A temperature equivalent simulation method and a lower crossbeam construction method

Abstract

The present invention relates to the technical field of bridge construction, and discloses a temperature equivalent simulation method, including presetting a support model, calculating a first axial pressure, simulating the stress-free state of a load-bearing layer, and calculating the influence of temperature and weight on the load-bearing layer; also discloses a construction method for a lower cross beam, including: calculating a first height by using the temperature equivalent simulation method, dividing the lower cross beam into multiple layers according to the first height, and pouring in multiple layers. The present invention has the following advantages and effects: The present application proposes a method of actively stretching the steel pipe columns by using a temperature rise load, so that the steel pipe columns actively push up and forcibly support the already cast lower cross beam, simulating the stress-free state of the already cast lower cross beam after forming. At the same time, on this basis, the calculation of whether the load-bearing layer can bear the load is carried out, and the result is closer to the actual situation. Moreover, this construction method can save a large number of load-bearing mechanisms, with low construction costs and small design difficulties.

Description

Technical Field

[0001] This application relates to the technical field of bridge construction, and specifically relates to a temperature equivalent simulation method and a lower crossbeam construction method. Background Art

[0002] At present, with the rapid development of China's transportation infrastructure, bridge construction technologies are advancing by leaps and bounds, and heavy-load, long-span, extra-wide cable-stayed bridges and suspension bridges are emerging in an endless stream. As the transverse connection of the main towers of cable-stayed bridges and suspension bridges and the support structure of box girders, the lower crossbeam is getting larger in size, which brings a series of problems: it is difficult to ensure safety and quality, and the steel consumption of in-situ supports is large.

[0003] For the casting of the lower crossbeam of large-volume main towers, the "tower-beam synchronization + floor support + layered casting" process is generally adopted. When casting concrete, the solid section at the end of the lower crossbeam of the main tower is supported by a bracket. During the casting of the lower crossbeam, in addition to the large bending moment generated at the root of the lower tower column under its own weight, climbing formwork, and wind load, the concrete in the solid section at the end of the lower crossbeam will also generate a large bending moment at the root of the lower tower column. Generally, temporary stay cables are set between the two tower columns for tensioning to reduce the bending moment at the root of the lower tower column.

[0004] During the casting of the lower crossbeam, the load of the concrete being cast is jointly borne by the lower crossbeam formed by the first casting and the in-situ support: part of the casting load is resisted by the bending of the lower crossbeam formed by the first casting, and the remaining casting load is transferred to the in-situ support by means of local bearing.

[0005] However, in the prior art, during layered casting, the height of each casting is rather arbitrary. Generally, the lower crossbeam is divided into multiple layers for casting according to a conventional value, such as 30%, 50%, or 60%, etc. In the case of little change in the general ambient temperature, construction can still be effectively carried out. Once the ambient temperature drops, the steel pipe columns of the lower crossbeam support will contract due to temperature reduction, thereby reducing the supporting force, resulting in problems such as cracking in the partially cast lower crossbeam. To avoid these problems, more steel structures are required to assist in supporting the lower crossbeam. To support these auxiliary support structures, more support structures need to be installed at the tower columns and caissons of the bridge, increasing the design difficulty and consuming more steel. Summary of the Invention

[0006] Aiming at the defects existing in the prior art, the purpose of this application is to provide a temperature equivalent simulation method and a lower crossbeam construction method, which can directly and effectively determine the optimal layered position during layered casting, and ensure that the load-bearing layer of the first casting can bear the load during subsequent casting under any circumstances.

[0007] To achieve the above object, on the one hand, the technical solution adopted is:

[0008] The present application provides a temperature equivalent simulation method, which is applied to the construction of the lower crossbeam and includes the following steps:

[0009] S1. Preset the lower crossbeam support model according to the construction requirements and preset the first height;

[0010] S2. After pouring the load-bearing layer at the first height, calculate the first axial pressure received by each steel pipe column in the lower crossbeam support respectively;

[0011] S3. Change the temperature of each steel pipe column in the lower crossbeam support until the pressure received by the top of each steel pipe column is equal to the calculated first axial pressure;

[0012] S4. Calculate whether the load-bearing capacity of the load-bearing layer is the same as the load when the concrete is continuously poured to the designed height of the lower crossbeam. If not, adjust the first height and repeat steps S2 - S3 until the load-bearing capacity is the same as the load;

[0013] S5. Reduce the first temperature variable of all steel pipe columns in the lower crossbeam support and calculate whether the load-bearing layer can bear the load. If not, increase the first height and recalculate until the load-bearing layer can bear the load.

