残余应力和应变率对地震作用下钢柱的循环屈曲影响
|
摘要
对4个足尺W型柱试件进行受压屈曲试验,研究强震下多层支撑钢框架中柱的屈曲性能。工况包括单调、循环的轴心和偏心加载。在其中一个试验中施加动力循环荷载,在另一个循环试验中施加端弯矩。柱截面尺寸为W310×129(类型1),材质为ASTMA992钢。研究柱的长细比为48时绕弱轴屈曲的性能。基于杆件横截面的纤维离散化,采用数值方法模拟试件的响应。在数值模型中,描述并考虑了柱残余应力和应变率对材料属性的影响。研究表明:在地震作用下,钢柱能持续几个非线性屈曲循环,并承受重力荷载。仅在首次屈曲时,残余应力对柱的性能有影响,并在屈曲和降低受压承载力之前逐渐降低柱的切向刚度。强震下的高应变率提高了柱的屈曲强度和后屈曲强度。当采用非线性梁柱单元时,能充分预测钢柱的循环屈曲性能。在本模型中,通过横截面纤维离散化考虑了残余应力和应变率的影响。
Compression buckling tests were performed on four full-scale W-shaped column specimens to investigate the buckling response of columns in multi-storey braced steel frame structures subjected to seismic strong ground motions.The test protocols included monotonically and cyclically applied concentric and eccentric axial loading.One test was conducted under dynamic cyclic loading.End moments were applied on one cyclic test.The columns were W310×129compact(class 1)sections made with ASTM A992steel.Weak axis buckling was studied and the column had an effective slenderness ratio of 48.The response of the test columns was also examined using numerical simulations based on fibre discretization of the member cross-section.Column residual stresses and strain rate effects on the material properties were both characterized and accounted for in the numerical models.The study showed that steel columns can sustain several cycles of inelastic buckling under seismic induced loading while maintaining sufficient compressive resistance to support the applied gravity loads.Residual stresses affected the column response only at the first buckling occurrence with a gradual reduction of the columns'tangent stiffness prior to buckling as well as a reduction of the column's compressive resistance.High strain rates anticipated during strong earthquakes increased the column buckling and post-buckling strengths.The cyclic buckling response of steel columns can be predicted adequately when using nonlinear beam-column elements and cross-section fibre discretization provided that residual stresses and strain rate effects are included in the modelling.
Compression buckling tests were performed on four full-scale W-shaped column specimens to investigate the buckling response of columns in multi-storey braced steel frame structures subjected to seismic strong ground motions.The test protocols included monotonically and cyclically applied concentric and eccentric axial loading.One test was conducted under dynamic cyclic loading.End moments were applied on one cyclic test.The columns were W310×129compact(class 1)sections made with ASTM A992steel.Weak axis buckling was studied and the column had an effective slenderness ratio of 48.The response of the test columns was also examined using numerical simulations based on fibre discretization of the member cross-section.Column residual stresses and strain rate effects on the material properties were both characterized and accounted for in the numerical models.The study showed that steel columns can sustain several cycles of inelastic buckling under seismic induced loading while maintaining sufficient compressive resistance to support the applied gravity loads.Residual stresses affected the column response only at the first buckling occurrence with a gradual reduction of the columns'tangent stiffness prior to buckling as well as a reduction of the column's compressive resistance.High strain rates anticipated during strong earthquakes increased the column buckling and post-buckling strengths.The cyclic buckling response of steel columns can be predicted adequately when using nonlinear beam-column elements and cross-section fibre discretization provided that residual stresses and strain rate effects are included in the modelling.
引文
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心