阅读说明：本技术 单箱多室直腹板槽型梁横框的内力计算方法 (Internal force calculation method for transverse frame of single-box multi-chamber straight web channel beam ) 是由 曾珍 徐世桥 姚振亚 孙旻 韦福禄 周述美 于 2020-11-23 设计创作，主要内容包括：本发明涉及一种单箱多室直腹板槽型梁横框的内力计算方法,包括如下步骤：建立单箱多室直腹板槽型梁横框的横框模型,该横框模型包括中箱室以及位于该中箱室两侧的边箱室；获取边箱室直腹板底施加弹簧约束的情况下的各该边箱室直腹板的弹簧刚度比；将该边箱室直腹板以及中箱室直腹板的总弹簧刚度值按该弹簧刚度比进行分配并得到该边箱室直腹板底的弹簧刚度值；于该横框模型中输入横框计算荷载,并在该边箱室直腹板底按照相应该弹簧刚度值施加弹簧约束,获取该横框模型的内力。本发明的内力计算方法是一种偏安全的简化方法,更符合结构实际受力情况。根据该内力计算方法求得的内力对该槽型梁横框的顶板和底板进行配筋,优化了钢筋布置。(The invention relates to a method for calculating the internal force of a single-box multi-chamber straight web channel beam transverse frame, which comprises the following steps: establishing a transverse frame model of a transverse frame of the single-box multi-chamber straight web channel beam, wherein the transverse frame model comprises a middle box chamber and side box chambers positioned on two sides of the middle box chamber; acquiring the spring stiffness ratio of each side box chamber straight web plate under the condition that the spring constraint is applied to the side box chamber straight web plate bottom; distributing the total spring stiffness values of the side box chamber straight web plate and the middle box chamber straight web plate according to the spring stiffness ratio and obtaining the spring stiffness value of the side box chamber straight web plate bottom; inputting the calculated load of the transverse frame into the transverse frame model, and applying spring restraint on the bottom of the straight web plate of the side box chamber according to the spring stiffness value required by photographing to obtain the internal force of the transverse frame model. The internal force calculation method is a safer simplified method and better conforms to the actual stress condition of the structure. And reinforcing the top plate and the bottom plate of the transverse frame of the channel beam according to the internal force obtained by the internal force calculation method, so that the arrangement of the reinforcing steel bars is optimized.)

1. A method for calculating the internal force of a transverse frame of a single-box multi-chamber straight web channel beam is characterized by comprising the following steps:

establishing a transverse frame model of a transverse frame of a single-box multi-chamber straight web channel beam, wherein the transverse frame model comprises a middle box chamber and side box chambers positioned on two sides of the middle box chamber;

acquiring the spring stiffness ratio of each side box chamber straight web under the condition that only the side box chamber straight web bottom at the side box chamber position is subjected to spring constraint;

distributing the total spring stiffness values of the side box chamber straight web plate and the middle box chamber straight web plate at the position of the middle box chamber according to the spring stiffness ratio to obtain the spring stiffness value of the bottom of the side box chamber straight web plate;

inputting a transverse frame calculation load into the transverse frame model, and applying spring restraint on the bottom of the straight web plate of the side box chamber according to the corresponding spring stiffness value to obtain the internal force of the transverse frame model.

2. The method for calculating the internal force of a cross frame of a single-tank multi-chamber straight web channel beam according to claim 1, wherein the total spring stiffness value is obtained by:

establishing a longitudinal calculation model of the single-box multi-chamber straight web groove beam transverse frame;

and applying unit force to the mid-span position in the longitudinal calculation model to obtain the total spring stiffness value.

3. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 2, wherein: and establishing the longitudinal calculation model by adopting BSAS software.

4. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 1, wherein: and establishing the transverse frame model by adopting MIDAS Civil software.

5. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 1, wherein:

the single-box multi-chamber straight web groove beam transverse frame is a railway beam transverse frame;

the calculated load of the transverse frame comprises the self weight of the structure, the shrinkage and creep of concrete, the second-stage dead load of a bridge deck system, the live load of a train, a power coefficient and a temperature load.

6. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 1, wherein: and after the internal force of the transverse frame model is obtained, reinforcing the bottom plate and the top plate in the transverse frame model according to the internal force.

7. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 6, wherein: when the reinforcement is distributed on the bottom plate and the top plate in the transverse frame model, the reinforcement is distributed according to the internal force under the working conditions of maximum bending moment, minimum bending moment, maximum axial force and minimum axial force in the transverse frame model.

8. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 7, wherein:

when the internal force of the transverse frame model is obtained, dividing the transverse frame model into a plurality of units, and respectively obtaining the internal force of the units;

and when reinforcing the bottom plate and the top plate in the transverse frame model according to the internal force, reinforcing the bottom plate and the top plate of the corresponding unit according to the internal force of each unit.

9. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in any one of claims 1 to 8, wherein: when a transverse frame model of a single-box multi-chamber straight web channel beam transverse frame is established, segmenting along the length direction of the single-box multi-chamber straight web channel beam transverse frame to form a multi-section structural section, and selecting the multi-section structural section from the multi-section structural section to respectively establish the transverse frame model.

10. The method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam as claimed in claim 9, wherein: the multi-section structural section at least comprises the structural sections at the midspan position and the two quarter positions of the single-box multi-chamber straight web channel beam transverse frame.

Technical Field

The invention relates to the field of urban rail transit, in particular to a method for calculating internal force of a transverse frame of a single-box multi-chamber straight web channel beam.

Background

The channel beam is a type of bridge proposed to reduce the height from the rail surface to the bottom of the beam, thereby increasing the under-bridge clearance. Compared with the traditional overhead bridge, the application of the channel beam to rail transit has the following advantages: the building height is low; the structure is light and beautiful; the web can be used as a sound insulation screen; when the train passes through the groove, the transverse windward side is small.

For the internal force calculation of the transverse frame of the single-box multi-chamber straight web channel beam, the traditional method is to simulate the spring constraint on the position of each straight web, and the spring stiffness ratio of each straight web is calculated reversely by obtaining the deflection ratio of each straight web position through a plate unit model. However, it is known from practical facts that the rigidity of the middle box chamber of the channel beam is greatly different from that of the side box chambers, if all the straight webs are restrained by springs, the middle box chamber is easy to bend and deform, the simulated internal force is larger than the actual internal force, and the reinforcement is arranged according to the simulated internal force, so that great waste is caused.

Disclosure of Invention

The invention provides an internal force calculation method for a single-box multi-chamber straight web channel beam transverse frame, which solves the problems that the calculation result and the actual result are large in difference and large waste is easily caused during reinforcement arrangement.

The invention is realized by the following scheme: a method for calculating the internal force of a transverse frame of a single-box multi-chamber straight web channel beam comprises the following steps:

establishing a transverse frame model of a transverse frame of a single-box multi-chamber straight web channel beam, wherein the transverse frame model comprises a middle box chamber and side box chambers positioned on two sides of the middle box chamber;

acquiring the spring stiffness ratio of each side box chamber straight web under the condition that only the side box chamber straight web bottom at the side box chamber position is subjected to spring constraint;

distributing the total spring stiffness values of the side box chamber straight web plate and the middle box chamber straight web plate at the position of the middle box chamber according to the spring stiffness ratio to obtain the spring stiffness value of the bottom of the side box chamber straight web plate;

inputting a transverse frame calculation load into the transverse frame model, and applying spring restraint on the bottom of the straight web plate of the side box chamber according to the corresponding spring stiffness value to obtain the internal force of the transverse frame model.

The internal force calculation method considers the influence of the integral rigidity of the channel beam larger than the transverse frame rod system model factor, only utilizes the side box chamber straight web plate to bear the total spring rigidity value when distributing the spring rigidity, is a safe simplification method, better accords with the actual stress condition of the structure, is convenient for designers to understand, has high cost performance, strong generalization performance, can reduce the workload of the design process, has reference value for the single-box multi-chamber straight web plate channel beam transverse frame structure, and provides a safe and effective design idea. In addition, the top plate and the bottom plate of the transverse frame of the channel beam are reinforced according to the internal force obtained by the internal force calculation method, so that the reinforcing difficulty is reduced, the reinforcing bar arrangement is optimized, the reinforcing bar utilization efficiency is improved, the safety is high, and the economical efficiency is good.

The invention further improves the method for calculating the internal force of the transverse frame of the single-box multi-chamber straight web channel beam, wherein the total spring stiffness value is obtained by the following method:

establishing a longitudinal calculation model of the single-box multi-chamber straight web groove beam transverse frame;

and applying unit force to the mid-span position in the longitudinal calculation model to obtain the total spring stiffness value.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web groove beam transverse frame, and the longitudinal calculation model is established by adopting BSAS software.