[0014] Preferably, in step S4, adjusting the first height includes the following steps:

[0015] When the load-bearing capacity of the load-bearing layer is greater than the load, reduce the first height;

[0016] When the load-bearing capacity of the load-bearing layer is less than the load, increase the first height.

[0017] Preferably, the first temperature variable is the difference between the historical highest temperature and the average temperature at the construction site.

[0018] The present application also provides a construction method for the lower crossbeam, which is applied to the lower crossbeam of the bridge main tower and includes the following steps:

[0019] Use the temperature equivalent simulation method as described above to determine the first height;

[0020] Install brackets on the opposite sides of a pair of tower columns of the bridge, and at the same time install the lower crossbeam support on the bridge abutment. The two ends of the top of the lower crossbeam support are respectively lapped on the two brackets;

[0021] Carry out the first pouring of the lower crossbeam support to form a load-bearing layer at the first height;

[0022] After the load-bearing layer is formed, separate the brackets and the lower crossbeam support;

[0023] Carry out the second pouring on the top surface of the load-bearing layer to the designed height of the lower crossbeam to form the lower crossbeam.

[0024] Preferably, when performing the first pouring, the following steps are included:

[0025] Install the lower corrugated pipe on the top of the lower crossbeam support;

[0026] Thread the lower steel strand into the lower corrugated pipe and tension the lower steel strand to the preset tensile force;

[0027] Set up the lower side formwork on both sides of the lower crossbeam support, and pour concrete of the first height between the lower corrugated pipe and the lower side formwork to form the load-bearing layer.

[0028] Preferably, pouring concrete of the first height outside the lower corrugated pipe to form the load-bearing layer includes the following steps:

[0029] Reserve the first post-cast strip at the mid-span of the load-bearing layer;

[0030] Set up the first end formwork at both ends of the first post-cast strip, and pour concrete between the lower side formwork, the first end formwork and the lower corrugated pipe;

[0031] After the concrete reaches the design strength, remove the first end formwork and clean the end faces at both ends of the first post-cast strip;

[0032] Pour micro-expansion concrete at the first post-cast strip to form the load-bearing layer.

[0033] Preferably, when performing the second pouring, the following steps are included:

[0034] Tension the lower steel strand to the design tensile force;

[0035] Clean the top surface of the load-bearing layer, install the upper corrugated pipe on the top surface of the load-bearing layer, and thread the upper steel strand into the upper corrugated pipe;

[0036] Erect the upper side formwork on the top surface of the lower side formwork, and pour concrete between the upper side formwork and the upper corrugated pipe to the design height of the lower crossbeam;

[0037] Tension the upper steel strand to the design tensile force, and grout in the upper corrugated pipe and the lower corrugated pipe;

[0038] Pour the anchor-sealing concrete to form the lower crossbeam.

[0039] Preferably, pouring concrete between the upper side formwork and the upper corrugated pipe to the design height of the lower crossbeam includes the following steps:

[0040] Reserve the second post-cast strip at the mid-span of the lower crossbeam;

[0041] Set up the mid-span end formwork at both ends of the second post-cast strip;

[0042] Pour concrete between the upper side formwork, the mid-span end formwork and the upper corrugated pipe to the design height of the lower crossbeam;

[0043] After the concrete reaches the designed strength, remove the end formwork at the mid-span and clean the end of the second post-cast strip.

[0044] Pour slightly expanding concrete at the second post-cast strip.

[0045] Preferably, the preset tensile force is determined by the self-weight of the lower tower column, wind load, and vertical load of the equipment.

[0046] Preferably, the following steps are further included:

[0047] Pour the connecting column on the top surface of the tower column, and reserve holes for passing prestressed steel strands in the connecting column.

