A bending-torsional buckling test system and test method for rectangular tube flange curved composite beams

Abstract

A bending-torsion buckling test system and test method for rectangular tube flange curved composite beams, belonging to a test loading device. In order to solve the problems that the existing test loading system cannot or accurately measure the bending-torsion buckling failure performance and bending-torsion buckling bearing capacity of rectangular tube flange curved composite beams under different curvature radii. The present invention can vertically support, torsionally limit and laterally limit the beam ends of applicable test beams with different curvature radii and different cross-sectional sizes through the setting of a support base and vertical and lateral limiting mechanisms, so as to avoid relative torsion between the upper flange and the web, and prevent distortion and deformation of the end section. At the same time, the use of bearings and elastic gaskets can avoid redundant longitudinal constraints on the test beam to the greatest extent; by setting a loading jack that can slide freely laterally and a knife hinge support under the loading point, there is no redundant constraint at the loading point, thereby ensuring that the test beam can freely undergo bending-torsion buckling failure as the load increases, so that the test beam achieves an ideal bending-torsion buckling failure effect.

Description

Technical Field

[0001] The invention belongs to a test loading device, and in particular relates to a bending-torsion buckling test system and a test method for a rectangular tube flange curved composite beam. Background Art

[0002] The steel-concrete composite structure conforms to the development concept of green, high-performance and sustainable engineering. It has the characteristics of light and beautiful steel, convenient construction and recyclability, and at the same time has the mechanical performance advantages of the composite materials. The rectangular tube flange curve composite beam is a new structure formed by replacing the flange of the traditional I-beam flat plate with a rectangular tube with a certain curvature. Concrete is poured in the rectangular tube. The rectangular tube flange curve composite beam inherits the technical and economic performance advantages of the traditional I-beam, greatly improves the defect of insufficient stability of the traditional I-beam, and the significantly improved bending-torsion buckling strength makes it particularly suitable for the construction needs of curved composite beam bridges with prominent bending-torsion coupling effects.

[0003] The existing test loading system is only used for the overall stable bearing capacity test of steel beams with lateral constraints under single-point loading. For example, the Chinese patent "Overall Stability Test Loading System for Laterally Constrained Steel Beams under Single-Point Loading" is disclosed in the publication number "CN204694463U". This patent limits the lateral displacement and torsion of the test steel beam at the loading point through the lateral constraint device, and releases the bending constraint and vertical displacement constraint inside and outside the plane of the steel beam at the loading point through the vertical rolling of the vertical rolling bearing and the horizontal rotation of the horizontal rotation device. Although this test loading system is suitable for the overall stable bearing capacity test of I-beams with lateral constraints, it is not suitable for the bending-torsion buckling performance test of rectangular tube flange curved composite beams with single-point loading due to the bending-torsion coupling stress characteristics of curved composite beams.

[0004] The determination of the elastic-plastic flexural-torsional buckling bearing capacity of rectangular tube flange curved composite beams is measured through flexural-torsional buckling failure tests, and the flexural-torsional coupling effect caused by the mid-span vertical load is the key factor that exacerbates its flexural-torsional buckling failure risk. The flexural-torsional buckling failure test of rectangular tube flange curved composite beams strictly requires that the test beam can freely produce flexural-torsional buckling failure forms including vertical displacement, lateral displacement and cross-sectional torsion under the action of the mid-span vertical load, under the premise of ensuring that there is no lateral displacement, torsion and distortion of the cross section at the beam end support position. The lateral constraints on the loading point of the test beam generated by the above-mentioned and conventional test loading systems and the restrictions on the flexural-torsional buckling failure forms of the test beams by the loading device will cause the rectangular tube flange curved composite beams to be unable to freely produce lateral displacement and cross-sectional torsion, which in turn causes the test beams to be affected by the constraints of the test system and unable to produce flexural-torsional buckling failure forms, and the required test results cannot be obtained. At the same time, since the torsional stiffness of the upper flange of the rectangular tube flange curve composite beam is much greater than the torsional stiffness of the web, the end section is more prone to relative torsional deformation between the upper flange and the web when subjected to vertical loads. This is a unique technical problem that distinguishes this new type of composite beam from traditional beam structures. Since the torsional stiffness of the flange and the web of the traditional beam structure is similar, there is no obvious relative torsional deformation between the two end sections. Therefore, compared with traditional beam structures, the bending buckling test of the rectangular tube flange curve composite beam has very strict protection requirements for the boundary conditions of the beam end support position, and its end section must be effectively constrained to achieve the ideal boundary conditions required by the test. The above-mentioned and conventional test loading systems do not effectively constrain the ends of the test beams, which will cause the upper flange steel tube at the end of the test beam to twist relative to the web during the test, causing distortion and buckling of the end section of the test beam, affecting the overall bending-torsion buckling failure state of the test beam.

