APPARENTLY INCIDENTAL street furniture could have major or even disastrous effects on bridge behaviour when exposed to high winds, a busy meeting at the ICE heard recently.
Bridge engineer Chris Davis from consultant Mott MacDonald said that all the objects on a bridge could cause vortex formation. Amplitude response might prove to be critically affected by smaller objects, especially when considering the current trend for ultra slim, non-symmetrical footbridges.
Davis called for engineers and wind tunnel specialists to work more closely, with open minds and an active open dialogue. He was backed from the floor with claims that wind tunnel testers too often gave answers only to the questions asked of them and not what they should have been asked by the engineer.
But there is plenty to be extracted from tests, the meeting had already heard.
Professor Nick Cook from Bristol University's department of aerospace engineering outlined a new data protocol for wind tunnel tests. The system handles time series data in such a way that a designer can extract many variations of information required from one single test run.
Cook claims the protocol is flexible enough to 'work the way you want, not tell you the way it wants you to work' Cook urged that data never be aimlessly discarded from test runs because of what can further be extracted from it. He also urged further work to develop the reliability of wind tunnel techniques.
Andrew Allsop, a leading wind engineer from consultant Arup, said that his firm currently undertakes 30-40 wind tunnel tests a year. 'And there is scope to do plenty more' he added. He envisaged a continued increase in use of the tests as advances in technology and cost reduction make the technique available for engineers even on medium sized projects.
Allsop highlighted the lack of dependable Computational Fluid Dynamic (CFD) systems and the need for a greater knowledge of damping effects on built structures in the future.