[0048] The beneficial effects brought by the technical solution provided in this application include:

[0049] In the temperature equivalent simulation method of this application, since the lower crossbeam is in a fluid state from the beginning of pouring to the process of gradually solidifying, it is always supported on the lower crossbeam support. Therefore, after it is formed, it still belongs to a stress-free state. At the same time, because the stiffness of the first-poured lower crossbeam is much larger than that of the lower crossbeam support, in this case, the load distribution problem between the first-poured lower crossbeam and the lower crossbeam support is relatively complex. If simple simulation is directly carried out through software, the calculation result is very likely to be completely inconsistent with the actual stress state. This application proposes to use the heating load to actively stretch the steel pipe column, so as to make the steel pipe column actively jack up and forcibly support the already poured and formed lower crossbeam, simulating the stress-free state of the already poured lower crossbeam after forming. At the same time, on this basis, the calculation of whether the bearing layer can bear the load is carried out, and the result is closer to the actual situation.

[0050] And by using the lower crossbeam construction method provided in this application, because the height of the bearing layer can be determined more accurately, the bearing layer can bear the weight of the second pouring in the construction environment. Therefore, a large number of bearing mechanisms can be omitted in this construction method, with low construction cost and small design difficulty. Description of the Drawings

[0051] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0052] Figure 1 It is the front view of an embodiment in this application.

[0053] Figure 2 It is Figure 1 the side view of the shown embodiment.

[0054] Figure 3For Figure 1 The structural schematic diagram of the bearing platform in the illustrated embodiment.

[0055] Reference numerals:

[0056] 1, load-bearing layer; 2, first post-cast strip; 3, second post-cast strip; 4, tower column; 41, corbel; 42, joint column; 5, lower crossbeam support; 51, embedded part; 52, steel pipe column; 53, distribution beam; 54, anchor seat; 6, bearing platform. Specific embodiments

[0057] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0058] S1. Preset the model of the lower crossbeam support 5 according to the construction requirements, and preset the first height.

[0059] Specifically, the model of the lower crossbeam support 5 includes the diameter, height, quantity and position of the steel pipes in the lower crossbeam support 5. The first preset height generally selects a commonly used division method, such as 25% of the thickness of the lower crossbeam. In general embodiments, the entire calculation is carried out in finite element calculation software.

[0060] S2. Calculate the first axial pressure received by each steel pipe column 52 in the lower crossbeam support 5 after pouring the load-bearing layer 1 of the first height.

[0061] Specifically, the first axial pressure received by each steel pipe column 52 is actually equivalent to the bending moment received by the load-bearing layer 1, and is used to simulate the state of the load-bearing layer 1 after the concrete is strengthened and has bending stiffness and is supported on the lower crossbeam support 5.

[0062] S3. Change the temperature of each steel pipe column 52 in the lower crossbeam support 5 until the pressure received by the top of each steel pipe column 52 is equal to the first axial pressure measured by the corresponding steel pipe column 52 in step S2.

[0063] Specifically, since the load-bearing layer 1 is in a fluid state when it is first poured and gradually solidifies, it is always supported on the lower crossbeam support 5. Therefore, after it is formed, it is still in a stress-free state. However, since the stiffness of the formed lower crossbeam is much greater than that of the steel pipe column 52, if simulated by software, the calculation results will be completely inconsistent with the actual stress state. To solve this problem, a method of actively stretching the steel pipe column 52 by applying a temperature rise load is proposed, so that the steel pipe column 52 actively jacks up and forcibly supports the formed lower crossbeam, simulating the stress-free state of the formed lower crossbeam after pouring, which is closer to reality than direct calculation.

[0064] Generally speaking, in this step, the specific temperature change amount that needs to be adjusted can be calculated by the following method:

[0065] A relatively small temperature is preset first. For example, in this embodiment, it can be set that all the steel pipe columns 52 are at 20°C, and then the degree of change required is calculated according to the following formula:

[0066]

[0067] Where N is the difference between the pressure at the top 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 cross-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. After changing the temperature of the steel pipe column 52, the temperature still needs to be finely adjusted, and finally the result that the pressure received at the top of each steel pipe column 52 is equal to the first axial pressure measured by the corresponding steel pipe column 52 in step S2 can be obtained. Taking Figure 1 a steel pipe in the middle of the illustrated embodiment as an example, where Δt = 15°C is calculated.

[0068] S4. Calculate whether the load-bearing capacity of the load-bearing layer 1 is the same as the load when the concrete is continuously poured to the designed height of the lower crossbeam. If not, adjust the first height and repeat steps S2 - S3 until the load-bearing capacity of the load-bearing layer 1 is the same as the load.

[0069] Specifically, the main purpose of whether the load-bearing capacity of the load-bearing layer 1 is the same as the load is to adjust the thickness of the load-bearing layer 1 to just support the subsequent poured lower crossbeam, that is, to find the lower limit of the thickness of the load-bearing layer 1.

