Measured imperfections in six thin-walled steel tubes

The structural behaviour of thin-walled members is often extremely imperfection sensitive. For many types of such members only little information of the exact nature of the present imperfections is available. A method of measuring imperfections of circular cylindrical members has been developed and was used to measure six thin-walled tubes. The method is simple to implement in a laboratory environment yet very accurate. Numerical methods to process the measurements into three-dimensional imperfection maps and an algorithm to distinguish between significant imperfection patterns from measurement ââ"šÂ¬Ã…"noiseââ"šÂ¬Ã‚ have been derived. Results of the measurement of these six tubes are presented in this paper. Conclusions about the nature of the imperfections are drawn and imperfection amplitudes for the six tubes are given.