Existing brick masonry structure rigidity eccentric quasi-static force loading device and testing method

Abstract

The invention discloses an eccentric quasi-static loading device for the structural rigidity of an existing brick masonry and a testing method, and relates to the technical field of quasi-static loading testing of the brick masonry, the eccentric quasi-static loading device comprises a loading pedestal, a loading assembly is arranged above the loading pedestal, a load distribution assembly is arranged above the loading assembly, and the loading assembly is connected with the loading pedestal. The reaction walls are arranged at the two ends of the load distribution assembly and the two ends of the loading assembly, the loading assembly is connected with the reaction wall on one side, the portal is arranged between the reaction walls on the two sides, and the portal is connected with the load distribution assembly. By the adoption of the existing brick masonry structure rigidity eccentric pseudo-static loading device and the testing method, the authenticity of the load condition in the simulated wall pseudo-static test process in the test is guaranteed, the vertical load loading position is adjusted and refined, the load applying mode is optimized, the loading device is adjusted, and the test efficiency is improved. The influence of a vertical load on a horizontal dynamic load is reduced, and the overall precision of the test is improved.

Description

Technical Field

[0001] The invention relates to the technical field of brick masonry quasi-static loading test, and in particular to an eccentric quasi-static loading device and a test method for the rigidity of an existing brick masonry structure. Background Art

[0002] Due to the age of masonry structures, no corresponding earthquake-resistant measures were taken when these buildings were built. When a moderate or strong earthquake occurs, masonry structures often suffer serious damage due to poor earthquake resistance. Under the action of earthquake loads, masonry walls may be subjected to in-plane loads (bending or shear), out-of-plane loads (bending), and the combined effects of the two. The quasi-static test of masonry walls can effectively evaluate the seismic performance of masonry structures, observe the failure process of masonry walls, and analyze the failure characteristics.

[0003] In view of the need of quasi-static test loading, in the normal test process, the commonly used loading method is usually just to simply stack the distribution beam and the loading beam, and directly apply the vertical load on the distribution beam. This loading method can only imitate the arrangement of the vertical uniformly distributed load. In the actual practical process, the masonry wall at different positions is subjected to different vertical loads, and the vertical loads of the masonry walls in different areas are not evenly arranged at the centroid position of the masonry wall. It is difficult for the existing loading device to accurately evaluate the performance of the masonry wall under the non-uniformly distributed load. In addition, in the existing loading device, the vertical load applied by the jack is directly transmitted to the loading beam through hard contact. When the horizontal actuator applies the horizontal load, the friction between the loading beams under the action of the vertical load is large, which has a great influence on the application of the horizontal actuating force of the test, thereby affecting the overall accuracy of the test.

[0004] The existing specimen fixing bottom beam often only fixes the specimen in the bottom beam through the simple blocking effect of the concrete protrusions on the left and right sides, which is difficult to truly simulate the embedded mutual constraint between the masonry wall and the foundation. During the application of horizontal force, the pseudo-static masonry specimen and the pedestal are also prone to bottom displacement due to the small constraint between the bottom and the pedestal, which affects the test results and causes the specimen as a whole to form horizontal shear failure along the weak area at the root of the reinforced wall, making it difficult to truly simulate the "X"-shaped shear failure of the wall under the action of an earthquake. Summary of the invention

[0005] The purpose of the present invention is to provide an eccentric quasi-static loading device and a testing method for the stiffness of an existing brick masonry structure, so as to solve the problems raised in the above-mentioned background technology. By strengthening the bottom constraint of the specimen, adjusting the application method of the vertical load, and designing the method of the interlayer rolling shaft, the accuracy and operation effect of the specimen can be effectively improved. In the actual loading process, the vertical loads at different positions can be reasonably adjusted according to the needs of the test simulation, while avoiding the influence of the horizontal friction force generated by the large vertical load on the horizontal load, thereby improving the operability of the test.