[0070] In some preferred embodiments, step S4 further includes the following steps:

[0071] When the load-bearing capacity of the load-bearing layer 1 is greater than the load, lower the first height. When the load-bearing capacity of the load-bearing layer 1 is less than the load, increase the first height.

[0072] Specifically, when adjusting the first height, the lower limit of the thickness of the bearing layer 1 can be determined by means of multiple approximations. For example, the dichotomy method can be used, and the value of the first height decreased or increased each time is equal to half of the original value.

[0073] S5. Reduce the first temperature variable for all the steel pipe columns 52 in the lower crossbeam support 5, and calculate whether the bearing layer 1 can bear the load. If not, increase the first height and repeat step S5 until the bearing layer 1 can bear the load.

[0074] Specifically, during the simulation, all the columns should reduce the same temperature variable simultaneously to reflect the actual effect that the shrinkage of the steel pipe columns 52 caused by the change in air temperature leads to the decline in the load-bearing effect of the bearing layer 1. In a preferred embodiment, the first temperature variable is the difference between the historical highest temperature and the average temperature at the construction site.

[0075] The present application also provides a construction method for the lower crossbeam, which is applied to the lower crossbeam of the main tower of the bridge and includes the following steps:

[0076] A1. Determine the first height by using the aforementioned temperature equivalent simulation method. In the Figure 1 illustrated embodiment, the height of the lower crossbeam is 11.6 m, the width is 13 m, the first height is 7.8 m, and the height of the second pouring of the lower crossbeam is 3.8 m.

[0077] A2. Install brackets 41 on the opposite sides of a pair of tower columns 4 of the bridge respectively, and at the same time install the lower crossbeam support 5 on the bridge abutment 6. The two ends of the top of the lower crossbeam support 5 are respectively lapped on the two brackets 41.

[0078] Specifically, in a general embodiment, as Figure 1 illustrated, the lower crossbeam support 5 includes multiple steel pipe columns 52 and a distribution beam 53 at the top. The steel pipe columns 52 are nearly vertical, and the steel pipe columns 52 near both sides have a certain slope. The adjacent steel pipe columns 52 are connected by connecting systems. The bottom ends of the steel pipe columns 52 are installed on the abutment 6 through embedded parts 51. The two ends of the distribution beam 53 are lapped on the brackets 41. At the same time, in order to distribute the load more evenly, the distribution beam 53 is divided into three layers, which can be seen in Figure 2 . The first layer is a whole plate-like structure arranged transversely to the bridge axis. The second layer is multiple beams arranged transversely to the bridge axis in the length direction and are evenly arranged longitudinally to the bridge axis on the top surface of the first layer. The third layer is arranged transversely to the bridge axis and is used to directly bear the concrete. Generally, the size of the third layer is larger than that of the lower crossbeam to be poured, so as to facilitate the installation of various construction equipment. Before construction, it is necessary to preload the steel pipe columns 52 to reduce the gaps between the steel pipe columns 52. The preloading is carried out through the anchor seats 54. Part of the anchor seats 54 is buried in the abutment. Before the construction of the lower crossbeam, it is necessary to connect the anchor seats 54 and the distribution beam 53 with steel strands and tighten them to eliminate the gaps between the steel pipe columns 52.

[0079] The corbel 41 is used to assist in bearing the load during the first pouring. The main load-bearing positions are places that are not easily reached by the steel pipe columns 52 in the lower crossbeam support 5, such as near the connection point between the lower crossbeam and the tower column 4, to ensure the stability of the lower crossbeam support 5, mainly to avoid the load of the lower crossbeam exceeding the expectation due to unexpected situations.

[0080] A3. Conduct the first pouring on the lower crossbeam support 5 to form a load-bearing layer 1 with a first height.

[0081] Specifically, reference can be made to Figure 2 , the size of the lower crossbeam during pouring is slightly smaller than the distribution beam 53 of the lower crossbeam support 5 to facilitate the installation of the formwork of the lower crossbeam. In Figure 1 the embodiment shown, the strength of the load-bearing layer 1 needs to reach 2.5 Mpa.

[0082] A4. After the load-bearing layer 1 is formed, separate the corbel 41 from the load-bearing layer 1.