[0005] The limitations of the above and conventional test loading systems will result in the inability of rectangular tube flange curved composite beams to undergo ideal flexural-torsional buckling failure forms under single-point loading, and ultimately the inability or accuracy of the flexural-torsional buckling performance of rectangular tube flange curved composite beams under flexural-torsional buckling failure, such as stress-strain response law, bearing capacity and stiffness development, and ultimate bearing capacity, cannot be measured through tests. Therefore, a test system and test method that can truly and accurately measure the flexural-torsional buckling performance of rectangular tube flange curved composite beams with different curvature radii is urgently needed in research and application practice. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the constraints imposed on the test beam by the existing test loading system make it impossible for the rectangular tube flange curved composite beam to produce the required bending-torsional buckling failure morphology, so the bending-torsional buckling performance of the rectangular tube flange curved composite beam cannot be obtained or accurately obtained, and the relative torsion problem between the tube flange and the web unique to the rectangular tube flange curved composite beam and the applicability of the loading system when the test beam has different curvature radii cannot be specifically solved, thereby providing a bending-torsional buckling test system and a test method for rectangular tube flange curved composite beams.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] A bending-torsion buckling test system for a rectangular tube flange curved composite beam, comprising two supporting devices and a vertical loading device, wherein the two supporting devices are used for supporting and limiting the ends of the test beam, and the vertical loading device is installed between the two supporting devices and is located above the test beam, and is used for vertical loading of the test beam;

[0009] Each supporting device comprises a supporting base, two steel columns, an upper cross beam, a support, a vertical limiting mechanism and two groups of lateral limiting mechanisms; the two steel columns are installed side by side horizontally above the supporting base, the upper cross beam is installed at the top ends of the two steel columns, the vertical limiting mechanism and the support are arranged between the two steel columns from top to bottom, the vertical limiting mechanism is installed just below the upper cross beam, and the support is placed above the supporting base; the end of the test beam is placed on the support, and the telescopic end of the vertical limiting mechanism abuts against the upper surface of the test beam; the two groups of lateral limiting mechanisms are installed on the two steel columns from top to bottom, respectively, and are located between the two steel columns, and the two groups of lateral limiting mechanisms clamp the upper flange and the lower flange of the test beam respectively, and the vertical limiting mechanism and the two groups of lateral limiting mechanisms avoid relative torsion between the upper flange and the web at the end of the test beam, thereby preventing the end section of the test beam from being distorted.

[0010] Furthermore, the support base includes an upper top plate, a lower bottom plate, a connecting web I, two grounding bolts, a plurality of stiffening ribs I and two lifting handles. The upper top plate and the lower bottom plate are arranged opposite to each other in the upper and lower directions, and are fixedly connected by the connecting web I and the plurality of stiffening ribs I. The length of the connecting web I is less than the length of the upper top plate and the lower bottom plate, and is installed at a position in the middle of the upper top plate and the lower bottom plate in the length direction. A waist hole I is respectively opened at both ends of the upper top plate, and the opening direction of the waist hole I is consistent with the width direction of the upper top plate. A waist hole II is respectively opened at both ends of the lower bottom plate, and the opening direction of the waist hole II is consistent with the width direction of the lower bottom plate. The waist hole I and the waist hole II are arranged opposite to each other in the upper and lower directions, and the grounding bolts pass through the waist hole I and the waist hole II in sequence and are anchored in the ground, and the two lifting handles are respectively installed at both ends of the upper top plate.

[0011] Furthermore, each steel column includes two side plates, a connecting web II, an upper cover plate, a lower cover plate, a plurality of stiffening ribs II and a plurality of triangular stiffening ribs; the two side plates are arranged laterally opposite to each other and are fixedly connected with the plurality of stiffening ribs II through the connecting web II; the upper cover plate is fixed to the top ends of the two side plates, the lower cover plate is fixed to the bottom ends of the two side plates, and the plurality of triangular stiffening ribs are respectively connected between the side plates and the lower cover plate and between the connecting web II and the lower cover plate.

[0012] Furthermore, the upper crossbeam is an I-beam, and both ends of the upper crossbeam are connected to the upper cover plates of the two steel columns through a bottom plate on the upper crossbeam and a plurality of bolts.

[0013] Furthermore, the support includes a support base and a cylindrical steel, and the support base is placed on the upper top plate of the support base; the cylindrical steel in one of the support devices is radially placed above the support base, and the cylindrical steel in the other support device is radially welded above the support base; the axial direction of the cylindrical steel is set toward the direction of the steel column, and the end of the test beam is placed on the cylindrical steel.

[0014] Furthermore, the vertical limiting mechanism includes an internal threaded sleeve, a stud and an elastic gasket; one end of the internal threaded sleeve is installed on the lower surface of the upper cross beam, one end of the stud is screwed to the other end of the internal threaded sleeve, and the elastic gasket is installed on the other end of the stud.

[0015] Furthermore, each set of lateral limit mechanisms includes two limit support assemblies, which are respectively installed on two steel columns relatively to each other; each limit support assembly includes two bearing support plates, a bearing support, a cylindrical roller bearing, four connecting bolts and four adjusting screws; the two bearing support plates are respectively arranged on both sides of the steel column and fixedly connected by four connecting bolts; the bearing support plate on the outer side of the steel column abuts against the outer side of the steel column, the four adjusting screws are vertically screwed on the bearing support plate on the inner side of the steel column, and the ends of the four adjusting screws abut against the inner side of the steel column; the bearing support is fixedly connected to the bearing support plate on the inner side of the steel column, the cylindrical roller bearing is installed in the bearing support, the connecting line direction of the cylindrical roller bearings of each set of lateral limit mechanisms is perpendicular to the tangent direction of the test beam at this point, and the outer circumferential surface of the cylindrical roller bearing abuts against the upper flange or lower flange of the test beam.

