圆钢管柱变形性能研究

Deformation Performance of Steel Pipe Columns

针对支承大跨度屋盖钢管柱的受力特点,进行了3个低轴压比钢管柱在水平往复荷载下的模型试验.采用非线性有限元法对钢管柱的变形性能进行计算分析,分别考察长细比、径厚比和轴压比对钢管柱屈服变形角和极限变形角的影响.试验结果表明:当轴压比为0.2左右时,钢管柱在水平往复荷载作用下,钢管柱的滞回曲线均为饱满的梭形.当径厚比较小时,钢管柱塑性变形发展减缓,损伤程度下降,耗能能力增强;当长细比较小时,钢管柱塑性变形发展加快,耗能能力减弱.钢管柱进入弹塑性阶段后,底部发生环向外凸变形,在达到极限承载力时,柱底外鼓非常显著.屈服变形角和极限变形角均远大于规范限值.有限元分析结果表明:钢管柱的屈服变形角与轴压比、长细比均呈线性关系;长细比对钢管柱屈服变形角的影响最大,轴压比次之,径厚比的影响最小;当长细比不小于40时,钢管柱屈服变形角可以达到1/150的性能目标.钢管柱的极限变形角与轴压比和长细比均呈线性关系,与径厚比呈非线性关系;径厚比对钢管柱极限变形能力的影响最大,轴压比次之,长细比影响最小;当轴压比不超过0.2、径厚比不大于30时,钢管柱极限变形角可以达到1/30的性能目标.通过对有限元分析结果进行数值拟合,分别得到钢管柱屈服变形角和极限变形角的计算公式,可用于钢管柱变形能力的估算.

Based on the mechanical features,three tests with different specimens were performed on steel pipe columns with low axial compression ratio,supporting large-span roofs under reversed horizontal loading.The nonlinear finite element method was used to analyze the deformation performance of steel pipe columns,and the effects of slenderness ratio,diameter-thickness ratio,and axial compression ratio on the yield deformation angle and ultimate deformation angle were investigated.The test results show that when the axial compression ratio is about 0.2,the hysteresis curves generated by the steel pipe columns under reversed horizontal loading show a full shuttle shape.When the diameter-thickness ratio is relatively small,the rate of plastic deformation of the steel pipe column is slowed down,the degree of damage is reduced,and the energy dissipation capacity is enhanced.When the slenderness is relatively small,the growth of plastic deformation of the steel pipe column is accelerated and the energy dissipation capacity gets weakened.As the steel pipe column enters the elastoplastic zone(behavior),a ring form of deformation occurs peripherally or externally at the bottom and a drum form of deformation occurs directly at bottom of the column.These deformations significantly affect the ultimate bearing capacity.The yield deformation angle and the ultimate deformation angles are much larger than those mentioned in the specification.The finite element analysis results show that the yield deformation angle has a linear relationship with the axial compression ratio and the slenderness ratio;the slenderness ratio has the maximum influence on the yield deformation angle,the axial compression ratio has some influence when compared to slenderness ratio(second in the order of influence),and the diameterthickness ratio has minimum influence.When the slenderness ratio is not less than 40,the yield deformation angle can satisfy the required target drift angle of 1/150.The ultimate deformation angle of steel pipe columns has a linear relationship with the axial compression ratio and the slenderness ratio and has a nonlinear relationship with the diameter-thickness ratio;the diameter-thickness ratio has the largest influence on the ultimate deformation capacity of steel pipe columns,the axial compression ratio is the second(has some influence),and the slenderness ratio has the least influence.When the values of axial compression ratio and the diameter-thickness ratio do not exceed 0.2 and 30,respectively,the ultimate deformation angle of steel pipe columns can satisfy the required target drift angle of 1/30.By applying the results of finite element analysis in the calculations,yield deformation angle and ultimate deformation angle of steel pipe columns are obtained,which are used to estimate the deformation capacity of steel pipe columns.