[0006] To achieve the above-mentioned purpose, the present invention provides an eccentric quasi-static loading device for the stiffness of an existing brick masonry structure, including a loading pedestal, a loading assembly is arranged above the loading pedestal, a load distribution assembly is arranged above the loading assembly, reaction walls are arranged at both ends of the load distribution assembly and the loading assembly, and the loading assembly is connected to the reaction wall on one side, a portal is arranged between the reaction walls on both sides, and the portal is connected to the load distribution assembly.

[0007] Preferably, the load distribution assembly includes a jack arranged below the gantry, a load distribution beam is arranged below the jack, a toothed pad is arranged below the load distribution beam, and a plurality of latch teeth are arranged on the toothed pad;

[0008] A single-column tooth is fixedly provided at the bottom of the load distribution beam, and the single-column tooth is meshed with the teeth. By making the single-column tooth mesh with the teeth at different positions, the out-of-plane loading position of the vertical load applied by the jack on the masonry wall specimen is adjusted to achieve eccentric quasi-static loading.

[0009] Preferably, the jack and the load distribution beam are slidably connected via a slide rail and a slider. The slider is arranged at the bottom of the jack, and the slide rail is arranged at the top of the load distribution beam. By adjusting the position of the slider on the slide rail, the in-plane loading position of the vertical load applied by the jack on the masonry wall specimen is adjusted to achieve eccentric quasi-static loading.

[0010] Preferably, the jack and the gantry are connected via a plurality of rolling shafts and a steel support pad, the steel support pad is arranged on the top of the jack, and the plurality of rolling shafts are arranged between the steel support pad and the gantry.

[0011] Preferably, the loading assembly comprises a loading beam disposed below the toothed pad, a masonry wall specimen is disposed below the loading beam, and a lower portion of the masonry wall specimen is disposed in a groove of the bottom beam;

[0012] One end of the loading beam is connected with a horizontal actuator, and the horizontal actuator is connected with a reaction wall on one side.

[0013] Preferably, lifting rings are symmetrically arranged on both sides of the bottom beam, and the bottom beam is fixed to the loading platform by fixing bolts.

[0014] Preferably, a first displacement meter is provided on the masonry wall specimen, a second displacement meter is provided on the bottom beam, and a third displacement meter is provided on the loading beam.

[0015] A method for testing the stiffness of an existing brick masonry structure using an eccentric quasi-static loading device, comprising the following steps:

[0016] Step S1, casting the test piece: during use, first design and manufacture a bottom beam with a groove, after the concrete material of the bottom beam reaches the design strength, build a masonry wall test piece in the groove of the bottom beam by masonry bricks, the casting height of the masonry wall test piece is set to 800-1400 mm, the width is set to 1000-1500 mm, during the masonry process, the wall surface of the masonry wall test piece is made flat, the top plane is horizontal, and the wall width of the masonry wall test piece is set between 200-300 mm;

[0017] Step S2, fixing the test piece: after the concrete material of the masonry wall test piece reaches its design strength, the masonry wall test piece is moved to the loading position through the lifting ring, and the bottom beam is fixed to the loading pedestal through the fixing bolts, and then the rolling shaft and the steel support pad are pre-tied to the door frame through the steel wire rope;

[0018] Step S3, arranging the loading device: hoisting and fixing the loading beam and the horizontal actuator, placing a toothed pad on the loading beam, determining the corresponding tooth position on the toothed pad according to the designed loading point position, placing the load distribution beam so that the single column tooth and the corresponding tooth are meshed, determining the loading position of the jack in the plane according to the in-plane eccentric loading design requirements and arranging it between the steel support pad and the load distribution beam, fixing the position of the jack and the steel support pad by bolts, and removing the steel wire rope between the steel support pad and the fixed gantry;

[0019] Step S4: Perform quasi-static test loading according to design requirements.

[0020] Therefore, the present invention adopts the above-mentioned eccentric pseudo-static loading device and test method for the stiffness of existing brick masonry structures, which has the following beneficial effects:

[0021] (1) The device uses a load distribution beam with a slide rail at the vertical load position to provide a non-uniform load, simulating the vertical load conditions of the masonry wall during actual use. At the same time, the dimensions of the various structural components of the load distribution beam are optimized. During use, it is ensured that the load distribution beam has sufficient rigidity and does not produce bending deformation.

