Study On Axial Compression Performance Of L-shaped Composite Concrete Filled Steel Tube Columns

Concrete filled steel tube composite column is a relatively new structure form,which can give full play to the advantages of both steel tube and concrete,and at the same time,composite column can be wrapped in the wall to increase the usable area of the house.In this paper,a new type of structure,L-shaped composite concrete filled steel tube column,is proposed.The axial compression performance of L-shaped composite concrete filled steel tube columns is analyzed by means of calculation theory,finite element analysis and experimental study.Both the unified theory and the quasi-steel theory treat steel tube and concrete as completely working together.The superposition theory has been verified by experiment s.In most cases,steel tube and concrete have gaps.The bearing capacity of the two materials is added together.In contrast,the superposition theory results are more conservative.Based on the superposition theory,this paper analyzes and studies the l-shaped battened concrete filled steel tube composite column,and proposes a formula for calculating the axial bearing capacity of L-shaped battened concrete filled steel tube composite column.ABAQUS finite element software was used to establish 7 groups o f finite element analysis models to study the influence of the bearing capacity and failure mode of the specimens under axial pressure respectively.By comparing the simulated load value with the calculated value,the correctness of the formula of axial co mpression bearing capacity derived on the basis of superposition theory is preliminarily verified.At the same time,the axial compression tests of five L-shaped composite columns of concrete filled steel tube were carried out to study the influence of the change of the area and slenderness ratio on the axial compression performance and failure morphology of the specimens,and to verify the accuracy of the simulation and modify the calculation formula.According to the simulation and test results,the stress on each part of the specimen is uniform in the elastic stage.Adding the battening plate effectively improves the integrity of the specimen.The improvement of bearing capacity is not obvious after the area of the hanging plate exceeds 60.The larger the slenderness ratio,the smaller the bearing capacity and the worse the ductility.The deviation between the test value and the simulation value is within 10%,and the simulation value is basically consistent with the calculated value.