A column fire resistance test loading device under high temperature and test loading method thereof

Abstract

The present invention discloses a column fire resistance test loading device under high temperature and a test loading method thereof, wherein the test loading device structure comprises a reaction frame, wherein the reaction frame is connected to a force transmission steel beam through two vertically arranged jacks, wherein one end of the force transmission steel beam is connected to one side of the reaction frame through a horizontally arranged jack, and the bottom of the force transmission steel beam is used to connect a test specimen. The test loading method designed based on the above test device of the present invention can realize independent changes in bending moment and axial force, and can be used in a mixed test of substructures under simulated fire by separate axial compression or eccentric compression loading.

Description

Technical Field

[0001] The invention relates to the technical field of test loading, and in particular to a column fire resistance test loading device under high temperature and a test loading method thereof. Background Art

[0002] Frame structure refers to a structure composed of beams and columns to bear the entire load of the building. It is widely used in the construction of civil buildings and industrial plants and is one of the most commonly used building structure types. Ensuring that the vertical load-bearing components are not damaged under fire is the primary factor in preventing the structure from continuous collapse. When designing frame structures, it is particularly important to study the failure mechanism of frame columns under fire. Frame columns are mainly damaged by the combined action of bending moment and axial force under vertical load. At present, traditional fire resistance test loading devices mainly realize the combined action of axial force and bending moment by applying axial load or eccentric load to the column. In actual structures, the axial force or bending moment at the column end often changes with the internal force of the adjacent structure, resulting in that in addition to the material and cross-sectional characteristics of the column itself, the main factor affecting the fire resistance of the column under fire is the constrained internal force (bending moment, shear force, axial force) between adjacent components. The traditional axial compression or eccentric compression loading method is simple, but it cannot achieve independent changes in bending moment and axial force. Therefore, separate axial compression or eccentric compression loading cannot be used in mixed substructure tests under simulated fire. Summary of the invention

[0003] The object of the present invention is to provide a column fire resistance test loading device under high temperature and a test loading method thereof, so as to solve the problems existing in the above-mentioned prior art, realize independent changes of bending moment and axial force, and be able to use separate axial compression or eccentric compression loading in substructure concrete tests under simulated fire.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a column fire resistance test loading device under high temperature, comprising a reaction frame, wherein the reaction frame is connected to a force transmission steel beam through two vertically arranged jacks, one end of the force transmission steel beam is connected to one side of the reaction frame through a horizontally arranged jack, and the bottom of the force transmission steel beam is used for connecting a test specimen.

[0006] Optionally, the reaction frame includes two symmetrically arranged reaction columns, and a horizontally arranged reaction beam is fixedly connected between the two reaction columns; the three jacks include a first jack, a second jack and a third jack, one end of the first jack and the second jack are slidably connected to the bottom of the reaction beam, and the other end is fixedly connected to the top of the force transmission steel beam, one end of the third jack is fixedly connected to one end of the force transmission steel beam, and the other end of the third jack is slidably connected to one of the reaction columns.

[0007] Optionally, one ends of the first jack, the second jack and the third jack are respectively fixedly connected to the force transmission steel beam through fixed hinge supports, and the other ends of the first jack, the second jack and the third jack are respectively fixedly connected to sliding supports, and four screws are fixedly provided on the sliding seats and connected to the slide plate; the sliding supports of the first jack and the second jack are fixedly clamped on the reaction beam through screws and nuts, and the sliding supports of the first jack and the second jack can drive the first jack and the second jack to achieve horizontal sliding, and the sliding support of the third jack is clamped on the reaction column through screws and nuts, and the sliding support of the third jack can drive the third jack to achieve vertical sliding.

