columns 52 near both sides have a certain inclination, the adjacent steel pipe columns 52 are connected by a connection system, the bottom ends of the steel pipe columns 52 are mounted on the bearing platform 6 through embedded parts 51, both ends of the distribution beam 53 are connected to the corbels 41, meanwhile, for more even load distribution, the distribution beam 53 is divided into three layers, as shown in fig. 2, the first layer is a whole plate-shaped structure arranged in the transverse direction, the second layer is a plurality of beams arranged in the longitudinal direction in the transverse direction, and mutually arranged on the top surface of the first layer in the longitudinal bridge direction, and the third layer is arranged in the transverse bridge direction, for direct bearing of concrete, the third layer is generally larger in size than the lower beam to be cast, so as to facilitate installation of various construction equipment. Before construction, the steel pipe columns 52 need to be pre-pressed, so that gaps between the steel pipe columns 52 are reduced, the pre-pressing is carried out through the anchor seats 54, the anchor seats 54 are partially embedded in the bearing platform, and before the lower cross beam is constructed, the anchor seats 54 and the distribution beams 53 need to be connected and tensioned through steel strands, so that the gaps between the steel pipe columns 52 are eliminated.
The bracket 41 is used for assisting the bearing effect during the first pouring, and the main bearing position is a place where the steel pipe upright 52 in the lower beam support 5 is not easy to reach, such as near the connection point of the lower beam and the tower column 4, so as to ensure the stability of the lower beam support 5, mainly in order to avoid unexpected situations that the load of the lower beam exceeds the expectation.
A3. And pouring the lower cross beam bracket 5 for the first time to form the bearing layer 1 with the first height.
Specifically, as can be seen in fig. 2, the lower beam is cast to a size slightly smaller than the distribution beam 53 of the lower beam support 5, so as to facilitate installation of the formwork of the lower beam. In the embodiment shown in fig. 1, it is desirable that the strength of the carrier layer 1 is up to 2.5 Mpa.
A4. After the support layer 1 is formed, the bracket 41 is separated from the support layer 1.
Specifically, the method for separating the bracket 41 from the bearing layer 1 is performed according to the design mode of the bracket 41, generally, a sand bag or a cushion block is arranged at the top of the bracket 41, the sand bag and the cushion block are used for supporting the distribution beam 53 of the lower beam support 5, and when the bracket 41 needs to be removed in the subsequent step, the sand in the sand bag is discharged or the cushion block is cut off.
A5. And pouring the top surface of the bearing layer 1 for the second time to the design height of the lower cross beam to form the lower cross beam.
In the prior art, a temporary guy cable is generally arranged between two towers 4 to pull oppositely so as to reduce the bending moment of the root of the lower tower 4. However, the installed temporary stay cable is easily damaged by welding slag, falling blocks and the like generated in the construction of the main tower, particularly, when the lower cross beam of the large-span large-section main tower is constructed, the tension of the temporary stay cable is often large, sparks are large during welding, and the temporary stay cable has great safety problems in the tension construction of the temporary stay cable and the protection after the construction.
Therefore, in some preferred embodiments, the following steps are further included:
A31. and a lower-layer corrugated pipe is arranged at the top of the lower cross beam bracket 5.
A32. And (4) penetrating a lower layer steel strand in the lower layer corrugated pipe, and tensioning the lower layer steel strand to a preset tensioning force.
A33. And standing low-side moulds on two sides of the lower cross beam support 5, and pouring concrete with a first height between the lower-layer corrugated pipe and the low-side moulds to form a bearing layer 1.
Specifically, in step a32, a structure for tensioning is generally arranged on the tower column 4, the lower layer of steel strand passes through the corresponding structure, a center-penetrating jack is arranged on the outer side of the tower column 4, the lower layer of steel strand is connected to the pushing end of the center-penetrating jack, and forces are simultaneously applied to the two sides until the tension of the steel strand reaches a preset tension. The predetermined tension is generally less than the final desired design tension, typically 20-40% of the design tension. Simultaneously, the steel strand wires for tensioning of this embodiment sets up in the inside of bottom end rail, can not receive hazards such as external spark, debris and residue and influence, and the security improves greatly.
Preferably, the preset tension force is determined by the self weight of the lower tower column 4, the wind load and the vertical load of the equipment. The vertical load of the equipment is the load generated in the vertical direction of the equipment for construction, and generally comprises the dead weight of the creeping formwork and the bending moment generated by the load born by the bracket 41 to the root of the tower column 4
The preset tension force has the calculation formula as follows:
where Σ MWind powerBending moment, sigma M, to the tower 4 root, generated for wind loadsTower columnBending moment, sigma M, to the root of the tower column 4 generated by the self weight of the tower column 4DeviceBending moment generated to the root of the tower column 4 by construction equipment. And H is the height of the lower layer of steel strand from the ground.
In carrying out step a33 of placing concrete of a first height to form the load-bearing layer 1, a preferred embodiment comprises the steps of:
A331. and reserving a first post-pouring belt 2 in the span of the bearing layer 1. Specifically, in the embodiment shown in fig. 1, the width of the first post-cast strip 2 is 2.5 m.
