Calculation method, system and storage medium for the push-out resistance of steel tenons in UHPC ribs

Abstract

The present invention provides a method, system and storage medium for calculating the push-out resistance of a steel tenon in a vertical UHPC rib plate. The method comprises: under the proposed structural dimensions of a composite structural beam, calculating the design value of the horizontal shear effect of the steel tenon and the push-out resistance of the steel tenon in the UHPC rib plate. If and satisfy the judgment condition, it indicates that the push-out resistance meets the requirement, otherwise the structural dimensions need to be adjusted and recalculated; the method further comprises: calculating the strength factor of the steel tenon and the UHPC rib plate based on the proposed structural dimensions. If the strength factor is less than 4.5, it indicates that the structure is reasonable, otherwise the structural dimensions need to be adjusted and the strength factor needs to be recalculated. The present invention helps engineering and technical personnel to judge the key mechanical properties of composite structural beams.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and in particular to a method, system and storage medium for calculating the push-out resistance of a steel tenon in a UHPC rib plate. Background Art

[0002] With the popularity of ultra-high performance concrete (UHPC), existing bridge technologies in recent years have attempted to use UHPC to replace ordinary concrete (NC) as the main building material to achieve the requirements of reducing deadweight and improving performance, such as steel beam-UHPC bridge deck composite beams, but there are also defects such as the material performance cannot be fully utilized, the amount of steel used and the welding workload are large. In order to make full use of the excellent performance of steel and UHPC materials and further improve the economy and applicability of steel-UHPC composite beams, some new composite beam structures have been proposed. Among the currently disclosed technologies, Chinese patent applications with publication numbers CN112391932A and CN112342889A both propose a UHPC-T-beam using steel as external reinforcement. The idea is to use UHPC to bear the high pressure stress of the upper flange and the low tensile stress of the composite web, and use steel to bear the high tensile stress of the lower part, making full use of the material properties.

[0003] When the composite structural beam is subjected to bending moment, a relative slip tendency will occur between the steel beam and the concrete slab. This slip will generate horizontal shear force at the interface. The horizontal shear resistance (anti-pushout) between steel and concrete in the composite structural beam is a key factor in the overall force of the composite structural beam. The horizontal shear force of the traditional composite structural beam is generally achieved by studs. The stud setting requires a horizontally arranged upper flange of the steel beam and a horizontally arranged bridge deck to meet the requirements of the layout structure. However, the steel tenon of the externally reinforced UHPC-T-beam is set in the vertical UHPC thin rib plate, and its structural form and anti-pushout force transmission mechanism have undergone essential changes. "Research on the Mechanical Properties of MCL-shaped Composite Tenon Connections of New UHPC-Steel Composite Bridges", Yu Chunyi, South China University of Technology, April 26, 2023, pages 12-70 studied the performance of steel tenons in horizontal UHPC slabs and concrete slabs, but did not involve the anti-pushout performance of steel tenons in vertical UHPC thin rib plates. "Study on the Flexural Performance of a New Type of Composite Beam with Self-Contained Steel Pins-UHPFRC", He Yaobei, Shen Xiujiang, Shao Xudong, et al., China Journal of Highway and Transport, Issue 10, 2024, July 12, 2024, pp. 85-97, studied the flexural performance of composite beams with steel dowels in vertical UHPC thin ribs, but did not study the push-out performance. The push-out failure mode and load transfer mechanism of steel dowels in vertical UHPC thin ribs are significantly different from those of steel dowels in horizontal UHPC slabs or concrete slabs. Therefore, if simply applied, the structure may have safety hazards due to insufficient understanding of the failure mode, endangering the safety of life and property.

[0004] Foreign researchers have studied the push-out resistance of steel tenons in thin concrete slabs, but due to the superior mechanical properties of UHPC compared to ordinary concrete, its failure mode and force transmission method have undergone fundamental changes. Ordinary concrete is very easy to be destroyed under the extrusion of steel tenons due to its low strength and easy cracking. The point of action of the combined force of the steel tenon is relatively high, which causes the steel tenon to be often in a composite stress state of bending and shear, affecting the performance of the steel tenon connector. However, due to its high strength and strong crack resistance, UHPC will not be locally crushed under the extrusion of the steel tenon. Therefore, UHPC can strongly support the steel tenon, and the steel tenon will be in a simpler shear state, and the push-out resistance will be greatly improved. If the calculation method of the push-out resistance of steel tenons in vertical concrete thin plates is simply used for thin UHPC ribs, the performance of steel tenon connectors will be greatly underestimated, resulting in waste, which will affect the promotion of externally reinforced UHPC-T-beam structures.