[0008] The present invention also provides a column fire resistance test loading method under high temperature, comprising the following steps:

[0009] Step 1: Assemble the test loading device, hoist the test specimen, and after hoisting it to the position of the axial extension line of the first jack or the second jack, fix the test specimen to the force transmission steel beam and the ground;

[0010] Step 2: First, use the structural analysis software on the computer to establish a simulated fire-resistant structure model, set the fire-affected zones and the fire-affected zones of the beam and column structures, use the thermal-mechanical sequential coupling or thermal-mechanical coupling analysis method to perform mechanical analysis on the structural system when a fire occurs in different zones, extract the relationship curve between the column top internal force bending moment M0, shear force V0 and axial force N0 of the test specimen in the fire-affected zone and the fire-affected time, and save the curve data as a readable text file;

[0011] Step three, use the program on the control computer to read the data of bending moment M0, shear force V0, axial force N0 and fire exposure time, and determine the load values ​​of the first jack, the second jack and the third jack according to N2=M0 / L1, N1=N0-N2-N4 and N3=V0; wherein, N1 is the loading value of the jack coaxial with the test specimen, N2 is the loading value of the jack on the force-transmitting steel beam away from the test specimen, N3 is the loading value of the third jack, N4 is the sum of the deadweight of the force-transmitting steel beam and the weight of the third jack, and L1 is the horizontal distance between the loading points of the first jack and the second jack; and write the values ​​of N1, N2 and N3 into the control target input box of the corresponding jack control interface, and the loading control system controls the loading of each jack in real time according to the control target size until the test specimen reaches the destruction standard specified by the fire resistance limit, and the test is terminated.

[0012] Compared with the prior art, the present invention has achieved the following technical effects:

[0013] Conventional loading methods cannot freely control the magnitude of the bending moment and shear force acting on the test specimens during fire, but this loading scheme can freely adjust the loading values ​​of the bending moment or shear force acting on the test specimens according to the input data. Conventional loading methods cannot reflect the influence of the constrained internal forces of adjacent components on the fire resistance limit of vertical load-bearing columns during fire, but this loading scheme can set the independent variation relationship between the bending moment and the axial force according to the analysis results or design requirements, and test the minimum fire resistance limit of vertical load-bearing columns under various adverse working conditions.

[0014] In the past, when considering the fire resistance test of the overall effect of the structure, the overall structure or boundary constraints must be processed to test the fire resistance limit of the fire-affected columns. Limited by the size of the fire test furnace or boundary constraints, the fire resistance performance test can only be carried out by reducing the size and scale of the structure or component. This loading scheme uses computer numerical analysis technology to simulate the complex internal force effect of the non-fire-affected area of ​​the overall structure on the components in the fire-affected area, and examines the fire resistance limit of the load-bearing columns in the overall structure or under different fire conditions. It can be applied to fire resistance performance tests in a variety of situations, has a wide range of applications, and can greatly reduce the time and financial costs of the overall structure fire resistance performance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of the three-dimensional structure of the loading device for the column fire resistance test under high temperature of the present invention;

[0017] Figure 2 It is a schematic diagram of the planar structure of the loading device for the column fire resistance test under high temperature of the present invention;

[0018] Among them, 100 is a loading device for column fire resistance test under high temperature, 1 is a reaction frame, 101 is a reaction column, 102 is a reaction beam, 2 is a force transmission steel beam, 301 is the first jack, 302 is the second jack, 303 is the third jack, 4 is a sliding support, 5 is a fixed hinge support, 6 is a test specimen in the fire test furnace, 7 is a screw, 8 is a gasket, and 9 is a nut. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The object of the present invention is to provide a column test loading device and a test loading method thereof to solve the problems existing in the above-mentioned prior art, to achieve independent changes in bending moment and axial force, and to be able to use separate axial compression or eccentric compression loading in substructure concrete tests under simulated fire.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Reference Figure 1 and attached Figure 2 As shown, the present invention provides a column fire resistance test loading device 100 under high temperature, including a reaction frame 1 and three jacks. The reaction frame 1 is connected to a force transmission steel beam 2 through two vertically arranged jacks, one end of the force transmission steel beam 2 is connected to one side of the reaction frame 1 through a horizontally arranged jack, and the bottom of the force transmission steel beam 2 is used to connect to a test specimen 6 in a fire test furnace.

