(中国建筑科学研究院有限公司， 北京 100013)

［摘要］现行《建筑结构荷载规范》（GB 50009—2012）风荷载计算公式基于规范所给定的基本振型形式进行推导，背景分量因子的部分参数则是基于规范振型直接积分获得，当实际振型与规范振型差异较大时，基于规范参数的计算风荷载可能与实际风荷载差异较大。从等效风振力法出发，针对结构沿高质量、受风面积、阻力系数不变情况，采用指数形式的振型，研究了高层及高耸建筑振型变化对顺风向风荷载的影响，并基于规范公式形式拟合了背景因子计算公式。研究表明：反映结构顶点位移的IΦ随振型指数增加而增加；但结构基底响应随着振型指数增加而减小；现行规范给定的振型函数可用指数函数替代，其中高层建筑振型指数为0.9；高耸建筑振型指数为1.5；当高层建筑振型指数低于0.9时，采用规范振型计算结果与实际结果相比偏小；当高层建筑振型指数高于0.9时，采用规范振型计算结果与实际结果相比偏大；对大部分超高层建筑，采用规范振型的顺风向风荷载比实际振型计算结果大，设计偏于安全。当高耸建筑振型指数低于1.5时，采用规范振型计算结果与实际结果相比偏小；当高耸建筑振型指数高于1.5时，采用规范振型计算结果与实际结果相比偏大。

［关键词］高层建筑；高耸建筑；振型指数；等效风振力；荷载规范；风振系数

中图分类号：TU311-3文献标识码：A文章编号：1002-848X(2021)07-0139-07

Influence of fundamental mode shape on downwind wind loads

YAN Yalin, CHEN Kai, TANG Yi

(China Academy of Building Research, Beijing 100013, China)

Abstract:The wind load calculation formula in current Loadcodeforthedesignofbuildingstructures (GB 50009—2012) is derived based on the basic mode shape given by the code, and some parameters of the background component factor are obtained based on direct integration of the fundamental mode shape of the code. When there is a big difference from the actual mode shape and the mode shape of the code, the calculated wind load based on the code parameters may be quite different from the actual wind load. Starting from the equivalent wind vibration force method, aiming at the constant high quality, wind area and resistance coefficient of the structure, the exponential vibration mode was used to study the influence of tall and high-rise building vibration mode changes on the wind load in the downwind direction. The background factor calculation formula was fitted based on the code formula. Research shows that: IΦ, which reflects the displacement of the apex of the structure, increases with the increase of the mode shape index; but the base response of the structure decreases with the increase of the mode index; the mode shape function given by the current code can be replaced by an exponential function and the mode shape index of tall buildings is 0.9; the mode shape index of high-rise buildings is 1.5; when the mode shape index of tall buildings is lower than 0.9, the calculated results using the code mode shapes are smaller when compared with the actual results; when the mode shape index of tall buildings is higher than 0.9, the calculated results using the code mode shapes are larger when compared with the actual results; for most super tall buildings, the downwind wind load of the code mode shape is larger than the actual mode shape, so the design is safe. When the mode shape index of high-rise buildings is lower than 1.5, the calculated results of the code mode are smaller compared with the actual results; when the mode shape index of high-rise buildings is higher than 1.5, the calculated result of the code mode is larger than the actual result.

Keywords:tall building;high-rise building;mode shape exponent;equivalent wind vibration force;load code;wind vibration coefficient

*国家重点研发计划项目（2017YFC0803300）。

作者简介：严亚林，博士，副研究员， Email：yanyalin@cabrtech.com；通信作者：陈凯，博士，研究员，Email：chenkai@cabrtech.com。