[0016] Furthermore, the vertical loading device includes a supporting beam, a jack and a knife hinge support; the supporting beam is arranged between the two supporting devices and is above the test beam; the fixed end of the jack is installed on the supporting beam and can move along the extension direction of the supporting beam; the knife hinge support is placed at the top of the middle position of the test beam, and the telescopic end of the jack abuts against the upper end surface of the knife hinge support.

[0017] Furthermore, the knife hinge support includes an upper steel plate and a lower steel plate, and the middle position of the upper steel plate and the lower steel plate is hinged.

[0018] A test method for a bending-torsion buckling test system of a rectangular tube flange curved composite beam, characterized in that the specific test process is as follows:

[0019] Step 1: According to the size of the central angle of the test beam, adjust the positions of the two support bases within a certain range while the grounding bolts are fixed;

[0020] Step 2: Place the two ends of the test beam on the cylindrical steels in the two support bases respectively, and adjust the position of the test beam so that the support base is perpendicular to the tangent direction of the end of the test beam, ensuring that the lateral limit mechanisms on both sides of the test beam correspond to the abutment points of the test beam;

[0021] Step 3, screw down the stud in the vertical limit mechanism so that the stud extends out of the internal threaded sleeve, and the elastic gasket on the stud presses against the upper flange of the test beam to prevent the upper flange and the web at the end of the test beam from twisting relative to each other;

[0022] Step 4: The upper flange and the lower flange of the test beam are clamped by two sets of lateral limiting mechanisms arranged above and below, respectively, so that both ends of the test beam are integrally laterally limited by the two sets of lateral limiting mechanisms;

[0023] Step 5, place the knife hinge support at the top of the middle position of the test beam, extend the telescopic column of the jack and press against the upper steel plate of the knife hinge support. As the load force of the jack increases, the jack slides along the supporting beam toward the bending and torsion direction of the test beam. The telescopic end of the jack always abuts against the upper steel plate, where the upper steel plate is always in a horizontal state, and the lower steel plate flips with the inclination of the upper flange of the test beam, so that the jack always applies load to the loading point of the test beam.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present application provides two support bases to adjust the angle of the support base within a certain range, so as to be suitable for the bending-torsion buckling failure test of rectangular tube flange curved composite beams with different curvature radii.

[0026] 2. The present application can perform torsion limitation and lateral limitation on the end sections of rectangular tube flange curved composite beams of different cross-sectional sizes through a vertical limiting mechanism and two sets of lateral limiting mechanisms, thereby avoiding relative torsion between the upper flange and the web at the end of the test beam, and effectively preventing distortion and deformation of the end section of the test beam. At the same time, the use of bearings and elastic gaskets can avoid unnecessary longitudinal constraints on the test beam to the greatest extent.

[0027] 3. The present application ensures that the test beam can freely deform laterally under flexural-torsional buckling by setting a jack that can slide freely without restraint laterally, and ensures that the test beam can freely twist under flexural-torsional buckling by setting a knife-hinge support under the loading point, thereby eliminating the effect of redundant constraints at the loading point while ensuring that the direction of action of the loading force remains vertically unchanged, and ensuring that the rectangular tube flange curved composite beam can freely undergo flexural-torsional buckling failure mode as the load increases, thereby achieving an ideal flexural-torsional buckling failure effect.

[0028] 4. The support device of the present application is composed of multiple functional components, has a very high degree of assembly and good technical and economic performance. After overall assembly, it can simultaneously realize the combined functions of serving as a test beam support device and as a test beam lateral limit device. Each functional component has a light structure, saves steel, is easy to assemble, and has low assembly difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are incorporated as part of this application and are used to provide a further understanding of the present invention.

[0030] Figure 1 It is the front view of the present invention.

[0031] Figure 2 It is an axonometric view of the present invention.

[0032] Figure 3 It is a structural schematic diagram of the lateral limiting mechanism.

[0033] Figure 4 It is a structural schematic diagram of the vertical limiting mechanism.

[0034] Figure 5 Schematic diagram of the loading relationship between the vertical loading device and the test beam.

[0035] Figure 6 It is the structural schematic diagram of the knife hinge support.

[0036] Figure 7 Schematic diagram of the position of the test beam with a central angle of 0.4 rad supported by the supporting device.

[0037] Figure 8 Schematic diagram of the position of the test beam with a central angle of 0.2 rad supported by the supporting device.

[0038] Fig. 9 Schematic diagram of the flexural-torsional buckling state produced at the loading point of the test beam.

[0039] Fig.10 This is a physical picture of the test system when no vertical limit mechanism is added to the support device.

[0040] Fig.11 This is a physical picture of the bending-torsional buckling state of the tested beam without adding a vertical limit mechanism to the support device.

