大跨单层球面网壳的风振系数及其参数分析

本文针对某工程的单层网壳结构方案,采用其风洞试验数据,通过有限元方法在时域内进行三维风振分析,获得了钢网壳24个风向角下的竖向风振系数值,并通过对试验数据和计算结果的分析,确定了风荷载的不利风向角。同时考虑到钢网壳在风荷载作用下,不仅产生竖向风振,并且存在水平向风振,计算了不利风向角下的顺风向和横风向风振系数。进一步进行了该网壳结构在各种参数工况下风振系数的参数影响分析。结果表明:风振系数随风向角变化敏感,在抗风设计时应该考虑到这一规律;斜杆的使用大大减小了单层球面网壳的风振系数值;边界约束条件对风振系数的影响不大;结构阻尼比对竖向风振影响比水平风振响应更明显,阻尼比增大,风振系数有一定程度的减小。这些结论可为单层网壳结构抗风设计、防灾分析提供借鉴。

Wind load factor and parametric analysis of long-span single-layer spherical reticulated shell

Using three-dimensional FEM,wind-induced dynamic response of a project designed with single-layer spherical reticulated shell scheme,was analyzed to obtain vertical wind load factors of 24 wind angles.The worst wind angle was identified by using data from wind tunnel test and the analysis.Due to the fact that there exists not only vertical wind-induced vibration but also horizontal wind-induced vibration,leeward and crosswind load factors are calculated at disadvantage angles.The results of parametric analysis for different cases indicate that wind load factor varies obviously with wind angle,which should be considered in wind resistance design.For single-layer spherical reticulated shell,diagonal braces can significantly reduce wind load factor,however the boundary conditions have little effect.The wind load factor has some reduction as the damping ratio increases.The damping ratio has a larger effect on vertical wind load factor than horizontal wind load factor. These conclusions contribute to the wind-resistance design and disaster prevention analysis of reticulated shell structures.