Nonlinear Finite Element Analysis And Experimental Researchof Special-shaped Columns Steel Frame Aseismic Performance

With the development of construction industry in China, exploitations of landresources are increasingly serious, leading to the shortage of housing area in cities.Inorder to solve this problem and improve utilization rate, developing a new type ofeffective structure system becomes an inevitable trend therefore.In recentyears,special-shaped column structure is widely applied in the residential structuresystem. Together with the advantages of steel structure in seismic behavior, a kind ofsteel frame system is devised, in which the special-shaped (L-shaped, T-shaped,cross-shaped etc.) columns replace the normal (box-shaped, H-shaped) ones. It cannot only solve the problems of protruding angles of columns, which bring trouble forindoor arrangement, but also meet the demands of promoting housing industrializationand the strategy of sustainable development with great practical significance.By the support of Natural Science Foundation of ChinaTheoretical andExperimental Research of Steel Structure System with Specially Shaped Columns(project numbers:50878008), this paper summarizes the characteristics of steel framewith special-shaped columns, and puts forward some actual problems to be solved forseismic behavior. Then a high-rise steel frame with special-shaped columns inearthquake zone is taken as research object. According to the particularity of theL-shaped column, this paper has analyzed its seismic performance using the combinedmethods of Finite Element and experiment.A nonlinear Finite Element model is established herein for the research onseismic behavior of steel frame with special-shaped column under low cyclic reversedloading. Ten models with different sections are designed, and the total process ofload-carrying, deformation and destruction have been simulated, through thecalculation of nonlinear finite elements under the dead and low cyclic axial force.Theindexes of seismic performance are investigated, such as hysteresis curve, skeletoncurve and energy dissipation capacity. Furthermore, the influences of axialcompression ratio, height-thickness ratio of web, width-thickness ratio of flange areobtained as main factors for earthquake resistant capacity.Then, elastoplastic time-history analysis is applied for the steel frame withspecial-shaped columns and normal columns, under rare earthquakes on the zone offortification intensity8. By comparing parameters of these two structures, such asbase shear, vertex acceleration, maximum floor displacement and inter-story shiftratio, combined with the standard aseismatic performance evaluation.In order to study more comprehensively, three one-second-scale models of steelplane frame with L-shaped columns are designed for pseudo-static experiments under low cyclic reversed loading.The deformation modes, strain distribution, plastic hingedistribution and failure modes are researched in detail, as well as the indexes ofseismic behavior e.g. hysteresis curve, skeleton curve, load-carrying capacity,ductility performance, energy dissipation capacity, strength degradation and stiffnessdegradation.Combined with the finite element analysis, obtain the influence law of theseismic performance by the high thickness ratio of column webs.