钢筋混凝土框架顶部钢结构加层层数对结构抗震性能影响研究

Influence of story number of steel structure added to top of RC frame on seismic behavior of the frame

以工程实例为背景,研究了一个4层钢筋混凝土框架的顶部增加了不同层数的钢框架后,结构抗震性能指标的变化规律,包括结构周期和频率,以及多遇地震下楼层的最大水平位移、层间位移角、层间剪力等。结果表明,可以根据不同加层设计方案相应的最大层间位移角确定最大加层层数;加层结构层间位移角最大值常出现在加层结构顶部第2层,而原结构下部某一层位也可能在加层后演化成整体结构的薄弱层。加层越多,底层层间剪力值反而越小,这一规律可以为被动抗震设计提供一种新思路。

Based on a practical project,the seismic performance indices of a 4-story reinforced concrete frame with different added stories of steel frame constructed on its top were investigated,including vibration period,frequency,and seismic response under frequently occurred earthquake,such as inter-story maximum horizontal displacement,inter-story maximum horizontal drift angle,inter-story shear force and so on.It reveals that the maximum additional number of stories may be determined by the inter-story maximum horizontal interstory drift angle.The maximum horizontal interstory drift angle often comes into being at the second floor from the top of the structure,and at the same time,a certain story in the original structure may evolve into a weak story which has to be reinforced.However,with the increasing of additional stories,the total shear force in the bottom story decreases,which leads to a new seismic resistance design concept.