SHEAR STRENGTH OF WELDED ALUMINIUM ALLOY PLATE GIRDERS

Aluminium alloys are used in a variety of structural engineering applications, such as transportable and lightweight bridges, due to their high strength/weight ratio and durability. However, the heat of welding may reduce their strength significantly, and necessitate the inclusion of strength reduction factors in design calculations. Experimental studies of the ultimate shear resistance of welded aluminium alloy plate girders have indicated that failure generally occurs due to rupture of the heat-affected welded web boundary, during the development of a typical shear failure mechanism. Theoretical procedures for predicting ultimate shear resistance, based on tension-field theory and including material strength reduction factors to allow for welding, are now incorporated in BS 8118: 1991: Part 1. However, when compared with available test data, theoretical predictions in accordance with the over-simplistic recommendations in BS 8118 appear unduly conservative. Available test results for the ultimate shear resistance of welded aluminium alloy plate girders are reviewed and discussed. An improved theoretical procedure for predicting ultimate shear resistance, similar to that incorporated in BS 8118 but retaining the rigour of the original tension-field theory, is presented which shows consistent and significantly improved correlation with the test data. (A)