The invention further improves the internal force calculation method of the transverse frame of the single-box multi-chamber straight web channel beam, which adopts MIDAS Civil software to establish the transverse frame model.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web channel beam transverse frame. The load calculation of the transverse frame comprises the self weight of the structure, the shrinkage and creep of concrete, the second-stage constant load of a bridge deck system, the live load of a train, a power coefficient and a temperature load.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web channel beam transverse frame, which is characterized in that after the internal force of the transverse frame model is obtained, the bottom plate and the top plate in the transverse frame model are reinforced according to the internal force.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web channel beam transverse frame, when reinforcing the bottom plate and the top plate in the transverse frame model, reinforcing the ribs according to the internal forces under the working conditions of maximum bending moment, minimum bending moment, maximum axial force and minimum axial force in the transverse frame model.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web channel beam transverse frame, which is characterized in that when the internal force of the transverse frame model is obtained, the transverse frame model is divided into a plurality of units, and the internal forces of the units are respectively obtained. And when reinforcing the bottom plate and the top plate in the transverse frame model according to the internal force, reinforcing the bottom plate and the top plate of the corresponding unit according to the internal force of each unit.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web channel beam transverse frame, when a transverse frame model of the single-box multi-chamber straight web channel beam transverse frame is established, segmentation is carried out along the length direction of the single-box multi-chamber straight web channel beam transverse frame to form a multi-section structural section, and the multi-section structural section is selected from the multi-section structural section to respectively establish the transverse frame model.

The invention further improves the internal force calculation method of the single-box multi-chamber straight web channel beam transverse frame, wherein the multi-section structural sections at least comprise the structural sections at the midspan position and two quarter positions of the single-box multi-chamber straight web channel beam transverse frame.

Drawings

Fig. 1 shows a vertical computational model elevation built using BSAS software.

Fig. 2 shows a cross-frame model elevation built using MIDAS Civil software.

FIG. 3 shows a three-dimensional effect diagram of a transverse frame model established by MIDAS Civil software.

Fig. 4 is a diagram showing a comparison of a reinforcement arrangement based on the internal force calculation method of the present invention with a conventional reinforcement arrangement.

Fig. 5 shows a three-dimensional effect diagram of arrangement of reinforcing bars based on the internal force calculation method of the present invention.

Detailed Description

Because the traditional internal force calculation method of the transverse frame of the single-box multi-chamber straight web groove beam is generally used for simulating spring constraint on the position of each straight web, the combination of practice shows that the rigidity of a middle box chamber of the groove beam is greatly different from that of side box chambers, if spring constraint is applied to all the straight webs, the middle box chamber is easily bent and deformed, the simulated internal force is larger than the actual internal force, and great waste is caused if rib arrangement is carried out according to the simulated internal force. In order to solve the problems, the invention provides a novel internal force calculation method of a single-box multi-chamber straight web channel beam transverse frame by combining with the demonstration of a solid model on the premise of ensuring the structural safety.

The following takes a single-box five-chamber straight web channel beam cross frame as an example, and the method for calculating the internal force of the single-box multi-chamber straight web channel beam cross frame is further explained by combining the accompanying drawings.

Referring to fig. 1 to 3, fig. 1 shows an elevation view of a longitudinal calculation model established by using BSAS software; FIG. 2 shows a cross-frame model elevation built using MIDAS Civil software; FIG. 3 shows a three-dimensional effect diagram of a transverse frame model established by MIDAS Civil software.

The single-box five-chamber straight web channel beam transverse frame in the embodiment comprises a top plate 1, a bottom plate 2 and six straight webs fixed between the top plate 1 and the bottom plate 2 at intervals, wherein the six straight webs divide the channel beam transverse frame into five boxes, namely three middle boxes A in the middle and two side boxes B on two opposite sides of the three middle boxes A, due to the structural characteristics of the single-box multi-chamber straight web channel beam transverse frame, the four straight webs on the positions of the two side boxes B are higher, the two straight webs on the positions of the three middle boxes A are lower, the four straight webs on the positions of the two side boxes B are represented as side box straight webs 3, and the two straight webs on the positions of the three middle boxes A are represented as middle box straight webs 4.

