Method and device for testing model of girder structure

Abstract

This invention relates to a test method and apparatus for truss structure models. Existing truss structure test apparatuses suffer from poor reliability and complex construction. In this apparatus, the reaction wall is located vertically at the top of one side of the ground panel; the upper part of the node plate is embedded in the bottom of the concrete beam, and the lower part of the node plate is connected to the ground panel via steel web members and pin hinge supports; longitudinal external prestressed anchor beams are provided on both sides of the concrete beam, and a horizontal loading rod is provided between one side of the external prestressed anchor beam and the reaction wall. This invention converts oblique tension and compression forces into horizontal loading, eliminating the need for complex oblique loading devices; horizontal loads can be directly applied to the prestressed anchor beams, and the horizontal loading surface does not require special treatment, significantly simplifying the apparatus structure; the external prestressing member is designed, converting axial force into external prestressing application, effectively reducing prestress loss, accurately measuring the magnitude of axial force, and the axial force application position can be adjusted along the beam height, resulting in more reliable test results.

Description

Technical Field

[0001] This invention relates to the field of bridge structural model testing technology, specifically to a method and apparatus for testing truss structure models. Background Technology

[0002] Truss bridges are a common structural type used in railway bridges, offering advantages such as high structural stiffness and fast construction speed, thus enjoying widespread application. In truss structures, the steel web members are connected to the concrete beams via gusset plates, which exhibit complex stress distribution and interaction with the concrete beams. Model tests are generally conducted during the design process of truss bridges.

[0003] However, the web members at the nodes of the truss structure are diagonal members, with one side of the web member bearing compression and the other side bearing tension. If the loading is based on the actual stress form, it is difficult to realize in model tests, and a complex diagonal loading device needs to be designed.

[0004] Furthermore, in actual bridges, longitudinal prestressing is incorporated into the concrete beams, or some cable-stayed truss structures have stay cables. Therefore, longitudinal compressive stress exists within the concrete beams. Traditionally, this compressive stress in concrete beams is achieved by pre-embedding ducts within the concrete beam and then tensioning the longitudinal prestressing tendons. However, this method requires pre-embedding larger diameter tendons when the axial force is high, resulting in larger duct diameters. Larger ducts reduce the cross-sectional area and detail, leading to differences from the actual bridge cross-section. This discrepancy between model test results and actual bridge results affects the reliability of the model tests.

[0005] Furthermore, the prestressed steel strands may experience prestress loss due to friction with the pipe wall, thereby reducing compressive stress. When anchoring prestressed steel strands at the ends of model beams, if the axial force is large and the beam cross-section is small, sufficient anchorage space is required. Moreover, the prestressed anchorage at the beam ends occupies the horizontal force loading position. Therefore, the end loading position needs to be specially designed, and the end structure is relatively complex.

[0006] Therefore, it is necessary to design new experimental devices to overcome the above-mentioned shortcomings. Summary of the Invention

[0007] The purpose of this invention is to provide a test method and apparatus for truss structure models to solve the problems of poor reliability and complex construction of existing test apparatuses.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A test device for a truss structure model, the device comprising a ground panel, reaction wall, concrete beam, gusset plate, steel web members, pin hinge support, and external prestressed anchor beam;

[0010] The reaction wall is located on the top of one side of the ground panel and is vertically installed;

[0011] The upper part of the node plate is embedded in the bottom of the concrete beam, and the lower part of the node plate is connected to the ground panel through the steel web and the pin hinge support.

[0012] The concrete beam has longitudinal external prestressed anchor beams on both sides of its transverse direction, and a horizontal loading rod is provided between the external prestressed anchor beam on one side and the reaction wall.

[0013] Furthermore, the concrete beam is pre-set with transverse prestressed tendon channels, and anchor plates are provided at both ends of the prestressed tendon channels.

[0014] The external prestressing tendons pass through the external prestressing anchor beam and the anchor plate and are inserted into the prestressing tendon duct, with both ends anchored to the outside of the external prestressing anchor beam.

[0015] Furthermore, the concrete beam is supported by support rods;

[0016] The support rod includes a vertical support rod and a horizontal support rod. The bottom end of the vertical support rod is fixed to the ground panel, and the horizontal support rod is fixed to the side of the vertical support rod. The concrete beam is supported above the horizontal support rod.

[0017] Furthermore, the top surface of the transverse support rod is provided with a longitudinal channel steel, the groove of the channel steel faces upward and is provided with a roller, the roller is arranged along the length direction of the channel steel, and a gap is left between the two sides of the roller and the channel steel.

