Study on mechanical performace of new circular concrete-filled steel tube column-concrete beam connection joints with openings
The circular concrete-filled steel tube column-concrete beam connection joint of traditional steel-concrete hybrid structure has the situation that the steel bar crisscrossed needs to avoid or open the hole with the steel member,the joint structure is complex,the construction is difficult,and this joint becomes the design and construction difficulty of steel-concrete hybrid structure.So,the new circular concrete-filled steel tube column-concrete beam connection joint was proposed,and combining with the project experience of adopting steel-concrete hybrid structure in recent years,the finite element analysis of this kind of joint was carried out.The influence of axial pressure at the top of the column and horizontal force at the end of the column on the mechanical properties of each part of the joint was studied.The results show that the change of axial pressure at the top of the circular concrete-filled steel tube column significantly affects the stress of each member at the steel pipe openings,and the off-center force reduce the bearing capacity of the circular concrete-filled steel tube column.At last,considering a certain degree of weakening of circular concrete-filled steel tube columns by steel tube wall openings,four types of strengthening measures were adopted,and the load-stress curves of steel tubes under those measures were analyzed.The result show that thickening the wall of steel tube at the location of the openings is the most effective way.Setting up the inner ring plate is also effective in reducing the stress concentration effect.The load-stress curves of the circular concrete-filled steel tube column with vertical disconnected stiffeners are basically the same as those with vertical continuous stiffeners,the installation of vertical disconnected stiffeners have more significant advantages because of the less steel requirement.
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