某超高层办公楼结构超限设计分析

Analysis on the structural over-limit design of a high-rise office building

某35层办公楼项目结构高度178.5m,采用框架-核心筒结构,其中26层以下部分框架柱采用钢骨混凝土柱。结构整体平面扭转不规则、相邻层受剪承载力比不规则及局部存在斜柱,抗震性能目标综合确定为C-。根据动力弹塑性分析结果,结构X、Y向在罕遇地震作用下的最大层间位移角分别为1/285、1/257(规范限值1/171)。外框柱在大震下局部产生轻微损坏或轻度损坏(集中约顶部13层),核心筒混凝土受压损伤较小,处于弹性状态;局部剪力墙(4~9层、13~14层)混凝土剪切应变等级达到4或5级,分布于核心筒外墙连梁洞口附近。针对结构上部斜柱节点传力机制的细部分析结果表明,斜柱节点在最不利荷载组合作用下整体变形较小,节点区域混凝土工作状态良好,钢筋最大应力计算值未超材料强度。综合分析结果的基础上,针对结构不规则项或薄弱部位提出了相应的加强措施,可为类似工程设计提供参考。

The structural height of a 35-storey office building project is 178.5m,and the frame-core tube structure is adopted.Some frame columns below the 26th floor are steel reinforced concrete columns.The overall plane torsion of the structure is irregular,the shear bearing capacity ratio of adjacent floors is irregular,and there are inclined columns locally.The seismic performance objective is comprehensively determined as C-.According to the results of dynamic elastic-plastic analysis,the maximum inter-story displacement angles of the structure in X and Y directions under the action of rare earthquakes are 1/285 and 1/257 respectively(the code limit value is 1/171).The outer frame column is partially slightly damaged or slightly damaged(concentrated on the top 13 floors)under the strong earthquake,and the core tube concrete is slightly damaged under compression and is in elastic state.The concrete shear strain grade of local shear wall(4~9 floors,13~14 floors)reaches 4 or 5,which is distributed near the coupling beam opening of the outer wall of the core tube.The mechanical performance of the upper inclined column joint of the structure is analyzed in detail by finite element method.Under the most unfavorable load combination,the overall deformation of the inclined column joint is small,the concrete in the joint area is in good working condition,and the calculated value of the maximum stress of the reinforcement does not exceed the material strength.Based on the comprehensive analysis results,corresponding strengthening measures are proposed for the irregular items or weak parts of the structure,which can provide reference for similar engineering design.