[0083] Specifically, the method of separating the corbel 41 from the load-bearing layer 1 should be carried out according to the designed method of the corbel 41. Generally, sandbags or cushion blocks are arranged on the top of the corbel 41. During use, the distribution beam 53 of the lower crossbeam support 5 is supported by the sandbags and cushion blocks. When the corbel 41 needs to be removed in the subsequent steps, just release the sand in the sandbag or cut off the cushion block.

[0084] A5. Conduct the second pouring on the top surface of the load-bearing layer 1 to the designed height of the lower crossbeam to form the lower crossbeam.

[0085] In the prior art, temporary stay cables are generally arranged between the two tower columns 4 for tensioning to reduce the bending moment at the root of the lower tower column 4. However, the installed temporary stay cables are easily damaged by welding slag, falling blocks, etc. generated during the construction of the main tower. Especially during the construction of the lower crossbeam of a large-span giant-section main tower, the tension of the temporary stay cables is often large, and the sparks during welding work are large, which pose great safety problems for the tensioning construction and post-construction protection of the temporary stay cables.

[0086] Therefore, in some preferred embodiments, the following steps are further included:

[0087] A31. Install the lower-layer corrugated pipe on the top of the lower crossbeam support 5.

[0088] A32. Thread the lower-layer steel strand into the lower-layer corrugated pipe and tension the lower-layer steel strand to the preset tensile force.

[0089] A33. Erect the low-side formwork on both sides of the lower crossbeam support 5, and pour concrete with a first height between the lower-layer corrugated pipe and the low-side formwork to form the load-bearing layer 1.

[0090] Specifically, when performing step A32, generally, a structure for tensioning is provided on the tower column 4. The lower-layer steel strands are passed through the corresponding structure, and a hole-through jack is provided outside the tower column 4. The lower-layer steel strands are connected to the pushing end of the hole-through jack, and both sides exert force simultaneously until the tensile force of the steel strands reaches the preset tensile force. The preset tensile force is generally smaller than the final required design tensile force, usually 20-40% of the design tensile force. At the same time, the steel strands for tensioning in this embodiment are arranged inside the lower cross beam and are not affected by external hazards such as sparks, sundries, and residues, greatly improving the safety.

[0091] Preferably, the preset tensile force is determined by the self-weight of the lower tower column 4, wind load, and the vertical load of the equipment. The vertical load of the equipment is the load generated by the equipment used for construction in the vertical direction. Generally, the self-weight of the climbing formwork and the moment generated by the load borne by the corbel 41 on the root of the tower column 4

[0092] The calculation formula for the preset tensile force is:

[0093]

[0094] where ∑M 风 is the moment generated by the wind load on the root of the tower column 4, ∑M 塔柱 is the moment generated by the self-weight of the tower column 4 on the root of the tower column 4, and ∑M 设备 is the moment generated by the construction equipment on the root of the tower column 4. And H is the height of the lower-layer steel strands from the ground.

[0095] When performing step A33 to pour the concrete of the first height to form the load-bearing layer 1, a preferred embodiment includes the following steps:

[0096] A331. Reserve the first post-cast strip 2 at the mid-span of the load-bearing layer 1. Specifically, in the Figure 1 shown embodiment, the width of the first post-cast strip 2 is 2.5 m.

[0097] A332. Erect the first end formwork at both ends of the first post-cast strip 2, and pour the concrete between the lower side formwork, the first end formwork, and the lower-layer corrugated pipe.

[0098] A333. After the concrete reaches the design strength, remove the first end formwork and clean the end faces at both ends of the first post-cast strip 2. Specifically, when cleaning the end faces of the first post-cast strip 2, it is necessary to increase the adhesion force of the ends by means of chiseling and cleaning.

[0099] A334. Pour the slightly expanding concrete at the first post-cast strip 2 to form the load-bearing layer 1.

[0100] Specifically, the slightly expanding concrete is early-strength and shrinkage-compensating concrete, which combines with the post-cast strip to avoid the problem of cracking of the lower cross beam.

[0101] In order to avoid deformation of the tower column 4 caused by the increased load during the secondary pouring, in some preferred embodiments, the step A5 further includes the following steps:

[0102] A51. Tension the lower steel strands to the designed tension. Specifically, the value of the designed tension is generally provided by the construction requirements. Compared with the preset tension, the designed tension also takes into account the bending moment of the lower cross beam and subsequent bridge structure on the root of tower column 4.

