汶川地震钢筋混凝土框架结构震害及对策

Seismic Damage and Design Concept from the Buildings of RC Frame Structure in Wenchuan Earthquake

汶川大地震造成了部分钢筋混土框架结构的严重破坏和倒塌,震害包括结构的整体倒塌、部分倒塌、薄弱层倒塌、底层柱的柱顶和柱底的弯曲破坏、短柱的剪切破坏、框架梁端的弯曲破坏等等;此外原先抗震设计时不被注意的楼梯出现受拉破坏,有的甚至被拉断;填充墙是框架结构破坏严重的非结构构件。框架结构这些震害产生的原因多种多样,如实际地震影响烈度大大超过设计设防烈度、建筑的施工质量问题、设计不合理(刚度突变,强梁弱柱),等等。在对倒塌破坏的框架的震害进行深入分析后,本文提出了解决框架结构抗倒塌的方法:加强柱的抗震设计、适当布置抗震墙、采用隔震或消能减震技术。楼梯设计时应考虑地震下楼梯受力情况,采用刚性连接时,要求计算出楼梯地震效应,并进行配筋;楼梯一端与结构采用滑动连接时,可消除楼梯地震作用下的内力,设计时可不考虑地震影响;加强结构填充墙抗震性能,确保罕遇地震下不致倒塌伤人。

Wenchuan 5.12 earthquake caused severely damage in RC frame. In this paper, many kinds of damage on RC frame structure are introduced, such as the integral structure collapse, soft story collapse, bending damage at the bottom and/or the top of columns, shear failure in short column, etc. The stairs without seismic design appear pulling damage and some of them are even pulled down. Filling wails are also badly damaged. The causes of the damage in RC Frame under earthquake are that earthquake intensity, the construction quality, the unreasonable design such as the mutation in vertical stiffness and the strong beam and the soft column, etc. After a thorough analysis, the anti collapse methods of RC frame structure are proposed： strengthening the aseismic ability of the column in design, adding shear walls in RC frame and using base isolation or energy dissipation technology. Earthquake should be considered in stair design if stairs connect with the structure directly, but if setting sliding link between stair and structure, the effect of earthquake could be neglected. Strengthening the antiearthquake performance of filling wall could ensure no collapse happening during severe earthquake.