[0022] (2) The device arranges a toothed pad under the load distribution beam, and fixes the vertical loading point by interlocking the column teeth during loading.

[0023] (3) This device uses an improved bottom beam with a groove as the lower fixed node to ensure the fixed constraint effect of the masonry wall specimen during loading and prevent the bottom of the masonry wall specimen from shifting and causing damage during loading.

[0024] (4) This device uses a rolling shaft as a vertical load transfer device, which effectively avoids the friction caused by the vertical load affecting the data monitoring of the horizontal force loading device. The rolling shaft contacts the jack through a steel support plate, and the rolling shaft is in direct contact with the steel gantry. The rolling shafts are arranged in parallel, and no torsional collision occurs during the horizontal rolling process.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of an embodiment of an eccentric quasi-static loading device and a testing method for the stiffness of an existing brick masonry structure according to the present invention;

[0027] Figure 2 It is a layout diagram of a load distribution component and a loading component of an existing brick masonry structure stiffness eccentric pseudo-static loading device and a testing method of the present invention;

[0028] Figure 3 It is a top view of the bottom beam of an existing brick masonry structure stiffness eccentric pseudo-static loading device and testing method of the present invention;

[0029] Figure 4 It is a structural schematic diagram of a load distribution component of an existing brick masonry structure stiffness eccentric pseudo-static loading device and a test method according to the present invention;

[0030] Figure 5 It is a side view of a load distribution component of an existing brick masonry structure stiffness eccentric pseudo-static loading device and a test method of the present invention;

[0031] Figure 6 It is a schematic diagram of the loading end arrangement of an existing brick masonry structure stiffness eccentric pseudo-static loading device and a testing method of the present invention;

[0032] Figure numerals: 1. loading pedestal; 2. loading assembly; 21. loading beam; 22. masonry wall specimen; 23. bottom beam; 231. lifting ring; 232. fixing bolt; 24. groove; 25. horizontal actuator; 3. load distribution assembly; 31. jack; 32. load distribution beam; 33. toothed pad; 34. rolling shaft; 35. steel support pad; 36. slide rail; 37. slider; 38. single column tooth; 4. reaction wall; 5. portal; 6. first displacement meter; 7. second displacement meter; 8. third displacement meter. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] Example

[0036] See also Figure 1-6 The present invention provides an eccentric quasi-static loading device for the stiffness of an existing brick masonry structure, comprising a loading pedestal 1, a loading assembly 2 is arranged above the loading pedestal 1, a load distribution assembly 3 is arranged above the loading assembly 2, reaction walls 4 are arranged at both ends of the load distribution assembly 3 and the loading assembly 2, and the loading assembly 2 is connected to the reaction wall 4 on one side, a door frame 5 is arranged between the reaction walls 4 on both sides, and the door frame 5 is connected to the load distribution assembly 3.

[0037] The load distribution assembly 3 includes a jack 31 arranged below the gantry, a load distribution beam 32 is arranged below the jack 31, and a toothed pad 33 is arranged below the load distribution beam 32. The diameter of the teeth of the toothed pad 33 is controlled to be 50-120 mm, and the spacing is controlled to be 25-80 mm. The teeth are connected to the toothed pad 33 by welding. The toothed pad 33 is made of a steel plate with a thickness of 15-40 mm, a width of 300-500 mm, and a length of 1000-2000 mm. By setting the toothed pad 33, the position of the loading point can be adjusted according to the design requirements before the pseudo-static test loading, so as to simulate the actual vertical load distribution of the masonry wall specimen 22, and provide an important test method for simulating the actual masonry wall stress process.