[0041] Description of the accompanying drawings: A-support device; B-vertical loading device; C-test beam; 1-support base; 1-1-upper top plate; 1-1-1-waist hole I; 1-2-lower bottom plate; 1-2-1-waist hole II; 1-3-connecting web I; 1-4-grounding bolt; 1-5-stiffening rib I; 1-6-lifting handle; 2-steel column; 2-1-side vertical plate; 2-2-connecting web II; 2-3-upper cover plate; 2-4-lower cover plate; 2-5-stiffening rib II; 2-6- Triangular stiffening rib; 3-upper beam; 4-support; 4-1-support base; 4-2-cylindrical steel; 5-vertical limiting mechanism; 5-1-inner threaded sleeve; 5-2-stud; 5-3-elastic gasket; 6-lateral limiting mechanism; 6-1-support support plate; 6-2-bearing support; 6-3-cylindrical roller bearing; 6-4-connecting bolt; 6-5-adjusting screw; 7-support beam; 8-jack; 9-knife-reamer support; 9-1-upper steel plate; 9-2-lower steel plate. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0043] See also Figures 1 to 11 The embodiment of the present application provides a bending-torsional buckling test system for a rectangular tube flange curved composite beam, which includes two support devices A and a vertical loading device B. The two support devices A are used to support and limit the ends of the test beam C, that is, the two ends of the test beam C are respectively installed on the two support devices A, and the vertical loading device B is installed between the two support devices A and is located above the test beam C, and is used for vertical loading of the test beam C. The test beam C is a rectangular tube flange curved composite beam.

[0044] See also Figure 1 and Figure 2Each support device A comprises a support base 1, two steel columns 2, an upper cross beam 3, a support 4, a vertical limiting mechanism 5 and two sets of lateral limiting mechanisms 6; the two steel columns 2 are installed side by side horizontally above the support base 1, the upper cross beam 3 is installed at the top of the two steel columns 2, the vertical limiting mechanism 5 and the support 4 are arranged between the two steel columns 2 from top to bottom, the vertical limiting mechanism 5 is installed just below the upper cross beam 3, and the support 4 is placed above the support base 1; The end of the test beam C is placed on the support 4, and the top end of the vertical limiting mechanism 5 abuts against the upper surface of the test beam C; the two groups of lateral limiting mechanisms 6 are respectively installed on the two steel columns 2 from top to bottom and are located between the two steel columns 2, and the two groups of lateral limiting mechanisms 6 clamp the upper flange and the lower flange of the test beam C. The vertical limiting mechanism (5) and the two groups of lateral limiting mechanisms (6) avoid relative twisting between the upper flange and the web at the end of the test beam C, thereby preventing the cross section of the end of the test beam C from being distorted.

[0045] See also Figure 1 and Figure 2 The support base 1 includes an upper top plate 1-1, a lower bottom plate 1-2, a connecting web Ⅰ1-3, two grounding bolts 1-4, a plurality of stiffening ribs Ⅰ1-5 and two lifting handles 1-6. The upper top plate 1-1 and the lower bottom plate 1-2 are arranged opposite to each other up and down, and are fixedly connected by connecting web Ⅰ1-3 and a plurality of stiffening ribs Ⅰ1-5; the length of the connecting web Ⅰ1-3 is less than the length of the upper top plate 1-1 and the lower bottom plate 1-2, and is installed at a position in the middle of the upper top plate 1-1 and the lower bottom plate 1-2 in the length direction; a waist hole Ⅰ1-1-1 is respectively opened at both ends of the upper top plate 1-1, and the waist hole Ⅰ1-1-1 is provided at the bottom of the upper top plate 1-1. The opening direction of 1-1-1 is consistent with the width direction of the upper top plate 1-1; a waist hole Ⅱ1-2-1 is respectively opened at both ends of the lower bottom plate 1-2, and the opening direction of the waist hole Ⅱ1-2-1 is consistent with the width direction of the lower bottom plate 1-2; the waist hole Ⅰ1-1-1 and the waist hole Ⅱ1-2-1 are arranged opposite to each other up and down, and the grounding bolt 1-4 passes through the waist hole Ⅰ1-1-1 and the waist hole Ⅱ1-2-1 in turn and is anchored in the ground, that is, the support base 1 is installed on the ground through two grounding bolts 1-4; the two lifting handles 1-6 are respectively installed at both ends of the upper top plate 1-1, which are used to adjust the support base 1.

[0046] See also Figure 7 and Figure 8, since the grounding bolts 1-4 are anchored on the ground, in order to make this test system suitable for test beams C with different central angles and not too large mobile support base 1, by adjusting the position of the grounding bolts 1-4 in the waist hole Ⅰ1-1-1 and the waist hole Ⅱ1-2-1, the position of the support base 1 can be adjusted within a certain range. The waist hole Ⅰ1-1-1 is 200mm long and 100mm wide, and the waist hole Ⅰ1-1-1 is the same size as the waist hole Ⅱ1-2-1; the diameter of the screw is 50mm, and the diameter of the ground hole is 100mm; this application is applicable to test beams C with a central angle less than 0.4rad.

