Exposed To Fire Steel Staggered Truss Structural Lateral Force Resisting Response Analysis And Experimental Research

Steel staggered-truss framing system is a new system which is highly efficient for resistance to the lateral loading. It has been applied in more and more projects for the past few years, but it is only studied in theory in China. The lateral performance of steel staggered-truss framing system under fire exposure is studied in this thesis, supported by National Natural Science Foundation of China (Grant No.50706059), the open fund of State Key Laboratory of Fire Science of University of Science and Technology of China (Grant No. HZ2009-KF05) and the graduate education innovation project of Central South University. The mechanical response of steel staggered-truss framing system under fire exposure and the influence factor of the lateral performance are investigated by the method of theoretical analysis, finite element analysis and experimental study.The main content and conclusions of the study are as follows(1) A simplified model is presented for describing the lateral displacement of steel staggered-truss framing system subjected to high temperature according to the structural attributes. And the numerical method of lateral displacement of the system under fire exposure is proposed.(2) In order to study the structural behaviors of the Steel staggered-truss framing system at elevated temperature under the lateral force, a numerical investigation, based on a three-dimensional structural model, was presented by the finite element method, using the software of ANSYS. The axial forces, bending moments and displacements versus temperature are analyzed and the interaction characteristics between the truss exposed to fire and its adjacent truss are studied. Simultaneously, the change law of the lateral displacement versus temperature is discussed and the lateral performance of the structure under high temperature is studied too.(3) The influence factors of the lateral performance of the steel staggered-truss framing system are discussed under different parameter using finite element models. The height of structure, ratio of height and span of truss and the weight of vierendeel panel are considered respectively. The results indicate that:the increasing of the height of structure makes little influence on the lateral performance of the system under fire exposure when the load is allowable. The lateral displacement caused by high temperature at the storey exposed to fire may increase for the augmentation of the ratio of height and span to the truss. And the lesser weight of vierendeel panel will be more conducive to the lateral performance of steel staggered-truss framing system under fire exposure.(4) An experimental investigation on the structural behaviors of a six-storey steel staggered-truss framing system model with a scale of 1/8 under lateral force and fire exposure is carried out to proof the correctness of the simplified model and the finite element model. It is found that the results of simplified model and finite element model have a good agreement with the experimental data.It is hoped that some information can be presented for the further research and fire-resistant design of staggered truss system by the study and fire test in this thesis.