[0018] A support pad is provided on the bottom surface of the concrete beam, and the support pad is located on the top surface of the roller.

[0019] Furthermore, the external prestressed anchor beam includes a top plate, a bottom plate, and two side plates. The side plates have longitudinally oriented strip holes, and the external prestressed tendons are located within the strip holes.

[0020] Furthermore, the top of the steel web member is fixed to the bottom of the node plate;

[0021] The steel web members are arranged diagonally and in pairs, and their bottom ends are connected to the ground panel through pin hinge supports.

[0022] Furthermore, one end of the horizontal loading rod is fixed to the reaction wall, and the other end of the horizontal loading rod is fixed to the external prestressed anchor beam;

[0023] The horizontal loading rod is a jack.

[0024] On the other hand, a test method for a truss structure model is provided, the method being implemented based on the aforementioned apparatus, including:

[0025] The oblique tension and compression force is converted into horizontal loading. Horizontal loads are applied to the external prestressed anchor beam through the horizontal loading rod, and then to the concrete beam, so that the axial force state and magnitude of the steel web members are close to the actual axial force.

[0026] Furthermore, the method also includes:

[0027] The axial force is converted into external prestress and applied to the concrete beam through external prestressing tendons and external prestressing anchor beams, thereby reducing prestress loss.

[0028] Furthermore, the method also includes:

[0029] Longitudinal strip holes are opened on the side of the externally prestressed anchor beam, and the position of the externally prestressed tendons in the strip holes can be changed longitudinally.

[0030] The concrete beam is moved longitudinally using channel steel and rollers.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] This invention provides a test method and apparatus for truss structure models, which converts oblique tension and compression forces into horizontal loading, eliminating the need for complex oblique loading devices. Horizontal loads can be directly applied to prestressed anchored beams, and the horizontal loading surface requires no special treatment, significantly simplifying the device structure.

[0033] In addition, the present invention incorporates an external prestressing component in the test apparatus, which converts axial force into external prestressing, effectively reducing prestress loss, accurately measuring the magnitude of axial force, and allowing the axial force application position to be adjusted along the beam height, resulting in more reliable test results. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0035] Figure 1 This is an elevation view of the model of the present invention.

[0036] Figure 2 This is a plan view of the model of the present invention.

[0037] Figure 3 This is a side view of the model of the present invention.

[0038] Figure 4 This is an elevation view of the web end base of the pin hinge support.

[0039] Figure 5 This is a plan view of the web end base of the pin hinge support.

[0040] Figure 6 This is an elevation view of the base of the grounding end of the pin hinge support.

[0041] Figure 7 This is a plan view of the base of the grounding end of the pin hinge support.

[0042] Figure 8 This is an elevation view of an externally prestressed anchored beam.

[0043] Figure 9 This is a side view of an externally prestressed anchored beam.

[0044] Figure 10 This is a structural diagram of the combination of channel steel and rollers.

[0045] 1-Concrete beam, 2-External prestressed anchor beam, 3-External prestressed tendon, 4-Node plate, 5-Channel steel, 6-Roller, 7-Support rod, 8-Support pad, 9-Steel web member, 10-Pin hinge support, 11-Ground panel, 12-Reaction wall, 13-Horizontal loading rod, 14-Anchor plate, 15-Web end base, 16-Grounding end base. Detailed Implementation

[0046] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0047] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "setting," etc., should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] In a specific implementation, the length direction of the externally prestressed anchor beam 2 is defined as longitudinal, and the direction perpendicular to it is defined as transverse.

[0050] like Figure 1-3 This invention provides a test device for a truss structure model. The device includes a truss assembly, a support assembly, an external prestressing assembly, a horizontal loading assembly, and a longitudinal and transverse movement assembly. The truss assembly includes a concrete beam 1, a node plate 4, steel web members 9, and a pin hinge support 10. The support assembly includes a ground panel 11, support rods 7, and support pads 8. The external prestressing assembly includes an external prestressing anchor beam 2, external prestressing tendons 3, and anchor plates 14. The horizontal loading assembly includes a reaction wall 12 and a horizontal loading rod 13. The longitudinal and transverse movement assembly includes channel steel 5 and rollers 6. Specifically:

[0051] The reaction wall 12 is located on the top of one side of the ground panel 11 and is vertically installed. The upper part of the node plate 4 is embedded in the bottom of the concrete beam 1, and the lower part of the node plate 4 is connected to the ground panel 11 through steel web members 9 and pin hinge supports 10. The top of the steel web members 9 is fixed to the bottom of the node plate 4. The steel web members 9 are arranged diagonally and in pairs, and their bottom ends are connected to the ground panel 11 through pin hinge supports 10. The pin hinge support 10 includes a web end base 15 and a ground end base 16, as shown below. Figure 4-7 The web end base 15 has one lug, and the ground end base 16 has two lugs, which are inserted into each other and connected by a pin. Since only a portion of the actual length of the steel web member 9 is used in the test, but the stress state of the steel web member 9 is related to the calculated length and boundary conditions, in this device, the steel web member 9 and the ground panel 11 are connected by a pin hinge. Through the pin hinge connection, the end of the web member 9 can rotate in the direction of force, which is consistent with the constraint method of the web member of the actual bridge.

[0052] Longitudinal external prestressed anchor beams 2 are provided on both sides of the concrete beam 1. A horizontal loading rod 13 is installed between one side of the external prestressed anchor beam 2 and the reaction wall 12. One end of the horizontal loading rod 13 is fixed to the reaction wall 12, and the other end is fixed to the external prestressed anchor beam 2. The horizontal loading rod 13 is a jack. The horizontal loading rod 13 can directly apply horizontal loads to the external prestressed anchor beam 2, and no other special treatment is required for the horizontal loading surface.

[0053] The concrete beam 1 has pre-set transverse prestressing tendon channels. When applying external prestress, the external prestressing tendons 3 are arranged symmetrically on both sides of the concrete beam 1, and the ends of the prestressing tendons 3 are anchored to the outside of the external prestressing anchor beam 2. When applying axial force, this device applies it in the form of external prestressing based on the above structure, and applies it symmetrically on both sides of the concrete beam 1 through the external prestressing anchor beam 2. Moreover, the position of the external prestressing anchor beam 2 can be adjusted along the beam height to achieve different stress states and magnitudes in the concrete beam 2.

[0054] like Figure 8-9 The external prestressed anchor beam 2 includes a top plate, a bottom plate and two side plates. The side plates have longitudinally oriented strip holes. The external prestressed tendons 3 are located in the strip holes and can change position along the strip holes.

[0055] The concrete beam 1 is supported by support rods 7, which include vertical support rods and horizontal support rods. The bottom end of the vertical support rod is fixed to the ground panel 11, and the horizontal support rod is fixed to the side of the vertical support rod. The concrete beam 1 is supported above the horizontal support rod.

[0056] like Figure 10 The top surface of the transverse support rod is provided with a longitudinal channel steel 5. The groove of the channel steel 5 faces upward and is equipped with a roller 6. The roller 6 is arranged along the length of the channel steel 5, and gaps are left between the roller 6 and the channel steel 5 on both sides. The bottom surface of the concrete beam 1 is provided with a support plate 8, which is located on the top surface of the roller 6 and slides longitudinally. The concrete beam 2 outside the node area is in a cantilever state. In order to prevent large deflection due to excessive cantilever length, vertical restraint is used at the beam end of the concrete beam 2. In order to prevent the vertical restraint friction from weakening the horizontal load, this device allows the beam end to slide freely longitudinally, which can effectively avoid the above-mentioned weakening effect.

[0057] Based on the above-mentioned device, truss structure model tests can be conducted, and the methods include:

[0058] 1. The oblique tension and compression force is converted into horizontal loading. The horizontal load is applied to the external prestressed anchor beam 2 through the horizontal loading rod 13, and then to the concrete beam 1, so that the axial force state and magnitude of the steel web member 9 are close to the actual axial force.

[0059] This operation eliminates the need for complex oblique loading components in the sample apparatus, resulting in a simpler overall structure and easier implementation.

[0060] 2. The axial force is converted into external prestress and applied to the concrete beam 1 through the external prestressing tendons 3 and the external prestressing anchor beam 2, thereby reducing prestress loss.

[0061] This operation not only reduces prestress loss and facilitates accurate measurement of axial force, but also allows for adjustment of the axial force application position along the beam height. Axial force can be measured by installing a pressure gauge inside the external prestressing anchor plate, while external prestress can be measured by attaching strain gauges to the external prestressing tendons 3.