[0005] In summary, there is an urgent need for a method, system and storage medium for calculating the push-out resistance of steel tenons in UHPC ribs to solve the problems existing in the prior art. Summary of the invention

[0006] The purpose of the present invention is to provide a method for calculating the push-out resistance of steel tenons in UHPC ribs, aiming to solve the problem that there is no corresponding method in the prior art to guide the calculation and design of the push-out resistance of steel tenon connectors in composite structural beams of steel and UHPC to ensure the safety and economy of the bridge. The specific technical solution is as follows:

[0007] A method for calculating the push-out resistance of steel tenons in UHPC ribs, comprising:

[0008] S1. Obtain the design value of the vertical shear effect of the composite structural beam under the proposed structural size Design values ​​of the effects of bending moment ;

[0009] S2. Design value based on the geometric parameters of the cross section of the composite structure beam and the effect of vertical shear force Design values ​​of the effects of bending moment , calculate the design value of the horizontal shear effect of the steel tenon ;

[0010] S3. Calculation of the push-out resistance of steel tenons in UHPC ribs ;

[0011] S4, if satisfied , it indicates that the anti-pushout capability meets the requirements, otherwise it is necessary to adjust the structural dimensions and re-enter step S1 for calculation; where, is the importance coefficient of the composite structural beam, is the material partial factor, The spacing of the steel tenons.

[0012] In the above technical solution, preferably, step S2 is as follows:

[0013] S2.1. Convert the cross section of the composite structural beam into a cross section of a single material;

[0014] S2.2. Design value based on the effect of bending moment The distance from the neutral axis NA to the top of the section is obtained iteratively using the section layering method. , and calculate the moment of inertia of the cross section about the neutral axis NA ;

[0015] S2.3. According to the moment of inertia of the cross section about the neutral axis NA and the design value of the effect of vertical shear , calculate the design value of the horizontal shear effect of the steel tenon .

[0016] Preferably, in the above technical solution, in step S2.1, the cross section of the composite structural beam is converted into a cross section of a single material, specifically:

[0017] Multiply the thickness of the UHPC rib plate in the cross section of the composite structure beam and the width of the UHPC bridge deck by , and obtain the cross section of a single material; among them, the elastic modulus ratio , is the elastic modulus of the steel web, is the elastic modulus of UHPC concrete.

[0018] In the above technical solution, the design value of the horizontal shear effect of the steel tenon is calculated in step S2.3. , specifically:

[0019] (1),

[0020] in, S is the static moment of the section below the height of the steel tenon, is the width of the steel tenon in the section.

[0021] In the above technical solution, preferably, in step S3, the anti-pullout capability of the steel tenon in the UHPC rib is calculated. , specifically:

[0022] The composite structural beam has three failure modes under the action of horizontal shear force: steel tenon failure, UHPC rib splitting failure, and UHPC rib shear failure. The horizontal shear bearing capacity characteristic values ​​under the three failure modes are calculated respectively, and the minimum value is selected as the anti-push-out capacity of the steel tenon in the UHPC rib. .

[0023] The preferred technical solution above is that the characteristic value of horizontal shear bearing capacity under the failure mode of the steel tenon is for:

[0024] (2),

[0025] Characteristic value of horizontal shear bearing capacity of UHPC ribbed slab under splitting failure mode for:

[0026] (3),

[0027] Characteristic value of horizontal shear bearing capacity of UHPC ribbed slab under shear failure mode for:

[0028] (4),

[0029] Push-out resistance of steel tenons in UHPC ribs for:

[0030] (5),

[0031] in, is the standard value of axial tensile strength of UHPC concrete, is the thickness of the UHPC rib plate, is the yield strength of the steel web, is the thickness of the steel web, is the arrangement spacing of the steel tenons, is the adjustment factor, is the shear area of ​​UHPC concrete corresponding to a single steel tenon, .