A method for calculating the internal force of a transverse frame of a single-box multi-chamber straight web channel beam comprises the following steps:

step 1, establishing a transverse frame model of a single-box multi-chamber straight web channel beam transverse frame, wherein the transverse frame model comprises three middle box chambers A and two side box chambers B positioned at two sides of the middle box chambers.

Specifically, the present embodiment uses the MIDAS Civil software commonly used in bridge computing to establish the horizontal frame model.

And 2, acquiring the spring stiffness ratio of each side box chamber straight web 3 under the condition that the spring is restrained only at the bottom of the side box chamber straight web 3 at the position of the side box chamber B.

Specifically, the spring rate ratio is related to the structure of each side chamber straight web 3 itself, and in the present embodiment, the four side chamber straight webs 3 have the same structure, so the spring rate ratio is 1:1:1: 1.

And 3, distributing the total spring stiffness values of the side box chamber straight web plate 3 and the middle box chamber straight web plate 4 positioned at the middle box chamber A position according to the spring stiffness ratio and obtaining the spring stiffness value of the bottom of the side box chamber straight web plate 3.

And 4, inputting a transverse frame calculation load into the transverse frame model, and applying spring restraint at the bottom of the straight web plate 3 of the side box chamber according to the corresponding spring stiffness value to obtain the internal force of the transverse frame model.

Specifically, each parameter of the calculated load of the transverse frame is input into the transverse frame model, and the specific spring stiffness value of each side box chamber straight web 3 is input into the transverse frame model, so that the internal force (including bending moment and axial force) of the transverse frame model in any region under any working condition can be obtained through the transverse frame model. As for the specific structure and principle of the horizontal frame model, which belong to the prior art, the detailed description will be omitted.

The invention considers that the rigidity of the middle box chamber A is greatly different from that of the side box chamber B, the middle box chamber A approaches to a component hung on the straight web plate 3 of the side box chamber, so the spring constraint at the bottom of the straight web plate 4 of the middle box chamber is cancelled, and the spring constraint is only applied at the bottom of the straight web plate 3 of the side box chamber. Meanwhile, the influence of the factor that the integral rigidity of the groove-shaped beam is larger than that of the transverse frame rod system model is considered, so that the method only utilizes the side box chamber straight web plate to bear the total spring rigidity value is considered when the spring rigidity is distributed, the method is a safer and simplified method, the actual stress condition of the structure is better met, the method is convenient for designers to understand, the cost performance is high, the popularization is strong, and the workload in the design process can be reduced. The internal force calculation method can be applied to any one-way multi-chamber (more than three chambers) straight web channel beam transverse frame structure.

As a preferred embodiment, the total spring stiffness value is obtained by: establishing a longitudinal calculation model of the single-box multi-chamber straight web groove beam transverse frame; and applying unit force to a mid-span position in the longitudinal calculation model to obtain the total spring stiffness value.

Specifically, the longitudinal calculation model (as shown in fig. 1) is preferably built by using BSAS software, and a unit force is applied to the midspan position, where the unit force may be 1N or 1KN, and of course, other realizable software may be used for the longitudinal calculation model to simulate the longitudinal calculation model.

As a preferred embodiment, the single-box multi-chamber straight web channel beam transverse frame is a railway beam transverse frame. The calculated load of the transverse frame comprises the self weight of the structure, the shrinkage and creep of concrete, the second-stage dead load of a bridge deck system, the live load of a train, a power coefficient and a temperature load.

Specifically, in order to make the calculation load of the horizontal frame more accurate, it is preferable that the live load of the train is a middle live load, and the value of the middle live load needs to be determined by considering the longitudinal and transverse distribution widths, and the temperature load needs to include a sunshine temperature load and a cold tide temperature load. Each parameter of the calculated load of the transverse frame is only the basic parameter of the beam transverse frame for the railway, and the parameters of the calculated load of the beam transverse frame in other application occasions are calculated by referring to the corresponding transverse frame, and are not repeated herein.

Referring to fig. 2, 4 and 5, as a preferred embodiment, fig. 4 is a graph showing a comparison of a reinforcement bar arrangement based on the internal force calculation method of the present invention with a conventional reinforcement bar arrangement; fig. 5 shows a three-dimensional effect diagram of arrangement of reinforcing bars based on the internal force calculation method of the present invention. After the internal force of the horizontal frame model is obtained (i.e., step 4 is performed), the bottom plate 2 and the top plate 1 in the horizontal frame model are reinforced according to the internal force.

