高烈度区近断层RC框架-核心筒高层结构隔震设计关键参数取值

Critical design parameters of seismically isolated RC frame-core tube tall buildings located in near-fault regions

以2栋设防烈度为8.5度、近断层且具有不同高度的钢筋混凝土框架核心筒高层隔震工程案例为原型,考虑不同隔震设计方案(核心筒下沉隔震方案和整体±0隔震方案)的影响.基于精细有限元模型,研究了屈重比对该类结构减震系数和隔震层位移的影响规律,并以此为基础对近场影响系数的取值开展了初步研究.结果表明,减震系数和隔震沟尺寸要求分别决定了RC框架-核心筒高层隔震结构屈重比的上限值和下限值,适用于该类结构的合理屈重比的取值范围为2%~3%;近场和远场地震动作用下的结构响应分布特征一致,但近场下的结构响应明显强于远场下的结构响应;当断层距小于5 km时,近场影响系数可适当放宽至1.25.

Based on two reinforced concrete(RC)frame-core tube tall buildings located in near-fault regions with the seismic intensity of 8.5 degree and different heights,two seismically isolated schemes i.e.traditional base-isolated scheme and partially basement-isolate scheme were designed.Then,the influences of yield ratio of the isolation system on the seismic decrease coefficient and the maximum bearing displacement were investigated using the refined finite element model.Furthermore,the appropriate value of the near field influence coefficient was studied.The studies show that the rational range of the yield ratio of the isolation system is recommended as 2%to 3%.The structural responses under near fault ground motions and ordinary ground motions exhibite identical distribution characteristics.However,the structural responses under near fault ground motions are much severer than those under ordinary ground motions.The near field influence coefficient with a value of 1.25 is suggested for the seismically isolated design of RC frame-core tube tall buildings when the corresponding closet distance to rupture plane is less than 5 km.