初应力对钢管混凝土哑铃形长柱受力性能的影响

The influence of initial stress on the behavior of concrete filled steel tubular dumbbell shaped long columns

进行了初应力对钢管混凝土哑铃形轴压长柱试件的试验研究.在试验研究的基础上,进行了以长细比、偏心率和初应力度为参数的有限元分析,探讨了初应力对其力学性能的影响及其极限承载力的计算方法.分析结果表明,有初应力的钢管混凝土哑铃形柱的受力性能与有初应力的单圆管的相似.初应力使构件弹塑性阶段提前、弹性极限荷载及切线刚度降低.初应力对极限承载力影响不大,但随着长细比的增大而增加,长细比较小时对其可忽略不计.最后,给出了考虑初应力影响的钢管混凝土哑铃形构件极限承载力的实用计算方法.

An experiment for studying concrete filled steel tubular （CFST） dumbbell-shaped long columns by axial load with initial stress is carried out. Based on the testing, finite element analyses on CFST dumbbell- shaped columns are performed considering slenderness ratio, eccentric ratio and initial stress degree as param- eters. Influence of mechanical behaviors and calculation of ultimate load-carrying capacity on CFST dumbbell- shaped columns by initial stress are analyzed. The results indicate that the mechanical behavior of CFST dumbbell shaped columns is similar with that of CFST single tube ones, initial stress makes elastic-plastic phase appear ahead and decreases the tangent rigid and elastic ultimate load. However, the initial stress has almost no influence on the ultimate load-carrying capacity for the member of a little slenderness ratio. Initial stress will decrease stable ultimate capacity while the slenderness ratio is great. Finally, the method for calculateing the load carrying capacity of CFST dumbbell-shaped columns with initial stress is presented. The theoretical value agrees well with experimental results, it can be used in practical engineering.