钢筋混凝土框架结构强柱弱梁设计方法的研究

STUDY ON WEAK BEAM-STRONG COLUMN DESIGN METHOD OF RC FRAME STRUCTURES

针对汶川地震中框架结构大多未能实现"强柱弱梁"的问题,结合国外几个代表性规范的有关规定和文献资料,对我国规范"强柱弱梁"设计方法存在的问题进行了分析,指出影响"强柱弱梁"的主要因素包括柱梁抗弯承载力比、梁端钢筋超配、现浇楼板和材料强度的离散性等。根据"强柱弱梁"机制的结构受力特点,采用合理简化结构模型,通过20条强震记录的弹塑性时程分析,对柱梁抗弯承载力比需求η及其分布进行了分析研究,指出柱梁抗弯承载力比需求η随地震强度的增加而增大,并根据分析结果给出了不同抗震等级框架结构柱梁抗弯承载力比的设计建议。

The prefered ＇strong column-weak beam＇ mechanism is not oberseved in most buildings in 5.12 Wenchuan Earthquake.The ＇strong column-weak beam＇ design method in Chinses code are reviewed.Referring to international seismic design codes and related literatures,it is found that the damage pattern is affected by the following factors： the ratio of column-to-beam strength,over-reinforcement in the beam,contributions of the cast-in-site concrete slabs,scattering of material strength.Nonlinear dynamic analysis of RC moment-resisting frames excited by 20 strong ground motions are carried out to study the required ratio of column-to-beam strength and its heigh-wise distribution.It is found the required ratio of column-to-beam strength increases with the increase of earthquake intensities.Finally,some suggestions are given to ensure the realization of ＇strong column-weak beam＇ mechanism.