A332. And erecting first end molds at two ends of the first post-cast strip 2, and pouring concrete among the low side mold, the first end molds and the lower layer corrugated pipe.
A333. And after the concrete reaches the designed strength, removing the first end mold and cleaning the end surfaces at the two ends of the first post-cast strip 2. Specifically, when the end surface of the first post-cast strip 2 is cleaned, the adhesive force of the end part needs to be increased by means of roughening cleaning.
A334. And pouring micro-expansion concrete at the first post-pouring belt 2 to form a bearing layer 1.
Specifically, the micro-expansion concrete is early-strength concrete capable of compensating shrinkage, and is combined with a post-cast strip, so that the problem of cracking of the lower cross beam is avoided.
In order to avoid the deformation of the tower column 4 caused by the increased load during the secondary casting, in some preferred embodiments, the step a5 further includes the following steps:
A51. and tensioning the lower layer steel strand to a designed tension force. Specifically, the design tension force value is provided by general construction requirements, and compared with the preset tension force, the design tension force also considers the bending moment of the lower cross beam and the subsequent bridge structure on the root of the tower column 4.
A52. The top surface of the bearing layer 1 is cleaned, an upper-layer corrugated pipe is arranged on the top surface of the bearing layer 1, and an upper-layer steel strand penetrates through the upper-layer corrugated pipe. Specifically, clearance 1 top surface on bearing layer generally need wait for bearing layer 1 and just begin to go on after reaching certain intensity, and the purpose of clearance 1 top surface on bearing layer is the debris of cleaing away 1 top surface on bearing layer on the one hand, prevents to disturb subsequent pouring, and on the other hand carries out certain improvement increase concrete and the viscous power between the bearing layer 1 when pouring for the second time to bearing layer 1 top surface, and this embodiment is through the mode clearance 1 top surface of chisel hair.
And a center-penetrating jack is arranged at a position corresponding to the upper layer steel strand, the upper layer steel strand is connected to a pushing end corresponding to the center-penetrating jack, and the upper layer steel strand only keeps a tight state after being installed and is not tensioned. The steel strand wires for tensioning of this embodiment sets up in the inside of bottom end rail, can not receive hazards such as external spark, debris and residue and influence, and the security improves greatly.
A53. And erecting a high side die on the top surface of the low side die, and pouring concrete between the high side die and the upper layer corrugated pipe to the designed height of the lower cross beam. Specifically, multiple-layer pouring can be performed under the condition of a severe construction environment, but the top surface of the formed part needs to be cleaned and roughened during each pouring.
A54. And tensioning the upper layer steel strand to a designed tension force, and grouting in the upper layer corrugated pipe and the lower layer corrugated pipe. Specifically, the corrugated pipe is generally grouted in a hole reserved at the anchor backing plate.
A55. And pouring anchor sealing concrete to form the lower cross beam.
In order to prevent cracking during the second casting, in some preferred embodiments, step A53 further comprises the following steps
A531. And reserving a second post-cast strip 3 in the lower cross beam span. Specifically, in the present embodiment, the width of the second post-cast strip 3 is equivalent to the width of the first post-cast strip 2.
A532. And middle-spanning end molds are arranged at two ends of the second post-cast strip 3.
A533. And pouring concrete among the high side die, the midspan end die and the upper-layer corrugated pipe to the designed height of the lower cross beam.
A534. And after the concrete reaches the designed strength, removing the middle-span end mold and cleaning the end part of the second post-cast strip 3. Specifically, when clearing up 3 tip of second post-cast strip, not only need clear up the not good fragile part that condenses of tip, still need carry out the chisel hair clearance to second post-cast strip 3, increase tip to the adhesion of little inflation concrete.
A535. And pouring micro-expansion concrete at the second post-cast strip 3.
In some preferred embodiments, in order to reduce the number and weight of the construction structure, before constructing the lower cross beam, the following steps are further performed:
and pouring the joint column 42 on the top surface of the tower column 4, and reserving a hole for penetrating the prestressed steel strand in the joint column 42. In particular, referring to fig. 3, the coupling studs 42 are dimensioned according to the shape of the lower beam, typically forming part of the lower beam after construction is complete, and in the embodiment shown in fig. 1 the coupling studs 42 are the ends of the load-bearing layer 1. And the joint column 42 is poured in advance, so that the steel structure for construction and bearing can be reduced, and the construction cost is reduced.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
It is noted that, in the present application, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is merely exemplary of the present application and is presented to enable those skilled in the art to understand and practice the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A temperature equivalent simulation method is applied to lower beam construction and is characterized by comprising the following steps:
s1, presetting a lower beam support (5) model according to construction requirements, and presetting a first height;
s2, after the bearing layer (1) with the first height is poured, respectively calculating first axial pressure on each steel pipe upright post (52) in the lower cross beam support (5);
s3, changing the temperature of each steel pipe column (52) in the lower beam support (5) until the pressure borne by the top end of each steel pipe column (52) is equal to the calculated first axial pressure;
s4, calculating whether the bearing capacity of the bearing layer (1) is the same as the load when the concrete is continuously poured to the design height of the lower cross beam, if the bearing capacity of the bearing layer is different from the load, adjusting the first height, and repeating the steps S2-S3 until the bearing capacity is the same as the load;
s5, reducing the first temperature variable of all steel pipe columns (52) in the lower cross beam support (5), calculating whether the bearing layer (1) can bear the load, if not, increasing the first height, and calculating again until the bearing layer (1) can bear the load.