[0038] The jack 31 and the gantry 5 are connected by a plurality of rolling shafts 34 and a steel support pad 35. The thickness of the steel support pad 35 should be controlled at 10-50 mm, the width is 200-500 mm, and the length is 800-1500 mm. The steel support pad 35 is arranged on the top of the jack 31, and a plurality of rolling shafts 34 are arranged between the steel support pad 35 and the gantry 5. The rolling shaft 34 is in direct contact with the gantry 5, and the surface should be smooth to avoid grooves and protrusions. Each steel roller should be arranged in parallel. In the process of horizontal rolling, no torsion collision should occur. The spacing between the rolling shafts 34 should be controlled at 100-200 mm, the diameter of the rolling shaft 34 should be controlled at 10-50 mm, and the length should be flush with the width of the steel support pad 35. By providing a rolling shaft 34 at the support of the jack 31, effective support can be provided for the vertical load, and the influence of the vertical friction of the load distribution component 3 on the horizontal force can be reduced, thereby improving the authenticity and reliability of the quasi-static test.

[0039] The jack 31 and the load distribution beam 32 are slidably connected via a slide rail 36 and a slider 37. The slider 37 is arranged at the bottom of the jack 31, and the slide rail 36 is arranged at the top of the load distribution beam 32. By adjusting the position of the slider 37 on the slide rail 36, the in-plane loading position of the vertical load applied by the jack 31 on the masonry wall specimen 22 is adjusted to achieve eccentric quasi-static loading. The width of the slide rail 36 is controlled to be 40-200 mm, the height is 20-60 mm, the length of the load distribution beam 32 should be 800-2500 mm, the thickness of the steel plate of the load distribution beam 32 is 20-50 mm, each meter of the load distribution beam 32 should have at least six sections of beam ribs, the beam rib spacing is 200-500 mm, the height of the load distribution beam 32 is 200-600 mm, and a semicircular cross-section single column clamping tooth 38 is arranged on the lower side. A single distribution beam is welded with a single column clamping tooth 38, and the diameter of the single column clamping tooth 38 is controlled to be 40-120 mm, which runs through the entire length direction of the load distribution beam 32. During use, it is ensured that the load distribution beam 32 has sufficient rigidity and will not bend or deform.

[0040] A single-column tooth 38 is fixedly provided at the bottom of the load distribution beam 32, and the single-column tooth 38 meshes with the tooth of the toothed pad 33. By meshing the single-column tooth 38 with the teeth at different positions, the out-of-plane loading position of the vertical load applied by the jack 31 on the masonry wall specimen 22 is adjusted to achieve eccentric quasi-static loading. The out-of-plane eccentric loading position of the vertical load on the masonry wall specimen 22 is adjusted by the toothed pad 33 and the single-column tooth 38. By controlling the out-of-plane eccentric position, the effects of different loading modes such as the centroidal axial load and the stiffness center axial load are compared. At the same time, the arrangement of the single-column tooth 38 can effectively prevent the loading point offset caused by the overall deformation of the specimen at the end of the vertical load during loading.

[0041] This device adopts the connection mode of the slide rail 36 and the slider 37 and the connection mode of the single column clamping tooth 38 and the toothed pad 33. Before the pseudo-static test loading, the horizontal and front-back positions of the jack 31 in the test can be adjusted according to the test design requirements to simulate the uneven arrangement of the vertical load on the masonry wall specimen 22 in the plane, reflect the unevenness of the vertical load on the masonry wall specimen 22 under real conditions, simulate the eccentric loading effect of the vertical load on the masonry wall specimen 22 in the actual use process, and ensure the adjustability of the application position of the vertical load during the test.

[0042] The loading assembly 2 includes a loading beam 21 disposed below the toothed pad 33, one end of the loading beam 21 is connected to a horizontal actuator 25, and the horizontal actuator 25 is connected to a side reaction wall 4. A masonry wall specimen 22 is disposed below the loading beam 21, and the lower part of the masonry wall specimen 22 is disposed in a groove 24 of the bottom beam 23. The wall thickness of the groove 24 should be controlled between 30 and 100 mm, and ribbed steel bars are configured to ensure the overall strength and rigidity of the bottom beam 23. In order to ensure the fixing effect between the masonry wall specimen 22, the bottom beam 23 and the foundation, and to ensure the stability of the masonry wall specimen 22 during the loading test, on the basis of the connection between the masonry wall specimen 22 and the bottom beam 23, a rectangular groove 24 is opened at the center of the bottom beam 23. During the pouring of the masonry wall specimen 22, the first layer of masonry is poured in the groove 24 in advance, and then the masonry wall specimen 22 is gradually poured upward. In this process, the peripheral part of the masonry wall specimen 22 in the groove 24 is cast and fixed with concrete to ensure the stability of the connection between the masonry wall specimen 22 and the loading platform 1, and effectively ensure the simulation effect of the destruction process of the real masonry wall specimen 22 during the test.

