（重庆三峡学院土木工程学院， 重庆 404000）

［摘要］为了研究疲劳荷载作用下钢筋混凝土梁承载力退化规律，在研究其疲劳刚度退化基础上建立了承载力退化模型。首先基于截面有效惯性矩理论并考虑刚度折减得到了静载作用下钢筋混凝土梁的刚度计算表达式； 然后，将得到的静载短期刚度作为疲劳荷载作用下梁的初始刚度，通过选择退化函数、采用数据拟合确定函数参数后建立了疲劳荷载作用下的刚度退化计算公式； 最后，以疲劳损伤作为纽带，通过挖掘刚度损伤和承载力损伤之间的内在关系，建立了疲劳荷载作用下钢筋混凝土梁基于刚度退化的承载力退化模型。研究结果表明:承载力在疲劳初期、构件接近破坏阶段下降较快，而中间较长时间基本呈线性退化，并与刚度的衰减较为一致，退化曲线都呈现S形形态； 通过建立的承载力退化模型，可以用最少量剩余承载力的破坏性试验，实现疲劳后钢筋混凝土梁承载力的准确、快速、有效预测。

［关键词］桥梁工程； 钢筋混凝土梁； 疲劳刚度； 刚度退化函数； 承载力退化模型

中图分类号：TU375, U441-4文献标识码：A文章编号：1002-848X(2020)22-0099-06

Research on bearing capacity degradation model of reinforced concrete beams based on fatigue stiffness degradation

LIU Fangping, YI Wentao

(School of Civil Engineering, Chongqing Three Gorges University, Chongqing 404000, China)

Abstract:In order to study the degradation law of bearing capacity of reinforced concrete beams under fatigue load, bearing capacity degradation model was established based on the study of fatigue stiffness degradation. Firstly, based on the effective moment of inertia theory of cross-section and considering stiffness reduction, the stiffness calculation expression of reinforced concrete beams under static load was obtained. Then, the short-term stiffness under static load was taken as the initial stiffness of beams under fatigue load, and the stiffness degradation calculation formula under fatigue load was established by choosing the degradation function，in the process, data fitting method was used to determine function parameters. Finally, fatigue damage was taken as the link, a bearing capacity degradation model of reinforced concrete beams under fatigue load based on stiffness degradation was established by excavating the internal relationship between stiffness damage and bearing capacity damage. The results show that the bearing capacity decreases rapidly in the initial fatigue stage and near failure stage, and the linear degradation occurs in the middle for a long time, which is consistent with the attenuation of stiffness, and both of them present the S-type degradation curves. Through the bearing capacity degradation model established, the bearing capacity of reinforced concrete beams can be accurately, rapidly and effectively predicted by the minimum destructive bearing capacity experiment of residual bearing capacity.

Keywords:bridge engineering； reinforced concrete beam； fatigue stiffness； stiffness degeneration function； bearing capacity degradation model

*重庆市自然科学基金项目（cstc2018jcyj，AX0360），重庆市教委科学技术研究项（KJQN201901207，KJQN202001204），重庆市三峡水库岸坡与工程结构灾变防控工程技术开放基金项目（SXAPGC18ZDI01）。

作者简介：刘芳平，博士，副教授，硕士生导师，Email：115090140@qq.com。