高强圆钢管混凝土压弯构件(1):数值分析

由于具有比普通构件强度高、刚度大等特点,高强圆钢管混凝土压弯构件被广泛用于高层建筑中。然而,针对此类构件的大多数非线性分析方法都没有考虑高强材料属性和混凝土约束的影响,这很大程度上高估了核心混凝土的强度和韧性。因此,这些方法的求解结果与试验结果相差很大。针对高强圆钢管混凝土压弯构件的非线性性能,提出新的数值模型。该模型不仅考虑了混凝土约束对核心混凝土和钢管的影响,还考虑了压弯构件的初始几何缺陷。根据通过有限元分析求得的轴力-弯矩曲线,确定压弯构件非线性稳定分析中的平衡状态。为确定轴力-变形及轴力-弯矩曲线,提出了计算准则。在计算机程序中应用该数值模型,可研究高强圆钢管混凝土压弯构件的基本性能。在后续文章中,将验证该模型的正确性,并应用此模型。

High Strength Circular Concrete-Filled Steel Tubular Slender Beam-Columns,Part I:Numerical Analysis

High strength circular concrete-filled steel tubular(CFST)slender beam-columns are frequently used in highrise composite buildings because they possess higher strength and stiffness than normal strength ones.Most nonlinear inelastic methods of analysis for circular CFST slender beam-columns have not considered the effects of high strength materials and concrete confinement that significantly increases the strength and ductility of the concrete core.As a result,these methods produce computational solutions that deviate considerably from experimental results.This paper presents a new numerical model for predicting the nonlinear inelastic behavior of high strength circular CFST slender beam-columns under axial load and bending.The numerical model developed not only accounts for confinement effects on the concrete core and circular steel tubes but also incorporates initial geometric imperfections of beam-columns.Axial load-moment-curvature relationships obtained from the fiber element analysis of column cross-sections are utilized to determine the equilibrium states in the inelastic stability analysis of slender beam-columns.Computational algorithms are developed for determining the axial load-deflection and axial load-moment interaction curves for slender beam-columns.The numerical model is implemented in a computer program,which is shown to be an efficient and accurate simulation tool that can be used to investigate the fundamental behavior of high strength circular CFST slender beam-columns.The verification and applications of the numerical model are given in a companion paper.