[0043] The bottom beam 23 is symmetrically provided with lifting rings 231 on both sides, and the bottom beam 23 is fixed to the loading platform 1 by fixing bolts 232. The shortest distance between the position of the lifting ring 231 and the outer side of the masonry wall specimen 22 should be controlled within 50 to 200 mm to avoid collision and damage of the masonry wall specimen 22 by the lifting rope during the lifting process of the masonry wall specimen 22. During the fixed installation of the bottom beam 23, the diameter of the fixing bolts 232 and the corresponding holes is 50 to 150 mm to provide sufficient connection capacity. The position of the fixing bolts 232 should be tight enough and a rigid gasket should be configured to avoid the lifting and sliding of the bottom beam 23 during the loading process. The top surface of the bottom beam 23 coincides with the plane between the brick layers of the masonry wall specimen 22.

[0044] A first displacement meter 6 is provided on the masonry wall specimen 22 , a second displacement meter 7 is provided on the bottom beam 23 , and a third displacement meter 8 is provided on the loading beam 21 .

[0045] The testing method of the above-mentioned existing brick masonry structure stiffness eccentric pseudo-static loading device comprises the following steps:

[0046] Step S1, casting the test piece: during use, first design and manufacture a bottom beam 23 with a groove 24. After the concrete material of the bottom beam 23 reaches the design strength, build a masonry wall test piece 22 in the groove 24 of the bottom beam 23 by masonry bricks. The casting height of the masonry wall test piece 22 is set to 800-1400 mm, and the width is set to 1000-1500 mm. During the masonry process, the wall surface of the masonry wall test piece 22 is made flat, the top plane is horizontal, and the wall width of the masonry wall test piece 22 is set between 200 and 300 mm.

[0047] Step S2, fixing the test piece: after the concrete material of the masonry wall specimen 22 reaches its design strength, move the masonry wall specimen 22 to the loading position through the lifting ring 231, and fix the bottom beam 23 on the loading platform 1 through the fixing bolts 232, and then pre-tie the rolling shaft 34 and the steel support pad 35 on the door frame 5 through the steel wire rope.

[0048] Step S3, arranging the loading device: hoist and fix the loading beam 21 and the horizontal actuator 25, place the toothed pad 33 on the loading beam 21, determine the corresponding tooth position on the toothed pad 33 according to the designed loading point position, place the load distribution beam 32 so that the single column tooth 38 and the corresponding tooth are engaged, determine the loading position of the jack 31 in the plane according to the in-plane eccentric loading design requirements and arrange it between the steel support pad 35 and the load distribution beam 32, fix the position of the jack 31 and the steel support pad 35 by bolts, and remove the wire rope between the steel support pad 35 and the fixed gantry 5.

[0049] Step S4: Perform quasi-static test loading according to design requirements.

[0050] Therefore, the present invention adopts the above-mentioned eccentric quasi-static loading device and testing method for the stiffness of an existing brick masonry structure, which ensures the authenticity of the load conditions in the quasi-static test process of the wall simulated in the test, adjusts and refines the vertical load loading position, optimizes the load application method, adjusts the loading device, reduces the influence of the vertical load on the horizontal dynamic load, and improves the overall accuracy of the test.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An eccentric pseudo-static loading device for stiffness of existing brick masonry structures, characterized in that: It includes a loading pedestal, a loading assembly is arranged above the loading pedestal, a load distribution assembly is arranged above the loading assembly, reaction walls are arranged at both ends of the load distribution assembly and the loading assembly, and the loading assembly is connected to the reaction wall on one side, a door frame is arranged between the reaction walls on both sides, and the door frame is connected to the load distribution assembly.

