基于附加变形控制的框架结构抽柱扩跨分析  

Analysis on Cutting Column to Extend Span of Frame Structure Based on Controlling of Additive Deflection

作　　者：敬登虎[1] 曹双寅[1] 

机构地区：[1]东南大学混凝土及预应力混凝土结构教育部重点实验室,南京210096

出　　处：《建筑科学》2009年第7期56-60,55,共6页Building Science

摘　　要：框架结构为了满足大空间使用功能的改造,需要抽去部分框架柱,导致原有结构的传力路径发生变化,可以采用对原框架梁进行加固形成转换梁。当转换梁上部对应位置还有框架梁柱时,由于转换梁受到上部荷载的作用,跨中可能会产生一定的竖向挠度,造成上一层框架梁的端部出现类似不均匀沉降的附加变形,从而使得一些梁端的弯矩和剪力都不同程度的增加。该附加变形引起的内力增幅不容忽视,其大小主要与附加变形、框架梁的截面尺寸、弹性模量、跨高比等参数有关。为了使附加内力不影响既有原先实际结构的安全性,转换梁设计的主要控制指标应是允许附加变形。结合南京名人城市酒店裙楼4层(共6层)会议室的抽柱扩跨改造,即将原8.0m×8.2m的柱网变为16.0m×16.4m的实际问题。就如何考虑附加变形的控制给出算例,后期的检测结果表明该分析方法是合理可行的,可供类似工程借鉴。To obtain large space for other use in the frame structure, parts of columns need to be removed, resulting in a transition of the structure due to changing of load path. One of the effective ways is to strengthen the original beam into the transform girder. When there are some beams and columns on the transform girder, the same additive deflection as differential settlement happens on the upper beams due to vertical deflection of girder under external loads, which will result in raise of moment and shear force located in the beam ends to a certain extent. The additive internal force due to additive deflection can＇t be ignored, that is related to its additive deflection, the section dimensions, elastic modulus, and the ratio of span to height for the beam and so on. In order to guarantee the additive internal force has no influence on the safety of existing structure elements, the control of the additive deflection is a key target during the design of transform girder. Based on an actual retrofit project on cutting column to extend span of meeting room located in the fourth-storey （a total of six storeys） in Nanjing Mingren City Hotel, i.e., a practical problem about changing the original grid of 8.0m × 8.2m into that of 16.0m × 16.4m should be solved. The example mainly introduces how to consider the control of the additive deflection, and the subsequent testing results show the analysis in this paper is reasonable, which can be referred by similar projects.

关 键 词：框架结构 抽柱 转换梁 附加变形 

分 类 号：TU375.1[建筑科学—结构工程]