[0032] Preferably, in the above technical solution, the calculation method further comprises: calculating the strength factor of the steel tenon and the UHPC rib plate based on the proposed structural dimensions , if the intensity factor <4.5 indicates that the structure is reasonable, otherwise the strength factor needs to be recalculated after adjusting the structural dimensions. ;

[0033] Among them, the strength factor of steel tenon and UHPC rib is for:

[0034] (6),

[0035] in, is the yield strength of the steel web; is the thickness of the steel web, is the standard value of axial tensile strength of UHPC concrete, is the thickness of the UHPC rib.

[0036] The above technical solution is preferably based on the intensity factor The method for determining the failure mode between the steel tenon and the UHPC rib plate under the current structural size is:

[0037] when When , it indicates that the steel tenon failure occurs between the steel tenon and the UHPC rib plate under the action of horizontal shear force;

[0038] when When , it indicates that the splitting failure of the UHPC rib occurs between the steel tenon and the UHPC rib under the action of horizontal shear force;

[0039] when , it indicates that shear failure of the UHPC rib occurs between the steel tenon and the UHPC rib under the action of horizontal shear force.

[0040] The present invention also provides a system for calculating the anti-pushing ability of steel tenons in UHPC ribs, the system comprising a memory and a processor, and the processor executes the calculation method when running computer instructions stored in the memory.

[0041] The present invention also provides a storage medium, in which computer instructions are stored, and the computer instructions are configured to execute the calculation method when running.

[0042] The application of the technical solution of the present invention has the following beneficial effects:

[0043] The composite structural beam design method proposed in the present invention helps engineering technicians to judge the key mechanical properties of the structure. The calculation method is scientific and efficient, which helps to promote the engineering application of the innovative structure and create social and economic value.

[0044] The method of the present invention can take into account the influence of the change in the stress mechanism after the UHPC rib plate is cracked by bending. Specifically: if the effect design value of the bending moment is The tensile part of UHPC is in the elastic section. The position of the neutral axis NA will not change with the increase of is a fixed value; If the UHPC ribs are further increased, after the UHPC ribs are softened or cracked under tension, according to the section axial force and bending moment equilibrium conditions, the neutral axis NA will move upward, that is, Continuously decreases, resulting in the static moment and inertia moment of the upper and lower parts of the neutral axis NA changes. Due to the neutral axis position It is the design value based on the effect of bending moment The cross-sectional layering method is used to iteratively confirm the The method of the present invention can take into account the effect design value of the bending moment under different stress conditions. Design value of horizontal shear effect of steel dowels The impact produced ensures the safety of the steel tenon design.

[0045] The method of the present invention is through the intensity factor Qualitative analysis of the failure mode between the steel tenon and the UHPC rib plate was performed to determine the anti-pushout capability. Design value of horizontal shear effect of steel dowel Quantitative analysis of the push-out resistance between the steel tenon and the UHPC rib plate can ensure that the failure mode is an ideal ductile failure and that the push-out resistance meets the safety requirements, which can be used to judge the safety level of the composite structural beam.

[0046] The method of the present invention gives the intensity factor The calculation method of intensity factor The method of judging the failure mode and the calculation method of the characteristic value of horizontal shear bearing capacity under various failure modes can well guide designers to design the failure mode of composite structural beams as ideal ductile failure, and guide the improvement of the shear resistance and splitting resistance of UHPC ribs.

[0047] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0049] Figure 1 It is an axonometric view of the composite structural beam of steel and UHPC;

[0050] Figure 2 yes Figure 1 Structural diagram of the middle vertical stirrup group;

[0051] Figure 3 yes Figure 1 Schematic diagram of the structure of the steel tenon and mortise;

[0052] Figure 4 yes Figure 3 Top view of the steel tenon and mortise;

[0053] Figure 5 It is a schematic diagram of the cross section of a composite structural beam;

[0054] Figure 6It is a screenshot diagram of the converted cross section of the composite structural beam;

[0055] Figure 7 It is a flow chart of the method for calculating the push-out resistance of the steel tenon in the UHPC rib plate of the present invention;

[0056] Among them, 100, composite structure beam, 110, UHPC bridge deck, 111, bridge deck transverse reinforcement, 112, bridge deck longitudinal reinforcement, 120, UHPC rib, 121, lower open stirrups, 122, upper open stirrups, 123, the bottom layer of longitudinal reinforcement, 124, the second bottom layer of longitudinal reinforcement, 125, longitudinal distribution reinforcement, 126, transverse short reinforcement, 130, T-shaped steel beam, 131, steel bottom plate, 132, steel web, 133, steel tenon, 134, mortise. DETAILED DESCRIPTION