[0062] 3. Longitudinal slots are made on the side of the externally prestressed anchor beam 2, allowing the position of the externally prestressed tendons 3 within these slots to be changed longitudinally. By using the channel steel 5 and rollers 6 to move the concrete beam 1 longitudinally, different prestresses can be applied to the concrete beam 1.

[0063] After the experimental setup was constructed, strain gauges were attached to the surfaces of the node plate 4, steel web members 9, and concrete beam 1 to measure the strain under horizontal loading. The strain was converted into stress to determine the stress state of the components during loading, as well as the bonding and slippage state between the steel node plate 4 and the concrete beam 1. This allows for the evaluation of the stress state of the actual structure during operation. Horizontal displacement sensors were also placed at the ends of the concrete beam 1 to test its horizontal displacement during horizontal loading.

[0064] The present invention incorporates an external prestressing component in the test apparatus, which converts axial force into external prestressing, effectively reducing prestress loss, accurately measuring the magnitude of axial force, and allowing the axial force application position to be adjusted along the beam height, resulting in more reliable test results.

[0065] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A test apparatus for a truss structure model, characterized in that: The device includes a ground panel (11), a reaction wall (12), a concrete beam (1), a node plate (4), a steel web member (9), a pin hinge support (10), and an external prestressed anchor beam (2). The reaction wall (12) is located on the top of one side of the ground panel (11) and is set vertically; The upper part of the node plate (4) is embedded in the bottom of the concrete beam (1), and the lower part of the node plate (4) is connected to the ground panel (11) through the steel web member (9) and the pin hinge support (10). The concrete beam (1) is provided with longitudinal external prestressed anchor beams (2) on both sides of the transverse direction, and a horizontal loading rod (13) is provided between the external prestressed anchor beam (2) on one side and the reaction wall (12). The concrete beam (1) is supported by a support rod (7); The support rod (7) includes a vertical support rod and a horizontal support rod. The bottom end of the vertical support rod is fixed to the ground panel (11), and the horizontal support rod is fixed to the side of the vertical support rod. The concrete beam (1) is supported above the horizontal support rod. The top surface of the transverse support rod is provided with a longitudinal channel steel (5), the groove of the channel steel (5) faces upward and is provided with a roller (6), the roller (6) is arranged along the length direction of the channel steel (5), and there is a gap between the two sides of the roller (6) and the channel steel (5). The bottom surface of the concrete beam (1) is provided with a support pad (8), which is located on the top surface of the roller (6).

2. The test apparatus for truss structure model according to claim 1, characterized in that: The concrete beam (1) has a pre-set transverse prestressed tendon channel, and anchor plates (14) are provided at both ends of the prestressed tendon channel. The external prestressed tendon (3) passes through the external prestressed anchor beam (2) and the anchor plate (14) and is inserted into the prestressed tendon channel, with both ends anchored to the outside of the external prestressed anchor beam (2).

3. The test apparatus for truss structure model according to claim 2, characterized in that: The external prestressed anchor beam (2) includes a top plate, a bottom plate and two side plates. The side plates have longitudinal strip holes, and the external prestressed tendons (3) are located in the strip holes.

4. The test apparatus for truss structure model according to claim 3, characterized in that: The top of the steel web member (9) is fixed to the bottom of the node plate (4); The steel web members (9) are arranged diagonally and in pairs, and their bottom ends are connected to the ground panel (11) through pin hinge supports (10).

5. The test apparatus for truss structure model according to claim 4, characterized in that: One end of the horizontal loading rod (13) is fixed to the reaction wall (12), and the other end of the horizontal loading rod (13) is fixed to the external prestressed anchor beam (2). The horizontal loading rod (13) is a jack.

6. A test method for truss structure models, characterized in that: The method is implemented based on the apparatus of claim 5, and includes: The oblique tension and compression force is converted into horizontal loading. The horizontal load is applied to the external prestressed anchor beam (2) through the horizontal loading rod (13), and then to the concrete beam (1), so that the axial force state and magnitude of the steel web member (9) are close to the actual axial force.

7. The test method for truss structure model according to claim 6, characterized in that: The method further includes: The axial force is converted into external prestress and applied to the concrete beam (1) through external prestressing bundles (3) and external prestressing anchor beams (2), thereby reducing prestress loss.

8. The test method for truss structure model according to claim 7, characterized in that: The method further includes: A longitudinal strip hole is opened on the side of the external prestressed anchor beam (2), and the position of the external prestressed tendon (3) in the strip hole can be changed longitudinally. The concrete beam (1) is moved longitudinally by means of channel steel (5) and rollers (6).

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