圆截面RC桥墩曲率极限状态和延性的概率分析

Probability analysis of the curvature limit state and ductility of circular RC bridge piers

从变形能力的不确定方面研究了圆截面钢筋混凝土桥墩曲率极限状态和曲率延性系数。把截面的材料参数和几何尺寸看作随机变量,采用拉丁超立方体抽样模拟法分析了在不同的轴压比、纵筋配筋率和配箍率下桥墩截面无量纲屈服、服务和破坏控制曲率极限状态的概率特性。结果表明,截面的无量纲曲率极限状态近似服从正态分布,轴压比是影响无量纲屈服和服务水平曲率极限状态均值的主要因素;轴压比和配箍率是影响无量纲破坏控制水平曲率极限状态均值的主要因素;无量纲曲率极限状态的变异系数随着截面变形的增加而增加。另外,还分析了桥墩截面在服务和破坏控制极限状态下曲率延性系数的概率分布特征值,通过回归分析提出了用桥墩截面设计参数计算曲率延性系数特征值的近似计算公式。

The curvature limit state and curvature ductility factor of circular reinforced concrete bridge piers are investigated in terms of the uncertainty in deformation capacity. Material and geometric parameters are modeled as random variables, and using the LHS simulation, the probabilistic parameters of the limit states of dimensionless yielding, serviceability and damage control curvature are calculated for different axial load ratios, longitudinal reinforcement ratios and transverse reinforcement ratios. The results indicate that the dimensionless curvature limit state generally follows a normal distribution, that the axial load ratio is the main factor affecting the mean value of the dimensionless yielding and serviceability curvature limit states, and that the axial load ratio and transverse reinforcement ratio are the crucial factors associated with the dimensionless damage control curvature limit state. Furthermore, the characteristic values of the curvature ductility factors for the serviceability and the damage control limit states are obtained, and two equations for estimating the characteristic values of the curvature ductility factors are developed through regression analysis.