Testing device for simulating transverse constraint of stirrup on longitudinal bar

Abstract

The utility model provides a test device for simulating transverse constraint of a stirrup on a longitudinal bar. The test device comprises a cross beam, a vertical stand column, two telescopic transverse supporting long rods with scales and two dial indicator devices. The transverse beam support and the two transverse supporting long rods are arranged to provide support for simulating stirrup constraint for the vertical reinforcing steel bars, and compared with the mode that the reinforcing steel bar beam end is clamped through a clamp and then loaded, the state of the longitudinal reinforcing steel bars in an actual reinforced concrete column during vertical stress can be simulated more accurately; due to the arrangement of the dial indicator, the total transverse deflection at the beginning of buckling can be calculated; when the total transverse deflection limit value exceeds the limit value Dt, l is equal to 0.7 mm, it can be judged that the reinforcing steel bars start to bend even if the sudden deflection increasing point is not observed; and effective data support is provided for judging the compressive buckling of the reinforcing steel bar.

Description

Technical Field

[0001] The present invention relates to a test device for simulating the lateral restraint of longitudinal bars by stirrups. Background Art

[0002] When reinforced concrete (RC) beam and column members are subjected to earthquake actions, the longitudinal bars may undergo compressive buckling, leading to the failure of the RC members and further causing the collapse of the structure. Currently, existing test devices usually use clamps to hold both ends of the bars and apply axial pressure to simulate the compressive buckling behavior of the longitudinal bars. However, due to the high stiffness of the vertical clamps, which does not conform to the lateral restraint conditions of the longitudinal bars by stirrups in actual RC members, it is impossible to accurately simulate the stirrup restraint on the longitudinal bars. Therefore, the compressive buckling behavior of the bars cannot be accurately evaluated through test data. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a test device for simulating the lateral restraint of longitudinal bars by stirrups to solve the above problems.

[0004] The present invention adopts the following solutions:

[0005] The present application provides a test device for simulating the lateral restraint of longitudinal bars by stirrups, including a cross beam, a vertical column, two horizontally supporting long rods with scales and telescopic functions, and two dial gauge devices;

[0006] The vertical column is installed in the middle of the cross beam; both ends of the cross beam are used for being movably fixed to an MTS testing machine; the two horizontally supporting long rods with scales and telescopic functions are symmetrically arranged along the cross beam, one end of which is provided with a first fixing connector and is respectively movably connected to the upper and lower parts of the vertical column, and the other end is movably provided with a second fixing connector for adapting to steel bars of different sizes;

[0007] The dial gauge device includes a seat body, a first rotating rod, a second rotating rod, a base, and a dial gauge arranged on the cross beam; a first rotating socket is provided on the seat body; one end of the first rotating rod is provided with a first ball head adapted to the first rotating socket, and the other end is provided with a second rotating socket; one end of the second rotating rod is provided with a second ball head adapted to the second rotating socket, and the other end is provided with a third rotating socket; one side of the base is provided with a third ball head adapted to the third rotating socket; the dial gauge is arranged on the other side of the base;

[0008] The measuring heads of the two dial gauges are used to measure the deflections in the orthogonal directions at the middle position of the steel bar.

[0009] Further, the second fixing connector can adapt to steel bars with a diameter of 12 - 25 mm.

[0010] Further, a through hole for connecting the vertical column is provided in the middle of the cross beam.

[0011] Further, enclosed fixing parts are provided at both ends of the cross beam and fastened by bolts to connect the support columns on the MTS testing machine.

[0012] Further, the first fixed connecting piece is an enclosed fixing piece and is fastened by bolts.

[0013] Further, the center distance between the two transverse support long bars is the spacing of the stirrups.

[0014] Further, the distances between the two transverse support long bars and the upper and lower clamps on the loading device are respectively 1 / 2 of the center distance of the transverse support long bars.

