Study On Behavior Of Square CFDST Under Transverse Local Compression

Concrete-filled double-skin steel tube (CFDST) is a new type of composite member developed from traditional concrete-filled steel tube (CFST). CFDST not only inherits the advantages of CFST, including good plasticity and toughness, good fire and corrosion resistance ability, high bearing capacity, ease for construction, and etc, but also has larger cross-section and bending stiffness, lighter weight and better fire performance compared with traditional CFST. CFDSTs have the potential to be used as bridge piers, legs of offshore platform in deep water, large dimensional columns in buildings and other towering structures, and at the same time the hollow characteristics make it possible to be employed in truss and space structures. CFDST may be subjected to transverse local compression when used as chords in truss and space structures. The behavior of CFDST under transverse local compression will directly affect the performance of CFDST truss and space structures, and even determine the safety of entire structure.This paper experimentally and theoretically investigates the behavior of CFDST under transverse local compression. The main contents are as follows:(1) Review of studies on behavior of CFDST members and performance of traditional CFST under transverse local compression was carried out.(2) To investigate the influence of main parameters on the performance of square CFDST under transverse local compression, sixteen specimens with the variation of width ratio between bearing member (BM) and specimen, hollow ratio, wall thickness of outer tube and type of BM were tested.(3) Based on the determination of constitutive model of steel and concrete, a finite element analysis (FEA) model for simulating the behavior of square CFDST under transverse local compression was developed using the software ABAQUS, and the predicted failure pattern, load versus deformation curve and bearing capacity generally agreed well with the experimental results.(4) Based on the systematically parametric analysis, the simplified formula for bearing capacity of square CFDST under transverse local compression is proposed, and the simplified results are generally in good agreement with the numerical and experimental results.