[0057] In order to facilitate the understanding of the present invention, the present invention will be described more fully below, and preferred embodiments of the present invention are provided. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0059] Embodiment 1:

[0060] Figure 1-Figure 4 A composite structural beam of steel and UHPC is illustrated, the composite structural beam 100 comprises a UHPC bridge deck 110 and a composite rib (not shown) located on the bottom surface of the UHPC bridge deck 110, the composite rib comprises a UHPC rib 120 and a T-shaped steel beam 130, the UHPC rib 120 is located between the UHPC bridge deck 110 and the T-shaped steel beam 130, that is, the UHPC rib 120 and the UHPC bridge deck 110 are cast together to form a T-shaped structure, and the upper edge of the T-shaped steel beam 130 is buried inside the lower end of the UHPC rib 120.

[0061] Furthermore, the T-shaped steel beam 130 includes a steel bottom plate 131 and a steel web 132 disposed on the steel bottom plate 131, the two forming a T-shaped structure, and the upper edge of the steel web 132 (i.e., the side close to the UHPC rib 120) is alternately provided with steel tenons 133 and mortises 134 along the longitudinal bridge direction. Figure 3 As shown, Figure 3The gray area in the figure is the mortise 134, and the distance between two adjacent tenons 133 is , the height of the steel tenon (i.e. the depth of the mortise) is The steel tenon 133 and the mortise 134 are embedded in the concrete at the lower end of the UHPC rib 120, and the distance between the lower edge of the UHPC rib 120 and the bottom edge of the mortise 134 is .

[0062] Furthermore, the UHPC rib 120 includes a rib concrete layer and a rib reinforcement skeleton located in the rib concrete layer, wherein the rib reinforcement skeleton includes a bottom layer of longitudinal reinforcement 123, a second bottom layer of longitudinal reinforcement 124, a longitudinal distribution reinforcement 125, a transverse short reinforcement 126 and a vertical stirrup group (not shown in the figure); the vertical stirrup group includes lower open stirrups 121 and upper open stirrups 122 alternately arranged along the longitudinal bridge direction, such as Figure 1 and Figure 2 As shown, the lower open stirrup 121 and the steel tenon 133 are arranged in a one-to-one correspondence, the upper open stirrup 122 and the mortise 134 are arranged in a one-to-one correspondence, the steel tenon 133 is inserted into the opening at the lower end of the lower open stirrup 121, the lower end of the upper open stirrup 122 is placed in the mortise 134, and transverse short steel bars 126 are provided on both sides of the lower end of the upper open stirrup 122, and the transverse short steel bars 126 are spaced from the lower end of the upper open stirrup 122 (that is, the two are not overlapped); the position of the lower end of the lower open stirrup 121 is lower than that of the upper open stirrup 122 At the lower end, the bottom layer of longitudinal steel bars 123 is used to connect the lower ends of the lower open stirrups 121 along the longitudinal direction, and the second bottom layer of longitudinal steel bars 124 is used to connect the lower ends of the upper open stirrups 122 along the longitudinal direction. Specifically, in this embodiment, the number of the bottom layer of longitudinal steel bars 123 and the second bottom layer of longitudinal steel bars 124 are both two, and they are symmetrically arranged on both sides of the steel web 132; a plurality of longitudinal distribution steel bars 125 are arranged inside the vertical stirrup group along the vertical direction, and specifically, a single longitudinal distribution steel bar 125 passes through the alternately arranged upper open stirrups 122 and lower open stirrups 121 along the longitudinal direction.