[0023] Specifically, the reaction frame 1 includes two symmetrically arranged reaction columns 101, and a horizontally arranged reaction beam 102 is fixedly connected between the two reaction columns 101; the three jacks include a first jack 301, a second jack 302 and a third jack 303, one end of the first jack 301 and the second jack 302 is movably connected to the bottom of the reaction beam 102, and the other end is fixedly connected to the top of the force transmission steel beam 2, one end of the third jack 303 is fixedly connected to one end of the force transmission steel beam 2, and the other end of the third jack 303 is movably connected to one of the reaction columns 101. One end of the first jack 301, the second jack 302 and the third jack 303 are fixedly connected to the force transmission steel beam 2 through a fixed hinge support 5, and the other ends of the first jack 301, the second jack 302 and the third jack 303 are fixedly connected to a sliding support 4, on which four screws 7 are fixedly provided, and gaskets 8 are passed through the ends of two adjacent screws 7, and nuts 9 threadedly connected to the screws 7 are provided at the ends of the gaskets 8 away from the sliding support 4; the sliding supports 4 of the first jack 301 and the second jack 302 are fixedly connected to the reaction beam 102 through the screws 7 and nuts 9 connected thereto, and the sliding support 4 of the third jack 303 is connected to the reaction column 101 through the screws 7 and nuts 9 connected thereto.

[0024] The present invention also provides a column fire resistance test loading method under high temperature, comprising the following steps:

[0025] Step 1, assembling the test loading device, first fix the two reaction columns 101 to the ground with bolts through the reaction columns 101 and the reserved holes on the ground, firmly connect the reaction beam 102 and the reaction column 101 together according to the height of the test specimen 6 in the fire test furnace, hoist the test specimen 6 in the fire test furnace, and after hoisting it to the position of the axial extension line of the first jack 301 or the second jack 302, fix the test specimen 6 in the fire test furnace with the force transmission steel beam 2 and the ground; the fixing method of the reaction column 101 and the test specimen 6 in the fire test furnace and the ground can be modified according to the actual situation of the laboratory, such as changing the connection between the bottom of the column and the ground from consolidation to hinged connection, etc.;

[0026] Step 2: Consider the control process of variable constraint effect test loading: First, use structural analysis software (such as Ansys, ABAQUS, MAC, Opensees and other mechanical analysis programs) on the computer to establish a simulated fire-resistant structure model, that is, a 3D or 2D model, and set the height or length of the fire-affected partition and the fire-affected area of ​​the beam and column structure, such as Figure 2 As shown in the figure, the dotted box area is the fire area, and the small dotted box areas at the upper and lower ends of the test specimen are fire protection areas. The thermal successive coupling or thermal coupling analysis method is used to perform mechanical analysis on the structural system when a fire occurs in different areas, and the relationship curves between the column top internal force bending moment M0, shear force V0 and axial force N0 of the test specimen in the fire area and the fire time are extracted, and the curve data is saved as a readable text file;

[0027] Step three, use a program on the control computer to read the data of bending moment M0, shear force V0, axial force N0 and fire exposure time, and determine the load values ​​of the first jack, the second jack and the third jack according to N2=M0 / L1, N1=N0-N2-N4 and N3=V0; wherein N1 is the loading value of the jack coaxial with the test specimen 6 in the fire test furnace, N2 is the loading value of the jack on the force transmission steel beam 2 away from the test specimen 6 in the fire test furnace, N3 is the loading value of the third jack 303, N4 is the sum of the dead weight of the force transmission steel beam 2 and the weight of the third jack 303, and L1 is the horizontal distance between the loading points of the first jack 301 and the second jack 302; and write the values ​​of N1, N2 and N3 into the control target input box of the corresponding jack control interface, and the loading control system controls the loading of each jack in real time according to the control target size until the test specimen reaches the destruction standard specified by the fire resistance limit, and the test is terminated.

