Numerical Simulation And Tests On The Instability Of High Strength Steel Beam-columns

With the increasing widely application of high strength steel in the steel structures and bridges all over the world, it appears more important for study on its stability. Compared to the conventional steel structure, high strength steel has advantages in many advantages. The possibility of overall instability and local instability for high strength steel member is bigger, and the high strength steel structure is more easily crippling under the cyclic loading of severe earthquakes. However, at present, there are no studies on stability behavior of high strength steel structure under the cyclic loading of severe earthquakes, and the corresponding study basis for the seismic design methods of high strength steel structure is dificient. Therefore the study of on the instability of high strength steel structures under severe earthquakes has profound practical value.In order to overcome these above problems, the hysteretic behavior of high strength steel column under cyclic loading is studied. The main research includes:(1)The difference between codes in Chinese and American, Japanese and European seismic design cods for the limiting width-thickness ratio of steel column is studied, and analyzes the relationlity of Chinese seismic design code GB50011-2001.(2)The finite elment models are developed by using the general-purpose finite elment software, ANSYS, and the influence of initial geometric imperfection and residual stress are considered. The finite element models had been proved to be accurate based on the comparison between results from the finite element analysis and experiments. The hysteretic behavior of different strength steel column is analyzed by finite element model, and the influences of the yield ratio, ultimate strain and the yield plateau length are investigated.(3)Then this paper conducts an experiment of 6 Q460 steel I-columns and 5 Q460 steel Box-columns under cyclic loading, and the comparison study of damage phenomenon, hysteretic curve, energy dissipation and ductility is carried out. According to the test results, the influence of width-to-thickness ratio and axial-load ratio are studied. Suggestions for seismic width-to-thickness ratio of Q460 steel I-column and box-column have been presented, and the comparison between test results and calculate results of finite element analysis is carried out.(4)The numerical computer simulations of Q460 steel 1-column and box column under different constant compression is carried out with the validated finite elment model. According to the comparison of hysteretic curves, skeleton curves, coefficient of ductility, plastic adaption coefficient of cross-section and deformation capacity of columns, the influence of width-to-thickness ratio and axial-load ratio are studied, also the correlation between the width-to-thickness ratio of web and flange of I-column is studied.Then suggestions take into axial-load ratio for the width-to-thickness ratio limits of Q460 strength steelâ… -column and box columns are proposed.