[0063] Furthermore, the UHPC bridge deck 110 includes a bridge deck concrete layer and a bridge deck steel bar skeleton located in the bridge deck concrete layer, the bridge deck steel bar skeleton includes an upper transverse steel bar group, a lower transverse steel bar group and a bridge deck longitudinal steel bar 112; a plurality of bridge deck longitudinal steel bars 112 are arranged at intervals along the transverse direction of the bridge, the upper transverse steel bar group is located on the upper side of the bridge deck longitudinal steel bars 112, the upper transverse steel bar group includes a plurality of bridge deck transverse steel bars 111 arranged at intervals along the longitudinal direction of the bridge, the bridge deck longitudinal steel bars 112 are overlapped with the bridge deck transverse steel bars 111 in the upper transverse steel bar group; the lower transverse steel bar group is located on the lower side of the bridge deck longitudinal steel bars 112, the lower transverse steel bar group includes a plurality of bridge deck transverse steel bars 111 arranged at intervals along the longitudinal direction of the bridge, and the bridge deck transverse steel bars 111 in the lower transverse steel bar group are not overlapped with the bridge deck longitudinal steel bars 112.

[0064] Furthermore, the upper end of the lower open stirrup 121 is connected to the bridge deck reinforcement skeleton, specifically, overlapped with the bridge deck longitudinal reinforcement 112 .

[0065] Preferably, the bridge deck concrete layer and the rib concrete layer are both cast using UHPC concrete, and the UHPC concrete is an ultra-high performance concrete having ultra-high durability and ultra-high mechanical properties.

[0066] Furthermore, the lower end of the UHPC rib 120 is thickened at the buried steel tenon 133 and the mortise 134 (i.e., a reinforced horseshoe is provided) to ensure that the transverse distance from the steel tenon to the edge of the UHPC rib 120 is not less than 5 times the height of the steel tenon, thereby improving the tolerance of the centering error between the steel web 132 and the UHPC rib 120, and at the same time providing bending space for the upper open stirrups and the lower open stirrups and reserving sufficient protective layer thickness for the stirrups, thereby improving the bonding ability between the steel web and the UHPC rib 120.

[0067] In order to ensure the safe application of UHPC and steel composite structural beams, this embodiment provides a method for calculating the push-out resistance of steel tenons in UHPC ribs, such as Figure 3-Figure 7 As shown, the calculation method includes the following steps:

[0068] S1. Obtain the design value of the vertical shear effect of the composite structural beam under the proposed structural size Design values ​​of the effects of bending moment ;

[0069] Specifically, the permanent action of the composite structural beam is determined according to the structural dimensions of the proposed composite structural beam, and the variable action is determined according to the use requirements and environmental conditions of the composite structural beam; then, the effect design value of the vertical shear force under the basic combination of action effects is obtained based on the effect design value of the permanent action and the effect design value of the variable action. Design values ​​of the effects of bending moment .

[0070] Among them, the determination method of permanent action and variable action can be referred to the prior art, and no further detailed description is given in this embodiment. Preferably, the effect design value of the composite structure beam under permanent action and the effect design value under variable action are determined according to the general bridge internal force calculation method, and the effect design value of the permanent action and the effect design value of the variable action in the "General Specification for Design of Highway Bridges and Culverts" (JTG D60-2015) are combined to obtain the effect design value of the basic combination of action effects.

[0071] S2. Design value based on the geometric parameters of the cross section of the composite structure beam and the effect of vertical shear force Design values ​​of the effects of bending moment , calculate the design value of the horizontal shear effect of the steel tenon ;

[0072] Preferably, step S2 in this embodiment is specifically as follows:

[0073] S2.1. Convert the cross section of the composite structural beam into a cross section of a single material, specifically:

[0074] Multiply the thickness of the UHPC rib plate in the cross section of the composite structure beam and the width of the UHPC bridge deck by , and obtain the cross section of a single material (i.e., steel web material), such as Figure 5 and Figure 6 As shown; Among them, the elastic modulus ratio , is the elastic modulus of the steel web, is the elastic modulus of UHPC concrete.

[0075] S2.2. Design value based on the effect of bending moment The distance from the neutral axis NA to the top of the section is obtained iteratively using the section layering method. , and calculate the moment of inertia of the cross section about the neutral axis NA ;

[0076] Preferably, in step S2.2, the design value is based on the effect of the bending moment. The cross-section layering method is used to iteratively calculate the distance from the neutral axis NA of the overall cross-section to the top of the overall cross-section according to the cross-section axial force and bending moment equilibrium conditions. For the specific iterative method, please refer to the prior art, which will not be described in detail in this embodiment. For example, Chinese patent application with publication number CN118965548A discloses a design method for a composite structural beam of steel and UHPC, wherein paragraphs 0039 to 0054 disclose the method of determining the composite structural beam by iterative calculation. method.