[0047] See also Figure 1 Each steel column 2 includes two side plates 2-1, a connecting web II 2-2, an upper cover plate 2-3, a lower cover plate 2-4, a plurality of stiffening ribs II 2-5 and a plurality of triangular stiffening ribs 2-6; the two side plates 2-1 are arranged opposite to each other in the transverse direction, and are fixedly connected to the plurality of stiffening ribs II 2-5 through the connecting web II 2-2; the upper cover plate 2-3 is fixed to the top of the two side plates 2-1, the lower cover plate 2-4 is fixed to the bottom of the two side plates 2-1, and the plurality of triangular stiffening ribs 2-6 are respectively connected between the side plates 2-1 and the lower cover plate 2-4 and between the connecting web II 2-2 and the lower cover plate 2-4. The triangular stiffening ribs 2-6 are used to strengthen the rigidity of the column foot and ensure the reliability of the column foot connection.

[0048] See also Figure 2 The upper cross beam 3 is an I-beam, and both ends of the upper cross beam 3 are connected to the upper sealing plates 2-3 of the two steel columns 2 through the bottom plate on the upper cross beam 3 and a plurality of group bolts.

[0049] See also Figure 1 The support 4 includes a support base 4-1 and a cylindrical steel 4-2, and the support base 4-1 is placed on the upper top plate 1-1 of the support base 1; the cylindrical steel 4-2 in one of the support devices A is radially placed above the support base 4-1, and the cylindrical steel 4-2 in the other support device A is radially welded above the support base 4-1; the two supports work together to form a simply supported boundary; the axial direction of the cylindrical steel 4-2 is set toward the direction of the steel column 2, and the end of the test beam C is placed on the cylindrical steel 4-2.

[0050] See also Figure 4, the vertical limiting mechanism 5 includes an internal threaded sleeve 5-1, a stud 5-2 and an elastic gasket 5-3; one end of the internal threaded sleeve 5-1 is installed on the lower surface of the upper cross beam 3, one end of the stud 5-2 is screwed to the other end of the internal threaded sleeve 5-1, and the elastic gasket 5-3 is installed at the other end of the stud 5-2. The outer diameter of the stud 5-2 is determined by the width of the upper flange of the test beam C. The material of the elastic gasket 5-3 is polytetrafluoroethylene, and the thickness of the elastic gasket 5-3 is 10mm. Before the test beam C is subjected to the elastic-plastic bending-torsional buckling failure performance test, the stud 5-2 is screwed down so that the stud 5-2 extends out of the internal threaded sleeve 5-1, and the elastic gasket 5-3 on the stud 5-2 is pressed against the upper flange of the test beam C, avoiding relative twisting of the upper flange of the steel tube concrete at the end of the test beam C and the web, effectively preventing the end section of the test beam C from being distorted. See Fig.11 If the end of the test beam C is not vertically restricted, during the test, the upper flange and web at the end of the test beam C will be twisted relative to each other, and the cross-section of the end of the test beam C will be distorted, affecting the shape of the bending-torsional buckling deformation at the middle loading point of the test beam C. Then, the bending-torsional buckling bearing capacity of the test beam C under single-point loading cannot be tested, resulting in inaccurate measurement results.

[0051] See also Figure 3Each set of lateral limit mechanisms 6 includes two limit support assemblies, and the two limit support assemblies are respectively installed on the two steel columns 2 relative to each other; each limit support assembly includes two bearing support plates 6-1, a bearing support 6-2, a cylindrical roller bearing 6-3, four connecting bolts 6-4 and four adjusting screws 6-5; the two bearing support plates 6-1 are respectively arranged on both sides of the steel column 2 and are fixedly connected by four connecting bolts 6-4; the bearing support plate 6-1 on the outer side of the steel column 2 abuts against the outer side of the steel column 2, the four adjusting screws 6-5 are vertically screwed on the bearing support plate 6-1 on the inner side of the steel column 2, and the ends of the four adjusting screws 6-5 abut against the inner side of the steel column 2, and the limit support assembly is clamped on the steel column 2 under the action of the four connecting bolts 6-4 and the four adjusting screws 6-5. The limit support assembly can move up and down along the height direction of the steel column 2 under the adjustment of the connecting bolt 6-4 and the adjusting screw 6-5 to cope with the test beams C of different sizes and different structural forms. The bearing support 6-2 is welded on the support support plate 6-1 on the inner side of the steel column 2, and the cylindrical roller bearing 6-3 is installed in the bearing support 6-2. The connecting line direction of the cylindrical roller bearing 6-3 of each set of lateral limit mechanisms 6 is perpendicular to the tangent direction of the test beam C, and the outer circumferential surface of the cylindrical roller bearing 6-3 abuts against the upper flange or lower flange of the test beam C. The upper flange of the test beam C is laterally limited by a set of lateral limit mechanisms 6, that is, by two relatively arranged limit support assemblies; the lower flange of the test beam C is laterally limited by a set of lateral limit mechanisms 6. The end of the test beam C is laterally limited as a whole by two sets of lateral limit mechanisms 6. Before conducting the elastoplastic bending-torsional buckling failure performance test on the test beam C, first adjust the positions of the four adjusting screws 6-5 so that the ends of the four adjusting screws 6-5 abut against the inner side of the steel column 2, then adjust the position of the support plate 6-1 on the outer side of the steel column 2 so that it abuts against the outer side of the steel column 2, and finally adjust the nuts on the connecting bolts 6-4 to tighten them; the two sets of lateral limit mechanisms 6 clamp the test beam C.

