某大底盘双塔结构超限设计

Structural Design of a Twin-tower Beyond the Code Limit

本工程由于建筑平面布局原因,塔楼与裙房之间无法设置防震缝,两塔楼平面不对称,因此成为超限高层结构。在结构的超限设计中,通过对单塔及整体模型的分析对比,以及对二道防线设计的框架剪力调整进行了分析研究,确定了包络设计的原则,对于大底盘以上楼层及其在裙房的投影范围设计取整体模型计算结果,对于大底盘裙房范围内框架设计时采用整体模型和裙房单塔模型配筋结果进行包络设计。通过对塔楼连接薄弱部位的分析,双塔连接的位置及塔楼与裙楼连接的区域应力较大,采取加大板厚及楼板配筋的加强措施。通过弹塑性时程分析验证了结构的变形及薄弱部位,核心筒墙体在底部加强区域出现不同程度的受压损伤,底部楼层沿平面长向的墙体及核心筒角部受压损伤较为严重,通过提高底部框架及剪力墙抗震构造措施等级至特一级,提高底部核心筒外墙水平及竖向分布筋配筋率并设置过渡层,保证了结构设计的合理性及安全性。

Due to the architecture plan layout,a seismic joint cannot be set between the tower and the podium,and the two towers＇ plans are not symmetry,so the structure turns into a beyond the code limit structure. According to the comparison of the single tower model and the whole structure model during the structural design process,the research on the adjustment of the frame shear for the second line of defense,a principle of envelope design is defined; for the tower above the podium and the shadow area of it,the calculation result of the whole model should be used; for the frame design of the podium,the reinforcement envelop of the whole model and the separated model should be used. The analysis of the weak parts shows that the stress of the connection area of the two towers and the podium is quite large,so the thickness of the slab and the amount of the rebar should be enlarged. The elastic-plastic time history analysis is carried out to verify the deformation and the weak parts,some damages of compression are occurred in the wall of the lower reinforced stories,especially in the wall along the long X axis and the wall near the corner. By enhancing the the construction seismic grade of the frame and shear wall in the lower stories to special first,increasing the distributed rebar ration in the outside wall of the core in the lower stories,and setting transition stories,the rationality and security of the structure are ensured.