| In recent years,as the change of architectural style,structure form and space service function,the conventional concrete filled steel tube composite frame can’t meet the requirements.The Ab normal joint forms become a trend.The unequal depth beams become one of the key research.Although our country has given the related construction suggestion to panel of unequal depth beams joints,but the theory support to the design method of the panel is not perfect,and the lack of relevant experience.A large number of scholars have carried out research and Discussion on concrete filled steel tube joints with exterior diaphragms,but there have been few scientific studies on unequal depth beams to conc rete filled steel tube joints with exterior diaphragms.The joints with exterior diaphragms can ensure the continuity of the column,reduce the effect of welding residual stress on the component,so exterior diaphragms have obvious advantages in unequal depth beams joints.In this paper,Research and analysis on unequal depth beams to concrete filled steel tube joints with exterior diaphragms,the force mechanism and mechanical properties of panel zone were investigated and some reference for applications and popularize in engineering practice were Provided.Finite element analysis was carried out on the four test components of different beam depth ratio and loading ways by using finite element analysis software MSC.Marc to validate the reliability of the finite element model.Analysis parameters including size effect,width to thickness ratio of columns,depth to width ratio of panels,axial compression ratio,width ratio of beams and columns,width to thickness ratio of beam flanges and depth to width ratio of beam webs,the influence on the shear bearing capacity,stress distribution and failure models of panels were investigated.The analytical results indicated that:(1)With the increase of width to thickness ratio of columns and depth to width ratio of panels and width to thickness ratio of beam flanges,the shear capacity of pannels were reduced.With the increase of beam depth ratio,width ratio of beams and columns,the shear capacity of pannels were improved.With the increase of axial compression ratio,the shear bearing capacity of pannels were increased slightly in a certain range,but after the axial compression ratio reaches 0.4,the late bearing capacity of pannels decreased slightly;Component s size and depth to width ratio of beam webs had no significant effect on shear bearing capacity of pannels;In addition,With the decrease of beam depth ratio and width to thickness ratio of columns,the initial shear stiffness of panel were reduced,the other parameters had little impact on it.(2)The failure modes of panels depending on the loading direction were divided into four.Under positive load,diagonal inclined cracks of concrete form through panel 1 and panel 2.The failure of steel tube was divided into two forms,including loca l shear failure of panel 1 and general shear failure of the whole panel,these were failure modes 1 and failure modes 2 of panne l,respective ly.Under negative load,diagonal inclined cracks of concrete form through the panel 1.The failure of steel tube was still divided into two forms,inc luding loca l shear failure and general shear failure,these were failure mode 3 and failure mode 4 of pannel,respectively. |