[0052] See also Figure 5 The vertical loading device B includes a supporting beam 7, a jack 8 and a knife hinge support 9; the supporting beam 7 is arranged between the two supporting devices A and is above the test beam C; the fixed end of the jack 8 is installed on the supporting beam 7 and can move along the extension direction of the supporting beam 7, wherein the sliding friction coefficient of the jack 8 is controlled within 3%; the knife hinge support 9 is placed at the top of the middle position of the test beam C, and the telescopic end of the jack 8 abuts against the upper end surface of the knife hinge support 9.

[0053] See also Figure 6The knife hinge support 9 includes an upper steel plate 9-1 and a lower steel plate 9-2, and the middle position of the upper steel plate 9-1 and the lower steel plate 9-2 is hinged.

[0054] Furthermore, the upper steel plate 9-1 and the lower steel plate 9-2 are connected by a hinge shaft, and the hinge shaft is arranged at a position between the upper steel plate 9-1 and the lower steel plate 9-2. Alternatively, a notch is provided at a middle position of the lower surface of the upper steel plate 9-1 along the extension direction of the test beam, and an integral protrusion is provided at a middle position of the upper surface of the lower steel plate 9-2 along the extension direction of the test beam, and the protrusion on the lower steel plate 9-2 is in the notch of the upper steel plate 9-1, and the upper steel plate 9-1 and the lower steel plate 9-2 are rotated by the protrusion.

[0055] Furthermore, the angle of rotation between the upper steel plate 9-1 and the lower steel plate 9-2 in the knife hinge support 9 is ±15°. When the rotation angle of the upper end face of the test beam is 15°, the lateral bending-torsional buckling deformation is significant. The load displacement curve obtained in the test has a long descending section. The test data is complete and meets the analysis of the entire process of bending-torsional buckling failure of the test beam. If a larger torsion angle is set, the safety hazards of the test will be greatly increased. The knife hinge support 9 releases the mid-span torsion constraint to ensure that there is no redundant constraint in the mid-span of the test beam.

[0056] See also Fig. 9Before the test beam C is subjected to the elastic-plastic bending-torsion buckling failure performance test, the knife hinge support 9 is placed at the top of the middle position of the test beam C. At this time, the upper steel plate 9-1 and the lower steel plate 9-2 are in a parallel state, and the telescopic column of the jack 8 extends and presses on the upper steel plate 9-1 of the knife hinge support 9. As the load force of the jack 8 increases, the test beam C gradually undergoes bending-torsion buckling, and the upper flange of the test beam C bends and twists to one side; in this process, due to the deformation of the test beam C, the position of the loading point is displaced laterally, so the jack 8 slides along the supporting beam 7 so that it always faces the loading point of the test beam C. Since the upper steel plate 9-1 of the knife hinge support 9 is always in contact with the telescopic end of the jack 8, the upper steel plate 9-1 is always in a horizontal state, and the lower steel plate 9-2 is always in contact with the upper end surface of the test beam C, so the lower steel plate 9-2 will tilt with the inclination of the upper end surface of the test beam C, and a certain angle is generated between the upper steel plate 9-1 and the lower steel plate 9-2. Before conducting the bending-torsional buckling failure test, since the telescopic end of the jack is parallel to the upper flange of the test beam and is in surface contact, the upper flange of the test beam will tilt when the vertical load force at the mid-span of the jack gradually increases. However, the vertical load force of the jack will also produce lateral restriction on the bending-torsional buckling of the test beam. Through the setting of the knife-hinge support 9, there is no direct contact between the jack and the upper flange of the test beam, and the hinge connection setting of the upper steel plate 9-1 and the lower steel plate 9-2 in the knife-hinge support 9 no longer produces lateral constraints on the upper flange of the test beam. Therefore, the setting of the knife-hinge support 9 and the vertical load force at the mid-span of the jack ensure the realization of the bending-torsional buckling failure state of the test beam.

[0057] A test method for single-point loading of rectangular tube flange curved composite beams. The specific test process is as follows:

[0058] Step 1: According to the size of the central angle of the test beam C, adjust the positions of the two support bases 1 within a certain range while the grounding bolts 1-4 are fixed;

[0059] Step 2, place the two ends of the test beam C on the cylindrical steel 4-2 in the two support bases 1 respectively, adjust the position of the test beam C so that the support base 1 and the end of the test beam C are vertically arranged, and ensure that the lateral limit mechanisms 6 on both sides of the test beam C correspond to the abutment points of the test beam C;

[0060] Step 3, screw down the stud 5-2 in the vertical limiting mechanism 5 so that the stud 5-2 extends out of the internal threaded sleeve 5-1, and the elastic gasket 5-3 on the stud 5-2 presses against the upper flange of the test beam C to prevent the upper flange and the web at the end of the test beam C from twisting relative to each other;

[0061] Step 4: The upper flange and the lower flange of the test beam C are clamped by two sets of lateral limiting mechanisms 6 arranged above and below, respectively, so that both ends of the test beam C are integrally laterally limited by the two sets of lateral limiting mechanisms 6;

[0062] Step 5, place the knife hinge support 9 at the top of the middle position of the test beam C, and the telescopic column of the jack 8 extends out and presses against the upper steel plate 9-1 of the knife hinge support 9. As the load force of the jack 8 increases, the telescopic end of the jack 8 always abuts against the upper steel plate 9-1, wherein the upper steel plate 9-1 is always in a horizontal state, and the lower steel plate 9-2 flips with the inclination of the upper flange of the test beam C, so that the jack 8 always applies load to the loading point of the test beam C.

