The Finite Element Analysis On Mechanical Properties Of The Concrete Filled Steel Tubular Compression Member With Separation

As a composite structure, concrete-filled steel tube structure has its unique properties.With the rapid development of social economy, concrete-filled steel tube structure iswidely applied in modern engineering construction, especially in the construction oflong-span arch bridge. However, concrete separation is a quality problem which is oftenencountered in the process of concrete pouring in the concrete-filled steel tube structure.This not only affects the interaction between steel tube and core concrete, resulting inmechanical properties reduction, but also leads to serious engineering accidents. Therefore,it is important to study adverse effect of separation concrete on mechanical properties ofconcrete filled steel tubular compression members.In this paper, according to actual state of separation concrete filled steel tubularcompression member, the analysis of adverse effect of separation concrete on mechanicalproperties of concrete filled steel tubular compression members is done by using of FEM.The analysis of separation axial compression members shows that its radial strain willincrease, hooping effect will decrease, ultimate bearing capacity will reduce, and itsmechanical performance will decrease with the separation ratio’s increase.The analysis of separation eccentric compression members shows that:(1) The steeltubes occur sag because or separation, the core concrete prematurely reaches the ultimatestrength because of separation ratio is too large, ultimate bearing capacity of membersreduce, even destroy is occurred, the effect is more significant than that of axialcompression members.(2) The larger the eccentricity ratio is, core concrete’s longitudinalstrain increases higher, its strength reduction is more serious, the bearing capacity ofmember decrease, mechanical performance of concrete filled steel tube members is weaken.(3) Bearing capacity of members significantly decrease when load is applied on the side ofseparation.(4) For long columns, bearing capacity’s influence is smaller than that of shortcolumns, but its failure characteristics is more obvious than that of short columns.