Specifically, because the internal force calculation method cancels the spring constraint of the straight web 4 of the middle box chamber, the calculated internal force is smaller than that calculated by the traditional calculation method, and the reinforcing bars according to different internal forces also need to be correspondingly adjusted. For example, in the case of the single-box five-chamber straight web channel beam horizontal frame in the present embodiment, when reinforcing the bottom plate 2 and the top plate 1: if reinforcement is carried out according to the internal force calculated by the traditional calculation method, for a transverse frame template with the length of 1 meter, 10 transverse stressed steel bars 6 'with the diameter of 25mm (such as S' in fig. 4) need to be arranged in the top plate 1 and the bottom plate 2 at intervals; if reinforcement is performed according to the internal force calculated by the calculation method of the present invention, only 10 transverse stressed steel bars with a diameter of about 23.5mm may need to be configured, but due to the limitation of the standard specification of the steel bars, the diameter requirement may not be met, so the present embodiment meets the structural stress requirement, in the present embodiment, 15 transverse stressed steel bars with a diameter of 22mm are selected to be arranged alternately in a single-piece and double-piece manner (i.e., in a manner of being juxtaposed at intervals, such as S in fig. 4), and by adopting this manner, not only the distance of 10cm between the steel bars can be maintained, but also the section area of the reinforcement is larger, so that the structural stress performance is better. The reinforcement scheme is only an optimal scheme, and a reinforcement optimization idea is provided for the condition that the steel bars with the suitable specifications cannot be provided.

In a preferred embodiment, when reinforcing the bottom plate 2 and the top plate 1 in the horizontal frame model, reinforcing bars are arranged according to internal forces (including bending moment and axial force) under the working conditions of maximum bending moment, minimum bending moment, maximum axial force and minimum axial force in the horizontal frame model according to the design specifications of reinforced concrete and prestressed concrete structures of railway bridges and culverts. The internal force under the typical working condition is obtained, a reinforcement distribution scheme is made according to the internal force, the calculated amount is reduced as much as possible on the premise that the calculation accuracy of the internal force is guaranteed, reinforcement distribution is more complete and optimized, a specific reinforcement distribution method is the prior art, and details are not repeated here.

As a preferred embodiment, in order to further make the reinforcement more reasonable and more optimized, when the internal force of the horizontal frame model is obtained, the horizontal frame model is divided into a plurality of units (as shown in fig. 2, each unit may be numbered to avoid confusion of each unit), and the internal forces of the plurality of units are obtained respectively; when the bottom plate 2 and the top plate 1 in the transverse frame model are reinforced according to the internal force, the bottom plate 2 and the top plate 1 of the corresponding unit are respectively reinforced according to the internal force of each unit. It should be noted that, since the positions where the cross-sectional areas of the top plate 1 and the bottom plate 2 change (i.e., the armpit positions 5) and the joints of the side cabinet straight webs 3 and the top plate 1 are large, the positions need to be divided into separate units when dividing the units, and important consideration should be given when performing reinforcement.

In order to improve the accuracy of calculating the internal force of the single-box multi-chamber straight web channel beam cross frame, the present embodiment, when building a cross frame model of the single-box multi-chamber straight web channel beam cross frame, performs segmentation along the length direction of the single-box multi-chamber straight web channel beam cross frame to form a plurality of structural sections, selects a plurality of structural sections among the plurality of structural sections to respectively build the cross frame model, and calculates the internal force for each cross frame model, and of course, when reinforcing the bottom plate 2 and the top plate 1, the internal force of each cross frame model is also used as the basis.

As a preferred embodiment, the multi-section structural section of the present embodiment preferably includes at least the structural sections at the midspan position and two quarter positions of the horizontal frame of the single-box multi-chamber straight web channel beam. The position is a typical position of the whole single-box multi-chamber straight web groove beam, and the calculation amount is reduced as far as possible on the premise of ensuring the accuracy of internal force calculation.

While the present invention has been described in detail and with reference to the embodiments thereof as illustrated in the accompanying drawings, it will be apparent to one skilled in the art that various changes and modifications can be made therein. Therefore, certain details of the embodiments are not to be interpreted as limiting, and the scope of the invention is to be determined by the appended claims.