[0015] By adopting the above technical solutions, the following technical effects can be achieved by the present invention:

[0016] 1. By providing a cross beam support and two transverse support long bars to provide support for simulating stirrup constraints for vertical steel bars, compared with the method of only clamping the steel bar beam ends with clamps and then loading, the state of the longitudinal steel bars in actual reinforced concrete columns under vertical stress can be simulated more accurately.

[0017] 2. The cross beam can be movably fixed on the two transverse columns of the MTS testing machine and can be movably set at the position required for test loading; at the same time, the distance between the two transverse long straight bars can be flexibly adjusted according to the spacing of different stirrups; the movably set fixed connecting piece can adapt to steel bars of different sizes.

[0018] 3. The deflections of the steel bar in the orthogonal directions are measured by two dial gauges. By calculating the transverse deflection Dr in the direction of the longitudinal rib and the transverse deflection D0 in the direction orthogonal to the longitudinal rib at the middle height of the steel bar specimen at each moment obtained by test measurement through the vector synthesis method, the total transverse deflection Dt after the buckling of the steel bar can be obtained. The measurement results of multiple single steel bar cyclic loading tests and the bending degree that can be recognized by the human eye are used to approximately estimate the limit value Dt,lim of the total transverse deflection at the beginning of buckling as 0.7 mm, that is, when the limit value of the total transverse deflection exceeds this limit value, even if no sudden increase point of the deflection is observed, it can be judged that the steel bar begins to buckle. It provides effective data support for judging the compression buckling of the steel bar. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0020] Figure 1 It is a schematic structural diagram of a test device for simulating the lateral restraint of longitudinal bars by stirrups according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic structural diagram of a support long rod of a test device for simulating the lateral restraint of longitudinal bars by stirrups according to an embodiment of the present invention;

[0022] Figure 3 It is a schematic structural diagram of a cross beam of a test device for simulating the lateral restraint of longitudinal bars by stirrups according to an embodiment of the present invention;

[0023] Figure 4 It is a schematic structural diagram of a dial indicator of a test device for simulating the lateral restraint of longitudinal bars by stirrups according to an embodiment of the present invention;

[0024] Figure 5 It is a three - dimensional structural diagram of a test device for simulating the lateral restraint of longitudinal bars by stirrups when applied to the loading of an MTS instrument in a laboratory according to an embodiment of the present invention;

[0025] Icon: vertical column 1, support long rod 2, cross beam 3, steel bar 4, dial indicator device 5, first bolt 21, first fixing connector 22, first long straight rod 23, fixing knob 24, second fixing connector 25, second long straight rod 26, second bolt 31, fixing part 32, through hole 33, seat body 51, first rotating rod 52, second rotating rod 53, base 54, dial indicator 55, first ball head 56, second ball head 57, MTS testing machine 6, test device 7. Detailed implementation manners

[0026] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] Embodiment

[0028] Combined with Figures 1 to 5As shown in the figure, this embodiment provides a test device 7 for simulating the lateral restraint of longitudinal bars by stirrups, including a cross beam 3, a vertical column 1, two horizontally support long rods 2 with scales and telescopic functions, and two dial gauge devices 5;

[0029] The vertical column 1 is installed in the middle of the cross beam 3; both ends of the cross beam 3 are used for movably fixing to the MTS testing machine 6; the two horizontally support long rods 2 with scales and telescopic functions are symmetrically arranged along the cross beam 3, one end of which is provided with a first fixing connector 22, which is respectively movably connected to the upper and lower parts of the vertical column 1, and the other end is detachably provided with a second fixing connector 25 through threads for adapting to steel bars 4 of different sizes;

[0030] The dial gauge device 5 includes a seat body 51 arranged on the cross beam 3, a first rotating rod 52, a second rotating rod 53, a base 54 and a dial gauge 55; a first rotating socket is arranged on the seat body 51; one end of the first rotating rod 52 is provided with a first ball head 56 adapted to the first rotating socket, and the other end is provided with a second rotating socket; one end of the second rotating rod 53 is provided with a second ball head 57 adapted to the second rotating socket, and the other end is provided with a third rotating socket; a third ball head is arranged on one side of the base 54 and adapted to the third rotating socket; the dial gauge 55 is arranged on the other side of the base 54;