[0103] A52. Clean the top surface of the load-bearing layer 1, and install the upper corrugated pipe on the top surface of the load-bearing layer 1, and pass the upper steel strands in the upper corrugated pipe. Specifically, cleaning the top surface of the load-bearing layer 1 generally needs to wait until the load-bearing layer 1 reaches a certain strength before starting. The purpose of cleaning the top surface of the load-bearing layer 1 is, on the one hand, to remove the debris on the top surface of the load-bearing layer 1 to prevent interference with subsequent pouring, and on the other hand, to make certain improvements to the top surface of the load-bearing layer 1 to increase the adhesion between the concrete and the load-bearing layer 1 during the second pouring. This embodiment cleans the top surface of the load-bearing layer 1 by roughening.

[0104] In addition, a through-hole jack is arranged at the position corresponding to the upper steel strand, and the upper steel strand is connected to the corresponding top push end of the through-hole jack. After the installation is completed, the upper steel strand is only kept in a taut state without being tensioned. The steel strand used for tensioning in this embodiment is arranged inside the lower crossbeam, and will not be affected by external sparks, debris, residues and other harmful objects, and the safety is greatly improved.

[0105] A53. Set up a high side form on the top surface of the low side form, and pour concrete between the high side form and the upper corrugated pipe to the designed height of the lower beam. Specifically, in the case of a harsh construction environment, it can also be poured in multiple layers, but the top surface of the formed part needs to be cleaned and roughened each time it is poured.

[0106] A54. Tension the upper steel strands to the designed tension force, and inject grout into the upper and lower corrugated pipes. Specifically, the corrugated pipes are usually injected with grout into the holes reserved at the anchor pad.

[0107] A55. Pour anchor concrete to form the lower beam.

[0108] In order to prevent cracking during the second pouring, in some preferred embodiments, step A53 also includes the following steps:

[0109] A531. A second post-casting strip 3 is reserved in the middle of the lower cross beam. Specifically, in this embodiment, the width of the second post-casting strip 3 is equivalent to the width of the first post-casting strip 2.

[0110] A532. Set mid-span end formwork at both ends of the second post-casting strip 3.

[0111] Pour concrete between the high-side formwork, the mid-span end formwork and the upper corrugated pipe to the designed height of the lower cross beam.

[0112] A534. After the concrete reaches the designed strength, remove the mid-span end formwork and clean the end of the second post-cast strip 3. Specifically, when cleaning the end of the second post-cast strip 3, not only the fragile parts that have not coagulated well at the end need to be removed, but also the second post-cast strip 3 needs to be roughened and cleaned to increase the adhesion of the end to the slightly expanded concrete.

[0113] A535. Pour slightly expanded concrete at the second post-cast strip 3.

[0114] In some preferred embodiments, in order to reduce the quantity and weight of the construction structure, before constructing the lower cross beam, the following steps are also carried out:

[0115] Pour the joint column 42 on the top surface of the tower column 4, and reserve holes for passing prestressed steel strands in the joint column 42. Specifically, refer to Figure 3 , the size of the joint column 42 is designed according to the shape of the lower cross beam. Generally, it forms a part of the lower cross beam after construction. In the embodiment shown in Figure 1 , the joint column 42 is the end of the load-bearing layer 1. Pouring the joint column 42 in advance can reduce the steel structures used for construction and load-bearing, and reduce the construction cost.

[0116] This application is not limited to the above embodiments. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches are also regarded as within the protection scope of the present invention.

[0117] In the description of this application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation to this application. Unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

[0118] It should be noted that in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0119] The above are only specific embodiments of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A temperature equivalent simulation method is applied to the construction of the lower crossbeam of the bridge main tower. The lower crossbeam is poured in two times. The first pouring forms a load-bearing layer (1) with a first height, and the second pouring reaches the designed height of the lower crossbeam. It is characterized in that: It includes the following steps: S1. Preset the model of the lower crossbeam support (5) according to the construction requirements, and preset the first height. S2. After pouring the load-bearing layer (1) with the first height, calculate the first axial pressure received by each steel pipe column (52) in the lower crossbeam support (5) respectively. S3. Change the temperature of each steel pipe column (52) in the lower crossbeam support (5) until the pressure received at the top of each steel pipe column (52) is equal to the calculated first axial pressure. S4. Calculate whether the load-bearing capacity of the load-bearing layer (1) is the same as the load when the concrete is continuously poured to the designed height of the lower crossbeam. If not, adjust the first height and repeat steps S2 - S3 until the load-bearing capacity is the same as the load. S5. Reduce the first temperature variable of all steel pipe columns (52) in the lower crossbeam support (5), and calculate whether the load-bearing layer (1) can bear the load. If not, increase the first height and recalculate until the load-bearing layer (1) can bear the load; the first temperature variable is the difference between the historical highest temperature and the average temperature at the construction site.

