Experimental investigation of wind-induced internal pressures in nominally sealed building structures

Abstract

The action of internal pressure cannot be neglected in wind-resistant design of large-span structures, high-rise buildings, and low-rise residential buildings. In this study, the internal pressure characteristics were first measured in still air in a completely closed building structure without any leakage. Then a series of wind tunnel tests were conducted to study the probability density distribution characteristics of the internal pressure responses in a nominally sealed building with background leakage. The mean and peak internal pressure responses associated with different background leakage distributions and wind directions were further investigated, and the experimental results were compared with those suggested by the Chinese wind load code GB50009-2012. The results indicated that the internal pressure in the completely closed building was non-stationary, and varied significantly when collected at different time points. Furthermore, a period of about 24 h was observed from the measured time history of internal pressure over 9 d. The internal pressure in a nominally sealed building structure nearly fitted a normal Gaussian distribution. When background leakage was uniformly arranged on the surface of the building, the mean internal pressure coefficient remained unchanged with increasing background leakage, varying within the range from −0.15 to −0.14, indicating lower magnitudes than the value of −0.2 suggested by the Chinese wind load code. The minimum negative peak internal pressure coefficient was −0.255 when the peak factor was 3.5, indicating a lower magnitude than the value of −0.326 calculated in the Chinese wind load code.

中文概要

目的:在确保模型气密性绝对良好的前提下,通过设置 不同的背景泄漏,详细研究不同背景孔隙率和风 向角下的平均和峰值内压水平,为工程结构抗风 设计和规范修订提供指导和依据。

创新点:首次探究了完全封闭结构的内压特征,并在此基 础上系统研究了不同背景孔隙率和风向角下名 义封闭结构的风致内压变化规律。

方法:1. 在静态空气中进行压力测试,获得完全封闭结 构的内压特性(图6~9)。2. 在完全封闭结构的表 面开不同的孔隙;通过多参数风洞试验(图3 和 表1),获得名义封闭结构的平均和峰值风压变化 特征(图14~18),并与中国建筑结构荷载规范 (GB50009-2012)进行对比分析。

结论:1. 完全封闭结构的内压呈非平稳状态,长达9 d 的观察结果表明内压呈现一定的周期性。2. 在均 布背景孔隙下,平均内压系数仅在−0.15~−0.14 范围内波动,且低于中国建筑结构荷载规范的取 值−0.2。3. 当峰值因子g 取3.5 时,最高负极值 风压系数为−0.255,低于由规范计算得到的峰值 内压系数−0.326。