[0031] The measuring heads of the two dial gauges 55 are used to measure the deflections in the orthogonal directions at the middle position of the steel bar 4. Specifically, in this embodiment, as Figure 3 、 Figure 4 and Figure 5 shown, a through hole 33 for connecting the vertical column 11 is arranged in the middle of the cross beam 3; both ends of the cross beam 3 are provided with surrounding fixing parts 32 and fastened by second bolts 31 to connect the support columns on the MTS testing machine 6. Through the surrounding fixing parts 32 and fastening by the second bolts 31, the height position required for test loading can be movably set.

[0032] The two dial gauge devices 5 for measuring the deflections in the orthogonal directions at the middle position of the steel bar 4 can achieve large-range three-dimensional rotation through the arrangement of multiple rotating rods, rotating sockets and ball heads, so as to place the two dial gauges 55 in the orthogonal directions at the middle position of the steel bar 4.

[0033] The horizontally support long rod 2 includes a first long straight rod 23 and a second long straight rod 26 that are sleeved with each other and fixed by a fixing knob 24, and the two long straight rods are provided with scales. The two horizontally support long rods 2 with scales and telescopic functions are symmetrically arranged along the cross beam 3, as Figure 1 and Figure 2As shown in the figure, the first fixing connector 22 at one end of the supporting long rod 2 is an enclosed fixing part, and is fastened by the first bolt 21. In this way, the distance between the two supporting long rods 2 can be flexibly adjusted according to the spacing of different stirrups. The second fixing connector 25 at the other end of the supporting long rod 2 is also an enclosed fixing part, and is fastened by bolts. Moreover, it is detachably arranged at the other end of the supporting long rod 2 through threaded connection, and can be adapted to steel bars 4 with a diameter of 12 - 25 mm.

[0034] By providing a cross beam 3 for support and two horizontally supporting long rods 2 with scales and being telescopic to provide support for simulating the stirrup constraint for the vertical steel bar 4, compared with the method of only clamping the steel bar 4 at the beam end with a fixture and then applying load, the state of the actual vertical force on the reinforced concrete column can be simulated more accurately, so that the compressive buckling behavior of the steel bar 4 can be evaluated more accurately through test data.

[0035] The cross beam 3 can be movably fixed on two horizontal columns of the MTS testing machine 6 and can be movably set at the position required for the test loading; at the same time, the distance between the two horizontally supporting long rods 2 with scales and being telescopic can be flexibly adjusted according to the spacing of different stirrups; the movably arranged fixing connectors can be adapted to steel bars 4 of different sizes.

[0036] The following specifically describes the steps of conducting an experiment using the described test device:

[0037] S1: Determine the height of the MTS testing machine 6 from the ground, and fix the left and right ends of the cross beam 3 to the MTS testing machine 6 at the required height.

[0038] S2: Measure the central distance from the cross beam 3 to the steel bar 4 to be tested, and adjust the scale to the appropriate supporting long rod 2.

[0039] S3: Determine the distance between the two supporting long rods 2 according to the required stirrup spacing, and fix them on the vertical column 1.

[0040] S4: Select the fixing connector according to the diameter of the steel bar 4 to be tested, and fix the steel bar 4 to be tested to the second fixing connector 25.

[0041] S5: Adjust the two dial gauge devices 5 to the middle position of the steel bar 4 in the direction orthogonal to its longitudinal rib for measuring the deflection of the longitudinal rib at the middle position of the steel bar 4 in the direction orthogonal to it.

[0042] S6: Start the MTS testing machine 6 to apply axial pressure to the steel bar 4 to be tested, and record the test data.

