钢筋混凝土柱低周疲劳全过程累积损伤性能简化分析方法

Simplified method for analysis of damage characteristic of RC columns under and after low cyclic loading

为了有效预测地震作用下钢筋混凝土柱的低周疲劳损伤累积程度与损伤后的剩余承载能力,提出了一种基于单调荷载-位移关系并考虑低周疲劳效应的钢筋混凝土柱损伤承载能力简化分析方法。首先,根据自洽方法并假设裂纹符合Weibull分布,提出了基于细观机理的混凝土损伤模型,给出了混凝土损伤指标与有效模量、应变的定量表达式,并通过非线性数值分析得到了钢筋混凝土柱的单调荷载-变形曲线;然后,通过分析纵筋的塑性低周疲劳损伤,建立了基于割线刚度的钢筋混凝土柱低周疲劳变形性能损伤计算模型,模型参数根据试验研究获得,推导了柱割线刚度和抗力的衰减规律计算公式;最后,在以上工作的基础上,分析低周疲劳作用对钢筋混凝土柱底截面混凝土和纵筋应变的累积增大效应,得到混凝土损伤后的有效弹性模量,提出了考虑低周疲劳损伤后的钢筋混凝土柱承载能力和变形能力计算方法。编制非线性损伤分析程序,对损伤后试验柱进行了计算分析。结果表明,该方法得到的计算值与试验值的相对误差处于合理范围之内,验证了该方法的可靠性和实用性。

In order to predict cumulative damage and residual capacity of reinforced concrete columns （RC） under and after cyclic loading, a simplified numerical method based on lateral load-deformation relations of RC columns under monotonic and cyclic loading is suggested. In the simplified method, a multi-scale concrete damage model, which is a quantitative expression of damage factor of concrete effective module and concrete strain, is proposed by using the consistent method and the Weibull statistical analysis. The lateral load-deformation relation of RC columns under monotonic loading is obtained through a non-linear numerical analysis. Secondly, according to the analysis of longitudinal bar plastic accumulated damage, a new damage model for compression-bending columns is proposed. The parameters are determined by means of experimental results obtained from the existing work. The degradation law of secant stiffness and resistance capacity is presented. At last, based on the above-mentioned work, the cumulated strain of concrete and longitudinal reinforcement in the columns are obtained, as well as the concrete effective elastic module. Then the numerical method for estimating residual beating capacity and deformation of RC columns after cyclic loading is presented. A nonlinear damage analysis program is developed to validate the calculating results of the columns after cyclic loading tests. The results show that the relative errors of both the simulation and tests are controlled within the scope of engineering errors, which verifies the reliability and applicability of the numerical analytical method.