[0077] Furthermore, the moment of inertia of the cross section about the neutral axis NA is For the calculation method of , please refer to the prior art and will not be described in detail in this embodiment.

[0078] S2.3. According to the moment of inertia of the cross section about the neutral axis NA and the design value of the effect of vertical shear , calculate the design value of the horizontal shear effect of the steel tenon , specifically:

[0079] (1),

[0080] in, S is the static moment of the section below the height of the steel tenon, is the width of the steel tenon in the section.

[0081] S3. Calculation of the push-out resistance of steel tenons in UHPC ribs ;

[0082] Specifically, the composite structural beam has three failure modes under the action of horizontal shear force: steel tenon failure, UHPC rib splitting failure, and UHPC rib shear failure. The horizontal shear bearing capacity characteristic values ​​under the three failure modes are calculated respectively, and the minimum value is selected as the push-out resistance of the steel tenon in the UHPC rib. .

[0083] Preferably, the horizontal shear bearing capacity characteristic value under the steel tenon failure mode in this embodiment is for:

[0084] (2),

[0085] Characteristic value of horizontal shear bearing capacity of UHPC ribbed slab under splitting failure mode for:

[0086] (3),

[0087] Characteristic value of horizontal shear bearing capacity of UHPC ribbed slab under shear failure mode for:

[0088] (4),

[0089] Push-out resistance of steel tenons in UHPC ribs for:

[0090] (5),

[0091] in, is the standard value of axial tensile strength of UHPC concrete, is the thickness of the UHPC rib plate, is the yield strength of the steel web, is the thickness of the steel web, is the arrangement spacing of the steel tenons, is the adjustment coefficient (generally 2.3), is the shear area of ​​the UHPC concrete corresponding to a single steel tenon (the area of ​​the horizontal section of the UHPC rib concrete minus the area of ​​the horizontal section of part of the steel web, such as Figure 4 ), ;in, and All are actual values ​​in the structural dimensions, that is, the values ​​before conversion.

[0092] S4, if satisfied , it indicates that the anti-pushout capability meets the requirements, otherwise it is necessary to adjust the structural dimensions and re-enter step S1 for calculation; where, is the importance coefficient of the composite structure beam, which is 0.9, 1.0, and 1.1 according to the importance of the bridge; is the material partial factor, which is used to convert the calculated bearing capacity characteristic value into the corresponding bearing capacity design value and is taken as 1.25.

[0093] Furthermore, the calculation method also includes: calculating the strength factor of the steel tenon and the UHPC rib plate based on the proposed structural dimensions , if the intensity factor <4.5 indicates that the structure is reasonable, otherwise the strength factor needs to be recalculated after adjusting the structural dimensions. ;

[0094] Among them, the strength factor of steel tenon and UHPC rib is for:

[0095] (6),

[0096] in, is the yield strength of the steel web; is the thickness of the steel web, is the standard value of axial tensile strength of UHPC concrete, is the thickness of the UHPC rib.

[0097] when When , it indicates that the steel tenon failure occurs between the steel tenon and the UHPC rib plate under the action of horizontal shear force;

[0098] when When , it indicates that the splitting failure of the UHPC rib occurs between the steel tenon and the UHPC rib under the action of horizontal shear force;

[0099] when When , it indicates that shear failure of the UHPC rib occurs between the steel tenon and the UHPC rib under the action of horizontal shear force;

[0100] Furthermore, the failure of the steel tenon is an ideal ductile failure, while the shear failure and splitting failure of the UHPC rib are typical brittle failures. In practice, designers should avoid the shear failure and splitting failure of the UHPC rib according to their judgment requirements and try to avoid the failure of the steel tenon.

[0101] The method of this embodiment can take into account the influence of the change in the stress mechanism after the UHPC rib plate is cracked by bending. Specifically: if the effect design value of the bending moment The tensile part of UHPC is in the elastic section. The position of the neutral axis NA will not change with the increase of is a fixed value; If the UHPC ribs are further increased, after the UHPC ribs are softened or cracked under tension, according to the section axial force and bending moment equilibrium conditions, the neutral axis NA will move upward, that is, The static moment and inertia moment of the upper and lower parts of the neutral axis NA change continuously. It is the design value based on the effect of bending moment The cross-sectional layering method is used to iteratively confirm the The method of this embodiment can take into account the effect design value of the bending moment under different stress conditions. Design value of horizontal shear effect of steel dowels The impact produced ensures the safety of the steel tenon design.

