Comparison of Wind Tunnel Test Data for Low-Rise Buildings with Main Wind Force Resisting System Design Procedures

S M Ashfaqul Hoq,Johnn P Judd

doi:10.3390/buildings11080342

Abstract

The adequacy of the directional and envelope procedures for the design of the main wind force resisting system is not well understood. The purpose of this study is to evaluate the directional and envelope procedures based on wind tunnel test data for a set of low-rise enclosed buildings with gable-shaped roofs in open terrain (Exposure C). The base shear force and the conditional reliability index are used to determine the adequacy of the procedures. The base shear was compared to the design base shear in each direction based on the horizontal component of the wind load on the wall and roof. The reliability index, β conditional on the occurrence of the design wind speed was computed for a range of system capacities. The main findings are (1) the directional procedure produced a larger design base shear compared to the envelope procedure, primarily due to the difference in external pressure coefficients, (2) the directional procedure provided a higher β, and (3) the envelope procedure provided a β that did not meet the standard target β equal to 3.0 for the main wind force resisting systems with low variability in capacity, but neither procedure met the standard target β for the main wind force resisting systems with high variability in capacity.

Highlights

The design of the main wind force resisting system (MWFRS) in buildings is a basic part of structural engineering practice, but currently there is no consensus on the appropriate procedure to determine MWFRS design wind loads for low-rise buildings
The MWFRS design wind loads for a set of low-rise gabled roof buildings in open terrain (Exposure C) were calculated using the directional and envelope procedures described in ASCE 7–16
The design base shear in each principal direction was compared with the calculated base shear from wind tunnel test data, and the reliability index, β conditional on the occurrence of the design wind speed, was determined based on a demand-to-capacity ratio equal to 1.0 and a range of variability in the MWFRS capacity

Summary

Introduction

The design of the main wind force resisting system (MWFRS) in buildings is a basic part of structural engineering practice, but currently there is no consensus on the appropriate procedure to determine MWFRS design wind loads for low-rise buildings. In the directional and envelope procedures, design loads are determined analytically using pressure or force coefficients that are primarily based on data from wind tunnel tests of generic building models. In the wind tunnel procedure, design loads are determined experimentally in a wind tunnel using pressures measured on the surface of a small-scale model of the actual building that is being designed. The wind tunnel procedure is primarily used for flexible structures, irregularly shaped buildings, buildings shielded by adjacent buildings, or other structures that require special considerations, whereas the directional and envelope procedures are used for routine design. This study focuses on the directional and envelope procedures

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