Research on hysteretic behavior of high-strength concrete-filled steel tubular members Wang Zhan Zhen Yonghui 21 Department of Construction Engineering, Shantou University, Shantou 515063; 2. Shenzhen Design Institute. The boundary surface model of the 58000 constitutive relationship in Guangdong Province, the finite element method was used to theoretically analyze the load-displacement hysteresis curve of the high-strength concrete-filled steel tube members, and the high-strength concrete-filled steel tube with a strength of 7 on 6 cores The experimental study of the hysteretic performance of the bending member compares the theoretical analysis with the results of this experimental study and other experimental studies, and analyzes the characteristics of the load-displacement hysteretic curve.
In recent years, high-strength concrete is being continuously promoted and applied in the engineering field, and it is increasing year by year. The shortcoming of high-strength concrete is its high brittleness, especially under the complex stress state, it will be controlled by brittle failure, and its reliability will be greatly reduced. Steel tube reinforced concrete components are ideal components with high strength and high ductility, and are the best way for high strength concrete to be used in engineering practice. The model for studying the load-displacement hysteresis curve of the high-strength concrete filled steel tube and its hysteresis curve is to use the interlayer shear model to charge the high-strength concrete structure of the steel tube. Date 20000509 Funded project 990792 The basis of elastoplastic seismic response analysis. Theoretical calculation of the load-displacement hysteresis curve is of great significance to the study of the working mechanism of high-strength concrete-filled steel tube members under repeated loads. In this paper, the finite element method is supplemented by the necessary tests to study the hysteretic performance of the high-strength concrete-filled steel tube structure. This not only has important practical value for the seismic design of the high-strength concrete-filled steel tube structure, but also studies the performance of high-strength concrete-filled steel tube members. It has definite theoretical significance 21.
Calculation of load-displacement hysteresis curve 2.1 Calculation assumption and loading method The high-strength concrete-filled steel tube members are spatial problems and should be solved using the spatial finite element method. In this paper, the parameters of space 20 nodes hexahedron are used. This kind of unit has high calculation accuracy and is widely used in space.
When the finite element method is used to analyze the high-strength concrete tube members, the assumption is made as follows: the constitutive relationship of the steel material adopts the double-line follow-up strengthening model 1; the constitutive relationship of the core concrete is calculated by the improved boundary surface model 231 The loading method can be divided into two types, one is force loading and the other is displacement loading. In this paper, the vertical load is applied by the force loading method, and the horizontal load is applied by the displacement loading method. The reason is that the force loading method will encounter great difficulties near the peak point, and it is impossible to calculate the falling section. In addition, due to the assumption of a flat section, in this question, only the total force of the external load is known and the section remains flat after the force is applied, and the distribution of the external load on the section is unknown. Therefore, the lateral load and the axial force cannot be converted into equivalent node loads acting on the nodes of the structure, so for this question, even in the elastic stage, the force loading method cannot be achieved.
The calculation method is relatively close and has a modern meaning. This article only discusses the flexural members, that is, a constant axial force is applied to the cantilever column, and then the lateral load is continuously increased to study the relationship between the lateral load and the lateral displacement.
There are two methods for calculating the load-displacement hysteresis curve, model column method and numerical analysis method. Calculating the load-displacement hysteresis curve with the model column method has the disadvantage of large errors, so this paper uses numerical analysis methods.
Experimental Research 3.1 Experimental Overview In order to better study the working performance of the steel pipe concrete upper bending and bending members and verify the correctness of the theoretical calculations, this paper conducted an experimental study on the high-strength concrete tubular bending members. The bottom plate made of 20-thick steel plates at the upper and lower ends of the test piece is welded to the column body with 25-height stiffeners to ensure the rigidity of the two ends of the column. The test uses a connecting rod mechanism. Load Sensor, Displacement Sensor Phase 4 Wang Zhan et al. Research on hysteretic performance of high-strength concrete flexural members of steel tubes The data transmission line is connected and then connected to the computer. Using the 1 River 1 data acquisition software developed by Tsinghua University, automatic data collection can be achieved. Continuous mining control is used. When the time interval is set to 5 data collection, the household can be drawn by monitoring the data curve. 5 Hysteresis curve.
It can be seen from the test results of test piece 3.2 that the two are basically in agreement. The existing errors are mainly caused by the following reasons. In the theoretical calculation, only the bending deformation of the component is considered, and the shear deformation of the component is not considered, which causes the theoretical curve. High stiffness.
The connection gap and friction force of each rod in the link mechanism makes the rigidity of the actual curve low.
In addition, some test results were collected in this paper, and compared with the results in this paper, the parameters of the test pieces in 5 and 6.5 are as follows, the steel pipe is 1335.1, the seamless steel pipe is 1335.1, the yield strength of steel is 347.71 concrete The cube strength is 70.2Nmm2; the axial force is 385kN and 865kN respectively. The parameters of the test piece in 6 are as follows: The steel pipe is ï¿ 1085 The axial force is 20kN and 270kN respectively.
The characteristics of the load-displacement hysteresis curve of Xing and Han legs From the previous theoretical analysis and experimental research results, it can be found that the load-displacement hysteresis curve of the concrete-filled steel tube has the following characteristics. The load-displacement hysteresis curves of members and ordinary strength concrete with steel tubes are very close.
No matter how the parameters of the components change, the shape of the load-displacement hysteresis curve is very full, and there is no pinch phenomenon. Conclusion Compared with the previous finite element analysis of concrete-filled steel tube members, the calculations in this paper are based on the material The selection of the model and the determination of the finite element model are different, and have new characteristics. On the basis of theoretical analysis and experimental research, this paper analyzes the characteristics of the load-displacement hysteresis curve of high-strength concrete-filled steel tubes.
Combining with the work done in this article, the author believes that it is possible to make progressive research on the following courses. Use the procedure of this article to study the basic performance of polygonal steel tube concrete members; use the calculation method of this paper to study the performance of eccentric compressive members of concrete filled steel tubes; The lateral resistance of short concrete columns is studied.
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