[0028] In different embodiments, during the test, the influence of the internal force or displacement in the horizontal direction of the top of the test specimen on the fire resistance limit of the test specimen is not considered. The third jack 303 in this loading scheme can be cancelled, and the slide bases of the first jack 301 and the second jack 302 can be changed to a fixed base, and the bottom of the test specimen is changed from a fixed support to a hinged support, so that the fire resistance performance (fire resistance limit) of the test specimen under the combined action of different bending moment changes and axial forces can be examined.

[0029] In the description of the present invention, it should be noted that the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A column fire resistance test loading method at high temperature, characterized in that: A column fire resistance test loading device under high temperature is used, and the column fire resistance test loading device under high temperature includes a reaction frame, and the reaction frame is connected to a force transmission steel beam through two vertically arranged jacks, and one end of the force transmission steel beam is connected to one side of the reaction frame through a horizontally arranged jack, and the bottom of the force transmission steel beam is used to connect the test specimen; the column fire resistance test loading method under high temperature includes the following steps: Step 1: Assemble the test loading device, hoist the test specimen, and after hoisting it to the position of the axial extension line of the first jack or the second jack, fix the test specimen to the force transmission steel beam and the ground; Step 2: First, use mechanical analysis software on a computer to establish a numerical model of a simulated fire-resistant structure, set the fire-affected zones and the fire-affected zones of beam and column structures, and use thermal-mechanical sequential coupling or thermal-mechanical coupling analysis methods to perform mechanical analysis on the structural system when a fire occurs in different zones. Extract the relationship curves between the column top internal force bending moment (M0), shear force (V0) and axial force (N0) and the fire-affected time of the test specimens in the fire-affected zone in sections, and save the curve data as a readable text file; when the column top displacement of the numerical model exceeds 5% of the measured displacement, re-enter the numerical model according to the measured displacement of the column as a known condition, resubmit the calculation, and save the relationship curves between the column top internal force bending moment (M0), shear force (V0) and axial force (N0) and the fire-affected time as a readable text file; Step three, use the control program on the control computer to read the data of bending moment (M0), shear force (V0) and axial force (N0) and fire exposure time, and determine the load values ​​of the first jack, the second jack and the third jack according to N2=M0 / L1, N1=N0-N2-N4 and N3=V0; wherein, N1 is the loading value of the jack coaxial with the test specimen, N2 is the loading value of the jack on the force-transmitting steel beam away from the test specimen, N3 is the loading value of the third jack, N4 is the sum of the deadweight of the force-transmitting steel beam and the weight of the third jack, and L1 is the horizontal distance between the loading points of the first jack and the second jack; and write the values ​​of N1, N2 and N3 into the control target input box of the corresponding jack control interface, and the loading control system controls the loading of each jack in real time according to the control target size until the test specimen reaches the destruction standard specified by the fire resistance limit, and the test is terminated.

2. The column fire resistance test loading method under high temperature according to claim 1 is characterized in that: The reaction frame includes two symmetrically arranged reaction columns, and a horizontally arranged reaction beam is fixedly connected between the two reaction columns; the three jacks include a first jack, a second jack and a third jack, one end of the first jack and the second jack are movably connected to the bottom of the reaction beam, and the other end is fixedly connected to the top of the force transmission steel beam, one end of the third jack is fixedly connected to one end of the force transmission steel beam, and the other end of the third jack is movably connected to one of the reaction columns.

3. The column fire resistance test loading method under high temperature according to claim 2 is characterized in that: One ends of the first jack, the second jack and the third jack are fixedly connected to the force transmission steel beam through fixed hinge supports, and the other ends of the first jack, the second jack and the third jack are fixedly connected to sliding supports; the sliding supports of the first jack and the second jack are fixedly connected to the reaction beam through screws and nuts, and the sliding supports of the first jack and the second jack can drive the first jack and the second jack to achieve horizontal sliding, and the sliding support of the third jack is connected to the reaction column through screws and nuts, and the sliding support of the third jack can drive the third jack to achieve vertical sliding.

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