高层建筑结构的扭转反应控制及工程实例

Control of torsional response of tall building structure and some actual applications

结构在地震中的扭转反应控制是高层建筑抗震设计中的一个重要内容。《高层建筑混凝土结构技术规程》(JGJ 3—2002)主要通过考虑偶然偏心和控制周期比、位移比来控制结构的扭转反应。控制扭转的技术措施主要分两类:一是调整质量中心和刚度中心的偏心;二是增大结构的抗扭刚度或者适当减小结构的抗侧刚度。根据理论分析及实际工程经验,得出如下结论:抗震设计时宜取考虑偶然偏心和考虑双向地震两者中不利结果进行设计;宜控制结构的前两个振型以两正交主轴方向上的平动振型为主;对于平面狭长的框架结构,加大两边榀的框架梁比加大边榀的柱在提高结构的抗扭刚度上能起到更好的效果;剪力墙结构可以通过加大外圈连梁高度,角窗部位增设暗梁来提高结构的抗扭刚度。

Control of torsional responses of tall buildings is an important aspect in seismic design.In 'Technical specification for concrete structure of tall building',the torsional response is mainly controlled by measures that consider accidental eccentricity,controlling period ratio and displacement ratio.Two types of measurements can be used to control torsion response: to adjust eccentricity of mass center and stiffness center,and to enhance torsion stiffness or reduce lateral stiffness of the structure.On the basis of theoretical analysis and practical experiences,the following conclusions are drawn.Seismic design of tall buildings should be based on the adverse result which is obtained by considering accidental eccentricity or 2-dimensional earthquakes.The first two vibration modes should be translational in two orthogonal axes.When the plane of the structure is long and narrow,the better way to enhancing torsion stiffness of the structure is better to increase the beam section of the two side trusses than to increase column section.The torsion stiffness of shearwall structure can be efficiently improved by enlarging coupling beam height of outer edge and adding a beam-in-slab to connect the shear walls that was broken by a window on the corner.