Displacement measurement in studies of steel T-stub connections

Traditionally steel and composite steel and concrete beam to column joints at the fire limit state are assumed to behave in the same way as used in the design at ambient temperature, that is a joint that is assumed to be pinned at ambient temperature is also assumed to be pinned at elevated temperatures. Recent fire rests on the eight-storey steel frame building at Cardington suggest that joints, which are assumed to be pinned at ambient temperature, can provide significant levels of both strength and stiffness at elevated temperature. In steel structures, the behaviour of joints, between beams and columns may be investigated by separate consideration of the various components. which comprise the joint. However, measurement of the distorted profiles of components can be problematic. This paper describes thr use of an image acquisition and processing technique for the measurement of deformations in steel T-stub connections, representing the tension component in a steel joint. Although the application has been developed to solve the problems associated with measuring deformations in tests conducted at high temperatures, it also offers advantages over conventional techniques at ambient temperatures. (C) 2001 Elsevier Science Ltd. All rights reserved.