2. According to claim 1, an eccentric pseudo-static loading device for stiffness of an existing brick masonry structure is characterized by: The load distribution assembly includes a jack arranged below the gantry, a load distribution beam is arranged below the jack, a toothed pad is arranged below the load distribution beam, and a plurality of latching teeth are arranged on the toothed pad; A single-column tooth is fixedly provided at the bottom of the load distribution beam, and the single-column tooth is meshed with the teeth. By making the single-column tooth mesh with the teeth at different positions, the out-of-plane loading position of the vertical load applied by the jack on the masonry wall specimen is adjusted to achieve eccentric quasi-static loading.

3. The eccentric pseudo-static loading device for stiffness of an existing brick masonry structure according to claim 2, characterized in that: The jack and the load distribution beam are slidably connected by a slide rail and a slider. The slider is set at the bottom of the jack, and the slide rail is set at the top of the load distribution beam. By adjusting the position of the slider on the slide rail, the in-plane loading position of the vertical load applied by the jack on the masonry wall specimen is adjusted to achieve eccentric quasi-static loading.

4. The eccentric pseudo-static loading device for stiffness of an existing brick masonry structure according to claim 3, characterized in that: The jack and the door frame are connected through a plurality of rolling shafts and a steel support pad. The steel support pad is arranged on the top of the jack, and the plurality of rolling shafts are arranged between the steel support pad and the door frame.

5. The eccentric pseudo-static loading device for stiffness of an existing brick masonry structure according to claim 4, characterized in that: The loading assembly comprises a loading beam arranged below the toothed pad, a masonry wall specimen is arranged below the loading beam, and the lower part of the masonry wall specimen is arranged in a groove of the bottom beam; One end of the loading beam is connected with a horizontal actuator, and the horizontal actuator is connected with a reaction wall on one side.

6. The eccentric pseudo-static loading device for stiffness of an existing brick masonry structure according to claim 5, characterized in that: Lifting rings are symmetrically arranged on both sides of the bottom beam, and the bottom beam is fixed on the loading pedestal by fixing bolts.

7. The eccentric pseudo-static loading device for stiffness of an existing brick masonry structure according to claim 6, characterized in that: A first displacement meter is arranged on the masonry wall specimen, a second displacement meter is arranged on the bottom beam, and a third displacement meter is arranged on the loading beam.

8. A method for testing the stiffness of an existing brick masonry structure using the eccentric quasi-static loading device described in claim 7, characterized in that: The following steps are involved: Step S1, casting the test piece: during use, first design and manufacture a bottom beam with a groove, after the concrete material of the bottom beam reaches the design strength, build a masonry wall test piece in the groove of the bottom beam by masonry bricks, the casting height of the masonry wall test piece is set to 800-1400 mm, the width is set to 1000-1500 mm, during the masonry process, the wall surface of the masonry wall test piece is made flat, the top plane is horizontal, and the wall width of the masonry wall test piece is set between 200-300 mm; Step S2, fixing the test piece: after the concrete material of the masonry wall test piece reaches its design strength, the masonry wall test piece is moved to the loading position through the lifting ring, and the bottom beam is fixed to the loading pedestal through the fixing bolts, and then the rolling shaft and the steel support pad are pre-tied to the door frame through the steel wire rope; Step S3, arranging the loading device: hoisting and fixing the loading beam and the horizontal actuator, placing a toothed pad on the loading beam, determining the corresponding tooth position on the toothed pad according to the designed loading point position, placing the load distribution beam so that the single column tooth and the corresponding tooth are meshed, determining the loading position of the jack in the plane according to the in-plane eccentric loading design requirements and arranging it between the steel support pad and the load distribution beam, fixing the position of the jack and the steel support pad by bolts, and removing the steel wire rope between the steel support pad and the fixed gantry; Step S4: Perform quasi-static test loading according to design requirements.

Images