[0043] The deflections of the steel bar 4 in the orthogonal directions are measured by two dial gauges 55. For the transverse deflection Dr in the direction of the longitudinal rib and the transverse deflection D0 in the direction orthogonal to the longitudinal rib at the middle height of the steel bar 4 specimen measured in the test at each moment, calculations are carried out through the vector synthesis method, and the total transverse deflection Dt after the buckling of the steel bar 4 can be obtained. The measurement results of multiple single steel bar 4 cyclic loading tests and the bending degree recognizable by the human eye are used to approximately estimate the limit value Dt,lim = 0.7 mm of the total transverse deflection at the beginning of buckling, that is, when the limit value of the total transverse deflection exceeds this limit value, even if no sudden increase point of the deflection is observed, it can be judged that the steel bar 4 starts to buckle; this provides effective data support for judging the compression buckling of the steel bar 4.

[0044] Through the application of the test device 7 that simulates the transverse restraint of the stirrups on the longitudinal bars, the test method can more accurately simulate the state of the longitudinal stressed steel bars 4 in the actual reinforced concrete members when they are stressed; thus, the compression buckling behavior of the steel bars 4 can be more accurately evaluated through the test data.

[0045] The above is only the preferred implementation manner of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0047] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0048] In the present invention, unless otherwise clearly defined or limited, terms such as "installed", "connected", "linked", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication between two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] In the present invention, unless otherwise clearly defined or limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

Claims

1. An experimental device for simulating the transverse constraint of stirrups on longitudinal bars, characterized in that It includes a cross beam, a vertical column, two horizontally supporting telescopic long rods with scales, and two dial indicator devices; The vertical column is installed in the middle of the cross beam; both ends of the cross beam are used to be movably fixed to an MTS testing machine; the two horizontally supporting telescopic long rods with scales are symmetrically arranged along the cross beam, one end of which is provided with a first fixing connector and is respectively movably connected to the upper and lower parts of the vertical column, and the other end is detachably provided with a second fixing connector through threads for adapting to steel bars of different sizes; The dial indicator device includes a seat body arranged on the cross beam, a first rotating rod, a second rotating rod, a base and a dial indicator; a first rotating socket is arranged on the seat body; one end of the first rotating rod is provided with a first ball head adapted to the first rotating socket, and the other end is provided with a second rotating socket; one end of the second rotating rod is provided with a second ball head adapted to the second rotating socket, and the other end is provided with a third rotating socket; a third ball head is arranged on one side of the base and is adapted to the third rotating socket; the dial indicator is arranged on the other side of the base; The measuring heads of the two dial indicators are used to measure the deflections in the orthogonal directions at the middle position of the steel bar.

2. The test device for simulating the lateral restraint of longitudinal bars by stirrups according to claim 1, wherein The second fixing connector can be adapted to steel bars with a diameter of 12 - 25 mm.

3. The test device for simulating the lateral restraint of longitudinal bars by stirrups according to claim 1, characterized in that, A through hole for connecting the vertical column is arranged in the middle of the cross beam.

4. The test device for simulating the lateral restraint of longitudinal bars by stirrups according to claim 1, characterized in that Both ends of the cross beam are provided with surrounding fixing parts and are fastened by bolts to connect the support columns on the MTS testing machine.

5. The test device for simulating the lateral restraint of longitudinal bars by stirrups according to claim 1, characterized in that, The first fixing connector is a surrounding fixing piece and is fastened by bolts.

6. The test device for simulating the lateral restraint of longitudinal bars by stirrups according to claim 1, characterized in that, The center distance between the two horizontally supporting long rods is the spacing of the stirrups.

7. The test device for simulating the lateral restraint of longitudinal bars by stirrups according to claim 1, characterized in that, The distances between the two horizontally supporting long rods and the upper and lower clamps in the loading device are respectively 1 / 2 of the center distance between the horizontally supporting long rods.

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