[0102] In addition, the method of this embodiment uses the intensity factor Qualitative analysis of the failure mode between the steel tenon and the UHPC rib plate was performed to determine the anti-pushout capability. Design value of horizontal shear effect of steel dowel Quantitative analysis of the push-out resistance between the steel tenon and the UHPC rib plate can ensure that the failure mode is an ideal ductile failure and that the push-out resistance meets the safety requirements, which can be used to judge the safety level of the composite structural beam.

[0103] The method of this embodiment gives the intensity factor The calculation method of intensity factor The method of judging the failure mode and the calculation method of the characteristic value of horizontal shear bearing capacity under various failure modes can well guide the designers to design the failure mode of the composite structure beam as an ideal ductile failure, and guide the improvement of the shear resistance and splitting resistance of the UHPC ribs. For example: 1) In order to further improve the shear resistance of the UHPC ribs, reinforcing horseshoes can be set in a certain range near the steel tenon to reduce value; 2) In order to improve the ductility of the structure as much as possible, vertical stirrups can be added to the UHPC ribs to improve the shear resistance of the UHPC ribs; 3) Transverse short steel bars can be set in the mortise to improve the splitting resistance of the UHPC ribs.

[0104] Application examples:

[0105] In this case, based on the specific structural dimensions of a composite structural beam, the above calculation method is used to verify the structural rationality of the composite structural beam, as follows:

[0106] According to the effect design value of permanent action and the effect design value of variable action, the effect design value of vertical shear force under the basic combination of action effects is obtained. And the design value of the effect of the bending moment .

[0107] Elastic modulus of steel , UHPC elastic modulus , , convert UHPC material into steel and obtain the converted cross-section of a single material.

[0108] Iterative calculation based on the cross-section layering method mm, moment of inertia , , m ;

[0109] Design value of horizontal shear effect of steel dowel .

[0110] Obtaining the yield strength of the steel web , steel web thickness ; Standard value of axial tensile strength of UHPC concrete , the thickness of UHPC rib (including reinforced horseshoe), steel tenon spacing =150mm.

[0111] Strength factors of steel dowels and UHPC ribs ; , so the steel tenon failure will occur. This failure mode is ductile and meets the design requirements.

[0112] At the same time, the push-out resistance of the steel tenon corresponding to each failure mode is calculated as follows:

[0113] Characteristic value of horizontal shear bearing capacity corresponding to steel tenon failure :

[0114] = 454kN

[0115] Characteristic value of horizontal shear bearing capacity corresponding to splitting failure of UHPC rib :

[0116]

[0117] Characteristic value of horizontal shear bearing capacity corresponding to shear failure of UHPC rib plate above steel tenon :

[0118]

[0119] Obtaining the push-out resistance of steel dowels in UHPC ribs Among the horizontal shear bearing capacity characteristics corresponding to the three failure modes The minimum, further indicating that Determine the reliability of the failure mode.

[0120] .

[0121] This indicates that the anti-pushout capability meets the requirements.

[0122] Embodiment 2:

