SAFETY OF POST-FIRE STRENGTH CAPACITY PREDICTION IN BOLTED STEEL JOINTS

Abstract

Analytical study of the reliability of a typical bolted double lap joint is presented. Evaluation of the experimental formulation of the strength is carried out using First Order Reliability Method. Results obtained showed that there is a significant capacity reduction of the joint as the residual strength index, RSI, of the connection decreases.  Five failure modes which depend on the embedding strength of the steel plates and/or bolts were used to obtain the joint capacities; while the failure due to bearing of plates at the joint was found to be the least reliable. It was observed that increase in member thicknesses, bolt diameters, number of bolts and end/edge distances enhance the safety levels but may not be economical. However, reduction or decrease in any of the above mentioned parameters proved otherwise. More so, safety indices as obtained indicate that steel bolted joints can be rehabilitated and re-used after fire with ease.