框架-核心筒混合结构整体稳定性研究

Study on overall stability of frame-corewall mixed structure

为了研究高层与超高层框架-核心筒混合结构的整体稳定性能,推导了框架-核心筒简化力学模型,考察结构高度与抗震设防烈度的影响。基于ABAQUS有限元软件、简化方法和GB 50017—2017《钢结构设计标准》,分别对框架结构、筒体结构和框架-核心筒结构的屈曲模态、屈曲荷载和屈曲因子进行分析,考察屈曲因子与二阶效应的关系。分析结果表明:框架-核心筒结构整体失稳形态为弯剪型,未发生局部楼层或个别构件失稳的情况;屈曲变形主要分布在中上部楼层,屈曲变形的范围显著大于框架与核心筒分体模型的;由于框架与核心筒之间的互相支撑作用,框架-核心筒结构整体模型的屈曲荷载高于框架结构与筒体结构分体模型屈曲荷载之和;考虑二阶效应后,在侧向均布荷载作用下,框架-核心筒结构上部楼层层间位移角的增幅保持不变;基于屈曲因子与二阶效应的相关性,可以通过屈曲因子直接对结构的整体稳定性能进行判断。框架-核心筒结构中,其框架的屈曲荷载最大可超过纯框架结构屈曲荷载的10倍;可以根据框架-核心筒结构中框架屈曲荷载的增大系数,对有侧移框架柱的计算长度系数进行修正;由简化方法得到框架-核心筒结构的屈曲荷载与有限元法计算结果具有较好的一致性,可用于框架-核心筒结构屈曲荷载的初步估算。

In order to study the overall stability of the high-rise and super-high-rise frame-core wall hybrid structures,a simplified mechanical model of the frame-core wall was derived to investigate the influence of structure height and seismic fortification intensity.Using ABAQUS finite element software,simplified methods and GB 50017-2017‘Standard for design of steel structures’,the buckling mode,buckling capacity and buckling factor of the moment frames,core walls and frame-core walls were analyzed.Subsequently,the relationship between the buckling factors and the second-order effect was investigated.The analysis results show that the overall instability of the frame-core wall structures is a bending-shear type,and there is no buckling of local stories or individual components.The buckling deformation of the frame-core wall structures is mainly distributed in the middle and upper stories of the towers,and the range of buckling deformation is significantly larger than that of the frame model and the core wall model.Due to the interactive support between the frame and the core wall,the buckling capacity of the overall model of frame-core wall structure is higher than the sum of the stable bearing capacity of the frame model and the core wall model.After considering the second-order effect,the increment of inter-story displacement drift ratio on the upper stories of frame-core wall structure remains unchanged under uniform lateral load.Based on the correlation between the buckling factor and the second-order effect,the overall stability of the structure can be judged by the buckling factor directly.The maximum stable bearing capacity of the moment frames of the frame-core wall structures can exceed 10 times that of the moment frame structures.The calculated length coefficient of the columns within sway frames can be corrected according to the magnification factors of frame buckling loads.The simplified method shows that the buckling capacity of the frame-core wall structure is in good agreement with the analysis results of the finite element method,and can be used for the preliminary estimation of the buckling capacity of the frame-core wall structures.