Buckling strength of welded and non-welded aluminium members.

High strength aluminium alloys when welded suffer a local loss of strength due to heat-affected zone (HAZ) effects. The influence of such localised strength loss on structural behaviour of columns, beams and beam-columns is studied using numerical technique. Two programs INSTAF and BIAXIAL, previously developed for the use of steel structures, have been modified to incorporate the special features of the aluminium problem. The general inplane behaviour of aluminium frames or members is studied by using program INSTAF. The general 3-D behaviour of aluminium members is simulated by the program BIAXIAL. Attention is given to the representation of the nonlinear stress-strain behaviour of aluminium, in particular, its representation in a form suitable for incorporation into numerical processes. Results are presented for a wide range of problems to illustrate the severity of the HAZ effect on the load carrying capacity of structural members.