高层结构不规则项判别条件的探讨及建议

Discussion and suggestion on discriminant condition of irregular items in high-rise structures

随着复杂工程实践经验增加,以及结构力学模型愈加精细、计算软件功能显著提升,有必要对高层结构不规则判别条件进一步完善。针对《抗规》第3.4.3条定义的6个不规则类型,探讨了其力学概念以及当前执行上存在的一些问题,提出了相应的修订建议以供探讨。具体建议包括:采用考虑与不考虑偶然偏心下竖向构件剪力增大系数来判别扭转不规则;增加凸出部位宽度的限值用于凹凸不规则判别;增加楼层数的限值用于楼板局部不连续判别;增加楼层侧向刚度比的上限值用于侧向刚度不规则判别;增加不落地墙的截面面积占比或被托换柱的等效剪切刚度占比限值用于竖向抗侧力构件不连续判别;增加层间抗剪承载力比的上限值用于楼层承载力突变判别。根据所建议的不规则判别条件,对31个超限高层结构进行判别,相比根据《抗规》判别的结果,平面不规则数量明显减少,竖向不规则数量总体变化不大。

It is necessary to further improve the discriminant condition of irregular items in high-rise structures with the increase of practical experience in complex engineering, increasingly refined structural mechanics models and significant improvement of computing software function. Six types of irregular items defined in Section 3.4.3 of the Code for seismic design of buildings(GB 50011-2010) with its mechanics concepts and some problems in current implementation were discussed, and corresponding revision suggestions were proposed. The specific suggestions include: the torsion irregularity is discriminated by considering and not considering the shearing force increase coefficient of the vertical member under the accidental eccentricity;the limit of the width of the convex portion is added to distinguish concave and convex irregularity;the limit of the number of stories is added to distinguish slab local discontinuity;the upper limit value of the lateral stiffness ratio between stories is added to distinguish the lateral stiffness irregularity;the proportion limit of the cross-sectional area of the non-falling wall or the equivalent shear stiffness of the underpinned column is added to discriminate the discontinuity of the vertical force resisting members;the upper limit value of shear bearing capacity ratio between stories is added to determine the sudden change of story bearing capacity. According to the proposed discriminant conditions, 31 out-of-code high-rise structures were discriminated. Compared with the discriminated results of Code for seismic design of buildings(GB 50011-2010), number of plane irregularities was significantly reduced, while the vertical irregular quantity had little change.