[0063] The present application can adjust the position of the support base within a certain range by setting up two support bases, so as to be suitable for the test of elastic-plastic bending-torsional buckling failure of rectangular tube flange curved composite beams with different curvature radii.

[0064] The present application can perform torsional limiting and lateral limiting fixation on the two end portions of rectangular tube flange curved composite beams with different cross-sectional sizes and curvatures less than 0.4 rad through a vertical limiting mechanism and two sets of lateral limiting mechanisms, thereby avoiding relative torsion between the upper flange and the web at the end of the test beam, and effectively preventing distortion and deformation of the end section of the test beam. At the same time, the use of bearings and elastic gaskets can avoid unnecessary longitudinal constraints on the test beam to the greatest extent.

[0065] The present application eliminates unnecessary constraints at the loading point by setting a loading jack that can slide freely laterally and a knife-hinge support under the loading point, thereby ensuring that the rectangular tube flange curved composite beam can freely undergo bending-torsional buckling failure as the load increases, thereby achieving an ideal bending-torsional buckling failure effect.

[0066] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A bending-torsional buckling test system for rectangular tube flange curved composite beams, characterized in that: It comprises two supporting devices (A) and a vertical loading device (B), wherein the two supporting devices (A) are used for supporting and limiting the ends of the test beam (C), and the vertical loading device (B) is installed between the two supporting devices (A) and is located above the test beam (C) for vertical loading of the test beam (C); Each support device (A) comprises a support base (1), two steel columns (2), an upper cross beam (3), a support (4), a vertical limiting mechanism (5) and two sets of lateral limiting mechanisms (6); the two steel columns (2) are installed side by side horizontally above the support base (1), the upper cross beam (3) is installed at the top of the two steel columns (2), the vertical limiting mechanism (5) and the support (4) are arranged between the two steel columns (2) from top to bottom, the vertical limiting mechanism (5) is installed directly below the upper cross beam (3), and the support (4) is placed on the support base (1). The end of the test beam (C) is placed on the support (4), and the telescopic end of the vertical limiting mechanism (5) abuts against the upper surface of the test beam (C); the two groups of lateral limiting mechanisms (6) are respectively installed on the two steel columns (2) from top to bottom and are located between the two steel columns (2), and the two groups of lateral limiting mechanisms (6) respectively clamp the upper flange and the lower flange of the test beam (C). The vertical limiting mechanism (5) and the two groups of lateral limiting mechanisms (6) avoid relative twisting between the upper flange and the web at the end of the test beam (C), thereby preventing the end section of the test beam (C) from being distorted; The support base (1) comprises an upper top plate (1-1), a lower bottom plate (1-2), a connecting web plate I (1-3), two grounding bolts (1-4), a plurality of stiffening ribs I (1-5) and two lifting handles (1-6); the upper top plate (1-1) and the lower bottom plate (1-2) are arranged opposite to each other up and down, and are fixedly connected by connecting web plate I (1-3) and a plurality of stiffening ribs I (1-5); the length of the connecting web plate I (1-3) is less than the length of the upper top plate (1-1) and the lower bottom plate (1-2), and is installed at a position in the middle of the upper top plate (1-1) and the lower bottom plate (1-2) in the length direction; the upper top plate (1-1) A waist hole I (1-1-1) is respectively opened at both ends, and the opening direction of the waist hole I (1-1-1) is consistent with the width direction of the upper top plate (1-1); a waist hole II (1-2-1) is respectively opened at both ends of the lower bottom plate (1-2), and the opening direction of the waist hole II (1-2-1) is consistent with the width direction of the lower bottom plate (1-2); the waist hole I (1-1-1) and the waist hole II (1-2-1) are arranged opposite to each other up and down, the grounding bolt (1-4) passes through the waist hole I (1-1-1) and the waist hole II (1-2-1) in sequence and is anchored in the ground, and the two lifting handles (1-6) are respectively installed at the two ends of the upper top plate (1-1).

2. A bending-torsional buckling test system for rectangular tube flange curved composite beams according to claim 1, characterized in that: Each steel column (2) comprises two side plates (2-1), a connecting web II (2-2), an upper cover plate (2-3), a lower cover plate (2-4), a plurality of stiffening ribs II (2-5) and a plurality of triangular stiffening ribs (2-6); the two side plates (2-1) are arranged opposite to each other in the transverse direction and are fixedly connected to the plurality of stiffening ribs II (2-5) through the connecting web II (2-2); the upper cover plate (2-3) is fixed to the top ends of the two side plates (2-1), the lower cover plate (2-4) is fixed to the bottom ends of the two side plates (2-1), and the plurality of triangular stiffening ribs (2-6) are respectively connected between the side plates (2-1) and the lower cover plate (2-4) and between the connecting web II (2-2) and the lower cover plate (2-4).

3. The bending-torsional buckling test system of rectangular tube flange curved composite beam according to claim 2, characterized in that: The upper crossbeam (3) is an I-beam, and the two ends of the upper crossbeam (3) are connected to the upper sealing plates (2-3) of the two steel columns (2) through the bottom plate on the upper crossbeam (3) and a plurality of bolts.