2. The method for simulating temperature equivalence of claim 1, wherein the step S4, the adjusting the first height comprises the steps of:
when the bearing capacity of the bearing layer (1) is larger than the load, the first height is reduced;
when the load-bearing capacity of the load-bearing layer (1) is less than the load, the first height is increased.
3. A temperature equivalence simulation method according to claim 1, wherein the first temperature variable is a difference between a historical maximum air temperature and an average air temperature at a construction site.
4. A lower cross beam construction method is applied to a lower cross beam of a bridge main tower and is characterized by comprising the following steps:
determining a first height using a temperature equivalent simulation method as claimed in claim 1;
corbels (41) are respectively installed on opposite side surfaces of a pair of tower columns (4) of the bridge, a lower beam support (5) is installed on a bearing platform (6) of the bridge, and two ends of the top of the lower beam support (5) are respectively lapped on the two corbels (41);
pouring the lower beam support (5) for the first time to form a bearing layer (1) with a first height;
after the bearing layer (1) is formed, separating the bracket (41) from the lower beam bracket (5);
and (4) pouring the top surface of the bearing layer (1) for the second time to the designed height of the lower cross beam to form the lower cross beam.
5. A lower beam construction method according to claim 4, wherein the first pouring comprises the following steps:
a lower layer corrugated pipe is arranged at the top of the lower beam support (5);
penetrating a lower layer steel strand in the lower layer corrugated pipe, and tensioning the lower layer steel strand to a preset tension force;
and standing low side moulds on two sides of the lower cross beam support (5), and pouring concrete with a first height between the lower-layer corrugated pipe and the low side moulds to form a bearing layer (1).
6. A method for constructing a lower beam according to claim 5, wherein the step of pouring concrete of a first height outside the lower corrugated pipe to form the bearing layer (1) comprises the following steps:
reserving a first post-pouring belt (2) in the span of the bearing layer (1);
erecting first end molds at two ends of the first post-cast strip (2), and pouring concrete among the low side mold, the first end molds and the lower layer corrugated pipe;
after the concrete reaches the designed strength, the first end mold is dismantled, and the end faces of the two ends of the first post-cast strip (2) are cleaned;
and pouring micro-expansion concrete at the first post-cast strip (2) to form a bearing layer (1).
7. The method for constructing the lower cross beam according to claim 5, wherein the second pouring comprises the following steps:
tensioning the lower layer steel strand to a designed tension force;
cleaning the top surface of the bearing layer (1), installing an upper-layer corrugated pipe on the top surface of the bearing layer (1), and penetrating an upper-layer steel strand in the upper-layer corrugated pipe;
erecting a high side die on the top surface of the low side die, and pouring concrete between the high side die and the upper layer corrugated pipe to the designed height of the lower cross beam;
tensioning the upper layer steel strand to a designed tension force, and grouting in the upper layer corrugated pipe and the lower layer corrugated pipe;
and pouring anchor sealing concrete to form the lower cross beam.
8. A method for constructing a lower beam according to claim 7, wherein the step of pouring concrete between the high side forms and the upper corrugated pipe to the designed height of the lower beam comprises the steps of:
reserving a second post-cast strip (3) in the lower cross beam span;
arranging middle-spanning end molds at two ends of the second post-cast strip (3);
pouring concrete among the high side mold, the midspan end mold and the upper layer corrugated pipe to the designed height of the lower cross beam;
after the concrete reaches the designed strength, removing the middle-span end mold and cleaning the end part of the second post-cast strip (3);
and pouring micro-expansion concrete at the second post-cast strip (3).
9. The lower beam construction method according to claim 5, wherein: the preset tension force is determined by the self weight of the lower tower column (4), wind load and vertical load of the equipment.
10. The lower beam construction method according to claim 4, further comprising the steps of:
and pouring a joint column (42) on the top surface of the tower column (4), and reserving a hole for penetrating the prestressed steel strand in the joint column (42).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115828675A (en) * | 2022-11-17 | 2023-03-21 | 中交建筑集团有限公司 | Leaning tower stress control method based on back support system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115828675A (en) * | 2022-11-17 | 2023-03-21 | 中交建筑集团有限公司 | Leaning tower stress control method based on back support system |
| CN115828675B (en) * | 2022-11-17 | 2023-06-20 | 中交建筑集团有限公司 | Inclined tower stress control method based on back support system |
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