Design guide for wind loads on unclad framed building structures during construction

Document Status

Current

Supplement

Civil & Structural Supplement

Series

Report

Abstract

Framed building structures can be more susceptible to wind forces during construction than when completed. The wind forces on the unclad structures can be comparable to those when the building is clad but there is often little dead weight to counteract tensions that may occur at joints and foundations due to uplift. Force coefficients calculated by the method of the UK wind code for multi-framed structures are known to be very conservative, particularly when the number of frames is large. This guide has been developed to provide a quick but realistic assessment of the wind forces in these conditions. The guide covers choice of the design wind speed for temporary conditions, and provides up-to-date guidance on drag forces on multiple frames. Graphs of force coefficient against solidity ratio and number of frames are provided for rectangular buildings and guidance is given on the application of these curves to practical structures. In some cases the general height of surrounding buildings and direct shielding by specific upwind buildings can substantially reduce the wind loads on downwind building frames. In some circumstances it may be considered worthwhile to take account of these effects in temporary stability calculations, and some recommendations for their assessment are given in the Appendix.

Author

Willford, M. R. and Allsop, A. C.

Subjects

• Special subject areas
• Building structure
• Structural/mechanical factors
• Wind loads
• Building systems/frame

Publisher History

BRE is a building science centre that generates new knowledge through research. This is used to create products, tools and standards that drive positive change across the built environment. BRE helps its government and private sector clients meet the significant environmental, social and economic challenges they face in delivering homes, buildings and communities. BRE is owned by the BRE Trust, a registered charity. The Trust uses the profits made by the BRE companies to fund research and education that advances knowledge of the built environment.