4. The bending-torsional buckling test system of rectangular tube flange curved composite beam according to claim 3, characterized in that: The support (4) comprises a support base (4-1) and a cylindrical steel (4-2), wherein the support base (4-1) is placed on the upper top plate (1-1) of the support base (1); the cylindrical steel (4-2) in one of the support devices (A) is radially placed above the support base (4-1), and the cylindrical steel (4-2) in the other support device (A) is radially welded above the support base (4-1); the axial direction of the cylindrical steel (4-2) is arranged toward the direction of the steel column (2), and the end of the test beam (C) is placed on the cylindrical steel (4-2).

5. The bending-torsional buckling test system of rectangular tube flange curved composite beam according to claim 4, characterized in that: The vertical limiting mechanism (5) comprises an internally threaded sleeve (5-1), a stud (5-2) and an elastic gasket (5-3); one end of the internally threaded sleeve (5-1) is installed on the lower surface of the upper crossbeam (3), one end of the stud (5-2) is screwed to the other end of the internally threaded sleeve (5-1), and the elastic gasket (5-3) is installed on the other end of the stud (5-2).

6. The bending-torsional buckling test system of rectangular tube flange curved composite beam according to claim 5, characterized in that: Each set of lateral limiting mechanisms (6) comprises two limiting support assemblies, and the two limiting support assemblies are respectively mounted on two steel columns (2) in a relative manner; each limiting support assembly comprises two support plates (6-1), a bearing support (6-2), a cylindrical roller bearing (6-3), four connecting bolts (6-4) and four adjusting screws (6-5); the two support plates (6-1) are respectively arranged on both sides of the steel column (2) and are fixedly connected by the four connecting bolts (6-4); the support plate (6-1) located on the outer side of the steel column (2) abuts against the outer side of the steel column (2), and the four adjusting screws (6-5) are fixedly connected to the outer side of the steel column (2). The bearing support (6-2) is fixedly connected to the support plate (6-1) on the inner side of the steel column (2), and the cylindrical roller bearing (6-3) is installed in the bearing support (6-2). The connecting line direction of the cylindrical roller bearings (6-3) of each set of lateral limiting mechanisms (6) is perpendicular to the tangent direction of the test beam (C) at this location, and the outer circumferential surface of the cylindrical roller bearing (6-3) is in contact with the upper flange or the lower flange of the test beam (C).

7. The bending-torsion buckling test system of rectangular tube flange curved composite beam according to claim 6, characterized in that: The vertical loading device (B) comprises a supporting crossbeam (7), a jack (8) and a knife hinge support (9); the supporting crossbeam (7) is arranged between the two supporting devices (A) and is located above the test beam (C); the fixed end of the jack (8) is installed on the supporting crossbeam (7) and can move along the extension direction of the supporting crossbeam (7); the knife hinge support (9) is placed at the top end of the middle position of the test beam (C), and the telescopic end of the jack (8) abuts against the upper end surface of the knife hinge support (9).

8. The bending-torsional buckling test system of rectangular tube flange curved composite beam according to claim 7, characterized in that: The knife hinge support (9) comprises an upper steel plate (9-1) and a lower steel plate (9-2), and the middle positions of the upper steel plate (9-1) and the lower steel plate (9-2) are hingedly connected.

9. A test method for the bending-torsion buckling test system of rectangular tube flange curved composite beams as claimed in claim 8, characterized in that: The specific test process is as follows: Step 1, according to the size of the central angle of the test beam (C), the positions of the two support bases (1) are adjusted within a certain range while the grounding bolts (1-4) are fixed; Step 2, placing the two ends of the test beam (C) on the cylindrical steels (4-2) in the two support bases (1), respectively, adjusting the position of the test beam (C) so that the support base (1) is arranged perpendicular to the tangent direction of the end of the test beam (C), ensuring that the lateral limiting mechanisms (6) on both sides of the test beam (C) are in contact with the test beam (C) at corresponding points; Step 3, screw down the stud (5-2) in the vertical limiting mechanism (5) so that the stud (5-2) extends out of the internal threaded sleeve (5-1), and the elastic gasket (5-3) on the stud (5-2) presses against the upper flange of the test beam (C), so as to prevent the upper flange and the web at the end of the test beam (C) from twisting relative to each other; Step 4, the upper flange and the lower flange of the test beam (C) are clamped by two sets of lateral limiting mechanisms (6) arranged above and below, respectively, so that the two end portions of the test beam (C) are integrally lateral limited by the two sets of lateral limiting mechanisms (6); Step 5, place the knife hinge support (9) at the top of the middle position of the test beam (C), the telescopic column of the jack (8) extends out and presses on the upper steel plate (9-1) of the knife hinge support (9), as the load force of the jack (8) increases, the jack (8) slides along the supporting beam (7) toward the bending and torsion direction of the test beam (C), the loading end of the jack (8) always abuts against the upper steel plate (9-1), wherein the upper steel plate (9-1) is always in a horizontal state, and the lower steel plate (9-2) flips with the inclination of the upper flange of the test beam (C), so that the jack (8) always applies load to the loading point of the test beam (C).

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