(1重庆科技学院建筑工程学院， 重庆 401331； 2 能源工程力学与防灾减灾重庆市重点实验室， 重庆 401331)

［摘要］RC框架梁受弯损伤会发生轴向伸长，周边构件对梁伸长的约束作用会在梁中产生不可低估的轴力，显著提高其抗弯承载力，此现象未得到足够重视。RC框架梁抗弯承载力非预期超强可能导致结构在强震中难以出现预期的强柱弱梁破坏模式，造成结构倒塌。为研究地震作用下RC框架梁受弯损伤轴向伸长效应，首先阐明了梁伸长的概念，并从机理上揭示了梁伸长的必然性及其构成，基于试验研究定性分析了梁伸长规律；发现了目前尚缺乏全面综合考虑梁伸长效应的分析模型；归纳分析了梁伸长效应对结构抗震性能影响规律的研究进展及忽略此效应可能引发的问题。最后指出亟待开展考虑梁受弯损伤轴向伸长效应的RC框架结构强震破坏模式及抗震性能的系列基础性研究，为进一步完善框架结构抗震延性设计方法提供支撑。

［关键词］梁伸长； 破坏模式； 抗震性能； 数值模拟； 钢筋混凝土框架结构

中图分类号：TU375-1文献标识码：A文章编号：1002-848X(2019)13-0098-08

Study on axial elongation effect of RC frame beams due to bending damage under earthquake

Wang Liping1,2， Zhang Wei1， Luo Wenwen1,2

(1 Architectural and Civil Engineering Institute, Chongqing University of Science and Technology, Chongqing 401331, China；  2 Chongqing Key Laboratory of Energy Engineering Mechanics & Disaster Prevention and Mitigation,  Chongqing 401331, China)

Abstract:The bending damage of RC frame beams leads to axial elongation. The restraint effect of surrounding members on the elongation of beams produces undeniable axial force in the beams, which can significantly improve the flexural capacity of the beams. This phenomenon has not received enough attention. The unexpected super-strength of flexural capacity of RC frame beams may lead to the failure mode of strong columns and weak beams under strong earthquakes, resulting in structural collapse. In order to study the axial elongation effect of RC frame beams subjected to bending damage under earthquakes, the concept of beam elongation was firstly clarified, and the inevitability and composition of beam elongation were revealed from the mechanism. Based on the experimental study, the law of beam elongation was qualitatively analyzed. It was found that there is no comprehensive analysis model considering beam elongation effect at present. The research progress of the influence of beam elongation effect on seismic performance of structures and the possible problems caused by neglecting this effect were summarized and analyzed. Finally, it was pointed out that a series of basic studies on the   seismic failure modes and seismic performance of RC frame structures considering the effect of axial elongation of beam flexural damage were urgently needed to provide support for further improving the seismic ductility design method of frame structures. Finally, it was pointed out that a series of basic studies on the strong seismic failure modes and seismic performance of RC frame structures considering the effect of axial elongation of beam flexural damage were urgently needed to provide support for further improving the seismic ductility design method of frame structures.

Keywords:beam elongation; failure mode; seismic performance; numerical simulation; RC frame structure

*国家自然科学基金项目(51808087)，重庆科技学院校内科研基金项目（CK2016Z14, ck2017zkyb016），重庆市自然科学基金项目(cstc2018jcyjAX0695, cstc2018jcyjAX0052)。

通讯作者：罗文文，博士，讲师， Email: luowenwen326@163.com。