[0123] The present embodiment provides a system for calculating the push-out resistance of steel tenons in UHPC ribs, the system comprising a memory (i.e., a storage medium) and a processor, the memory storing computer instructions, the computer instructions being configured to execute the calculation method in Embodiment 1 when running, and the processor executing the computer instructions stored in the memory to execute the calculation method in Embodiment 1; through the calculation system of the present embodiment, after the designer inputs the proposed structural dimensions into the calculation system, it can verify whether the current structural dimensions meet the safety requirements.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calculating the push-out resistance of steel tenons in UHPC ribs, characterized in that: include: S1. Obtain the design value of the vertical shear effect of the composite structural beam under the proposed structural size Design values ​​of the effects of bending moment ; S2. Design value based on the geometric parameters of the cross section of the composite structure beam and the effect of vertical shear force Design values ​​of the effects of bending moment , calculate the design value of the horizontal shear effect of the steel tenon ; S3. Calculation of the push-out resistance of steel tenons in UHPC ribs ; S4, if satisfied , it indicates that the anti-pushout capability meets the requirements, otherwise it is necessary to adjust the structural dimensions and re-enter step S1 for calculation; where, is the importance coefficient of the composite structural beam, is the material partial factor, The spacing of the steel tenons; Step S3 calculates the push-out resistance of the steel tenon in the UHPC rib plate , specifically: The composite structural beam has three failure modes under the action of horizontal shear force: steel tenon failure, UHPC rib splitting failure, and UHPC rib shear failure. The horizontal shear bearing capacity characteristic values ​​under the three failure modes are calculated respectively, and the minimum value is selected as the anti-push-out capacity of the steel tenon in the UHPC rib. ; Characteristic value of horizontal shear bearing capacity under failure mode of steel dowel for: （2）， Characteristic value of horizontal shear bearing capacity of UHPC ribbed slab under splitting failure mode for: （3）， Characteristic value of horizontal shear bearing capacity of UHPC ribbed slab under shear failure mode for: （4）， Push-out resistance of steel tenons in UHPC ribs for: （5）， in, is the standard value of axial tensile strength of UHPC concrete, is the thickness of the UHPC rib, is the yield strength of the steel web, is the thickness of the steel web, is the arrangement spacing of the steel tenons, is the adjustment factor, is the shear area of ​​UHPC concrete corresponding to a single steel tenon, .

2. The method for calculating the push-out resistance of the steel tenon in the UHPC rib according to claim 1 is characterized in that: The specific steps in step S2 are as follows: S2.

1. Convert the cross section of the composite structural beam into a cross section of a single material; S2.

2. Design value based on the effect of bending moment The distance from the neutral axis NA to the top of the section is obtained iteratively using the section layering method. , and calculate the moment of inertia of the cross section about the neutral axis NA ; S2.

3. According to the moment of inertia of the cross section about the neutral axis NA and the design value of the effect of vertical shear , calculate the design value of the horizontal shear effect of the steel tenon .

3. The method for calculating the push-out resistance of the steel tenon in the UHPC rib according to claim 2 is characterized in that: In step S2.1, the cross section of the composite structural beam is converted into a cross section of a single material, specifically: Multiply the thickness of the UHPC rib plate in the cross section of the composite structure beam and the width of the UHPC bridge deck by , and obtain the cross section of a single material; among them, the elastic modulus ratio , is the elastic modulus of the steel web, is the elastic modulus of UHPC concrete.

4. The method for calculating the push-out resistance of the steel tenon in the UHPC rib according to claim 2, characterized in that: Calculate the design value of the horizontal shear effect of the steel dowel in step S2.3 , specifically: （1）， in, S is the static moment of the section below the height of the steel tenon, is the width of the steel tenon in the section.

5. The method for calculating the push-out resistance of the steel tenon in the UHPC rib according to claim 1, characterized in that: The calculation method also includes: calculating the strength factors of the steel tenons and the UHPC ribs based on the proposed structural dimensions , if the intensity factor <4.5 indicates that the structure is reasonable, otherwise the strength factor needs to be recalculated after adjusting the structural dimensions. ; Among them, the strength factor of steel tenon and UHPC rib is for: （6）， in, is the yield strength of the steel web; is the thickness of the steel web, is the standard value of axial tensile strength of UHPC concrete, is the thickness of the UHPC rib.

6. The method for calculating the push-out resistance of the steel tenon in the UHPC rib according to claim 5, characterized in that: According to the intensity factor The method for determining the failure mode between the steel tenon and the UHPC rib plate under the current structural size is: when When , it indicates that the steel tenon failure occurs between the steel tenon and the UHPC rib plate under the action of horizontal shear force; when When , it indicates that the splitting failure of the UHPC rib occurs between the steel tenon and the UHPC rib under the action of horizontal shear force; when , it indicates that shear failure of the UHPC rib occurs between the steel tenon and the UHPC rib under the action of horizontal shear force.

7. A system for calculating the push-out resistance of steel tenons in UHPC ribs, characterized in that: The system includes a memory and a processor, and when the processor runs the computer instructions stored in the memory, the computing method according to any one of claims 1 to 6 is executed.

8. A storage medium, characterized in that: The storage medium stores computer instructions, and the computer instructions are configured to execute the calculation method according to any one of claims 1 to 6 when executed.

Images