Study On Hysteretic Behavior Of The Welded Cruciform Bulit-up Columns With H-section Steel Under Axial Compression

H-section steel as an open section is easy to connect with various forms of structural components,reasonable application of large width to thickness ratio of H-section steel components’ ductility and energy dissipation capacity can not only ensure the safety of the structure but also achieve the purpose of saving steel,so cruciform columns welded with three H-section steel are proposed.In this paper,48 Q355 models and 48 Q460 models with different flange width-thickness ratios and different web depth-thickness ratios under different axial compression ratios are designed.Considering the initial geometric imperfection of the components and the non-linearity of the material,the finite element simulation under constant axial compression and horizontal cyclic loading are systematically carried out.The models are used to investigate the influence of steel strength,axial compression ratio and width-tothickness ratio on the hysteretic behavior of the components,and the holistic seismic behavior of these models are evaluated.The research work and conclusions of this paper are as follows:(1)The finite element simulation analysis of the cross-shaped column with flange under constant axial compression and horizontal cyclic loading is carried out.The accuracy and reliability of the finite element analysis method are verified by comparing the experimental results with the finite element simulation results.(2)Basing on finite element analysis of 96 models of the welded cruciform built-up columns with H-section steel under constant axial compression and horizontal cyclic loading,this paper analysed the process of their deformation and failure,studied their hysteretic behavior such as hysteretic curve,beating capacity,skeleton curve,energy-dissipation capacities and so on,also discussed the influencing rule of flange width-thickness ratio,web depth-thickness ratio and axial compression ratio on the hysteretic behavior.The results show that the failure modes of the models are basically the same,and they all belong to local buckling instability failure with plenty plastic deformation.Compared with high-strength steel Q460 components,ordinary steel Q355 components have better hysteretic behavior.The influence of flange widththickness ratio,web height-thickness ratio and axial compression ratio on the hysteretic behavior of Q355 components and Q460 components are basically the same,that is the hysteretic behavior decreases with the increase of the above parameters.(3)When considering the width-thickness ratio of the welded cruciform built-up columns with H-section steel according to the width to thickness ratio limit of I-section grade proposed in China seismic code(GB 50011-20l0),the evaluation is based on the finite element analysis results.We can find that the influence of axial compression ratio is not taken into account on the limit of the width-thickness ratio of the I-section,the correlation between the flange and web of width-thickness ratio is also not considered.Finally,according to the requirements of seismatic beating capacity and holistic seismic performance,the limit values of flange widththickness ratio and web depth-thickness ratio under different axial compression ratio for application of the welded cruciform built-up columns with H-section steel are proposed,which provides a theoretical basis for engineering application and the preparation of technical regulations for steel special-shaped column structures.