2. A temperature equivalent simulation method according to claim 1, It is characterized in that: In the step S4, adjusting the first height includes the following steps: When the load-bearing capacity of the load-bearing layer (1) is greater than the load, reduce the first height; When the load-bearing capacity of the load-bearing layer (1) is less than the load, increase the first height.

3. A construction method for the lower crossbeam is applied to the lower crossbeam of the bridge main tower. It is characterized in that: It includes the following steps: Determine the first height by using the temperature equivalent simulation method as described in claim 1; Install brackets (41) on the opposite sides of a pair of tower columns (4) of the bridge, and at the same time install the lower crossbeam support (5) on the bridge abutment (6). The two ends of the top of the lower crossbeam support (5) are respectively lapped on the two brackets (41); Carry out the first pouring on the lower crossbeam support (5) to form a load-bearing layer (1) with a first height; After the load-bearing layer (1) is formed, separate the brackets (41) and the lower crossbeam support (5); Carry out the second pouring on the top surface of the load-bearing layer (1) to the designed height of the lower crossbeam to form the lower crossbeam.

4. A construction method for the lower crossbeam according to claim 3, It is characterized in that: When carrying out the first pouring, it includes the following steps: Install the lower corrugated pipe on the top of the lower crossbeam support (5); Thread the lower steel strand into the lower corrugated pipe and tension the lower steel strand to the preset tensile force; Set up the lower side formwork on both sides of the lower crossbeam support (5), and pour the concrete with the first height between the lower corrugated pipe and the lower side formwork to form the load-bearing layer (1).

5. A construction method for the lower crossbeam according to claim 4, It is characterized in that: Pouring the concrete with the first height outside the lower corrugated pipe to form the load-bearing layer (1) includes the following steps: Reserve the first post-cast strip (2) at the mid-span of the load-bearing layer (1); Set up the first end formwork at both ends of the first post-cast strip (2), and pour concrete between the lower side formwork, the first end formwork and the lower layer corrugated pipe; After the concrete reaches the design strength, remove the first end formwork and clean the end faces at both ends of the first post-cast strip (2); Pour slightly expanding concrete at the first post-cast strip (2) to form the load-bearing layer (1).

6. A construction method of a lower cross beam according to claim 4, characterized in that, when performing the second pouring, it includes the following steps: Tension the lower layer steel strands to the design tensile force; Clean the top surface of the load-bearing layer (1), install the upper layer corrugated pipe on the top surface of the load-bearing layer (1), and thread the upper layer steel strands through the upper layer corrugated pipe; Erect the upper side formwork on the top surface of the lower side formwork, and pour concrete between the upper side formwork and the upper layer corrugated pipe to the design height of the lower cross beam; Tension the upper layer steel strands to the design tensile force, and grout in the upper layer corrugated pipe and the lower layer corrugated pipe; Pour the anchor sealing concrete to form the lower cross beam.

7. A construction method of a lower cross beam according to claim 6, characterized in that, pouring concrete between the upper side formwork and the upper layer corrugated pipe to the design height of the lower cross beam includes the following steps: Reserve a second post-cast strip (3) at the mid-span of the lower cross beam; Set up mid-span end formworks at both ends of the second post-cast strip (3); Pour concrete between the upper side formwork, the mid-span end formworks and the upper layer corrugated pipe to the design height of the lower cross beam; After the concrete reaches the design strength, remove the mid-span end formworks and clean the ends of the second post-cast strip (3); Pour slightly expanding concrete at the second post-cast strip (3).

8. A construction method of a lower cross beam according to claim 4, characterized in that: The preset tensile force is determined by the self-weight of the lower tower column (4), the wind load and the vertical load of the equipment.

9. A construction method of a lower cross beam according to claim 3, characterized in that, it further includes the following steps: Pour the joint column (42) on the top surface of the tower column (4), and reserve holes for threading the prestressed steel strands in the joint column (42).

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