Study On Hysteretic Behavior And Failure Mechanism Of Innovative Composite Steel Staggered Truss Structures

The composite steel staggered truss system has good economic performance dueto its large transverse rigidity and bearing capacity. Meanwhile, it has flexuralarchtectural planning. So it has attracted a widespread attention in the field ofstructural engineering. But, the transverse rigidity of this structral form is very weak,which tends to form a weak layer in lower part of structure. Based on the pre-existingresearch results, an innovative form is put forward in this paper to overcome thedefault, and study has been carried out on its seismic performance and failuremechanism. The main content in this article includes following parts:(1) Model test. A one-third scale specimen of five story innovative compositestaggered truss structure was designed according to similar theory and relevant codes.Based on a cyclic test, the hysteretic and the skeleton curves of the top storey drift v.s.base shear force were obtaied, and the bearing capacity, hysteretic characteristics,ductility and performance of plastic deformation, stiffness deterioration, the propertiesof seismic energy dissipation and failure mechanism of the structure were analyzed.Test results reveal that the structure’s hysteretic curves were stable and fullness, thusthe ductility and ability of deformation, energy dissipation and bearing capacity werewell. Since the lateral stiffness and bearing capacity is provided mainly by the truss,the fracture of the diagonal bars in the truss leads to structural failure. They shouldsatisfy the demand of brace in concentrate braced frame. The weak storey of thestructure was transferred from the bottom part to the upper, which meets the aim ofimprovement.(2) The analysis on behavior of the global structure. Firstly, the test was analyzed by finite element model by the FE software ANSYS. The numerical result is agreedwell with that of test in failure mechanism, bearing capacity, stiffness deterioration andoverall deformation, which proved the validity of the numerical model. After that,parametic studies on the innovative composite staggered trusses system wereproceeded systematically, including5series: truss span; truss height; middle panelwidth of truss, number of the truss panel, and so on.(3) Based on the results of experiment and numerical analysis, suggestions forseismic design are presented in width-to-thickness ratio of diagonal truss, reasonablevalues of truss span and truss height, which may be reffered by practice design.