How have full-scale measurements improved the reliability of wind-loading codes? Dick Marshall's contribution to full-scale measurements of wind effects

摘要

The contribution that full-scale measurements have made to wind-loading codes is discussed. The early work of Dick Marshall, on the measurements of wind loads on mobile homes, is a good starting point as it was one of the earliest measurements on full-scale buildings, using modern data-logging methods and incorporating the vigorous approach of quantifying the approach flow and defining reference pressures. He also addressed the problem of load transfer, which is an essential part of the wind-loading problem. This paper makes no attempt to review full-scale measurements, but sets out to identify the component parts of the wind-loading procedure where full-scale measurements play an essential role. This recognises that the wind-loading problem arises because buildings are constructed in the very turbulent part of the atmospheric boundary layer, and that quantifying and measuring the effect of turbulence is an essential part of the study. This is not only important in full-scale measurements but is crucial in simulated model studies. It is argued that only by a better understanding of the atmospheric boundary layer will we be able to develop codes that have a rational basis and can be accepted in a single form across international borders. It is through this approach that the debate over pressure coefficient values can be harmonised. It is acknowledged that most of the information relating to pressure coefficients in wind-loading codes is derived from wind-tunnel studies, which have not always been conducted in realistic simulations. The main impact of full-scale measurements on wind-loading codes is likely to be through comparative full-scale and wind-tunnel studies, in correctly simulated boundary layers, on geometrically similar buildings. The lessons we learn can then be applied more generally to results from model studies, and can similarly be applied to computational methods of calculating wind loads, an approach that is likely to become more prevalent as CFD develops.