砌体与钢筋混凝土框架平面混合结构抗震性能评估及加固方法研究

Research on seismic performance evaluation and strengthening method of planar mixed structure by masonry and reinforced concrete frame

我国规范中对既有建筑中存在的砌体与钢筋混凝土框架平面混合结构的抗震验算及加固方法未详细规定。对此类结构在水平地震作用下的受力机理以及水平剪力分配计算方法进行了分析,此类结构在水平地震作用下水平剪力主要由砖墙承担,砖墙与框架不能同时达到承载能力极限状态,不能有效协同工作,总体抗震性能较差。在抗震验算时,对于砖墙应考虑其承担全部水平地震剪力,而对于框架应按砖墙严重开裂后的有效刚度进行剪力分配。结果表明,通过设置一定数量的钢筋混凝土剪力墙将其加固为砖墙-混凝土墙组合结构具有良好的效果,砌体承担的水平剪力明显下降,结构具有多道抗震防线,抗倒塌能力得以大幅提高,但应控制钢筋混凝土墙高宽比在合理的范围内,并设置可靠的基础以保证由墙肢受弯承载力起控制作用。

The seismic checking and reinforcement methods of planar mixed structure by masonry and reinforced concrete frame in existing buildings are not specified in China’s code.The force mechanism and the calculation method of horizontal shear force distribution of this kind of structure under horizontal earthquake action were analyzed.The horizontal shear force of this kind of structure under horizontal earthquake action is mainly borne by the brick wall.The brick wall and the frame cannot reach the ultimate state of bearing capacity at the same time,and cannot work together effectively,and the overall seismic performance is poor.In the seismic checking,the brick wall should be considered to bear all the horizontal seismic shear force,and the frame should be distributed according to the effective stiffness of the brick wall after serious cracking.The results show that by setting a certain number of reinforced concrete shear walls,the structure would be reinforced to be brick and concrete wall composite structure,which has good effect.The level of the masonry bear shear decreases obviously,the structure has a multichannel seismic lines,and collapse resistance can be greatly increased.But the height-width ratio of reinforced concrete wall should be controlled in a reasonable range,and a reliable foundation is set to ensure that the bending capacity of the wall limb plays a controlling role.