Evolution of plastic damage in welded joint of steel truss with pre-existing defects

Experimental analyses are made for the local damage evolution of structural response for a steel truss structure with pre-existing defects in welded joints. Employing a scaled down specimen of the steel truss present in decks of long-span bridges, the photoelastic coating method is adopted to obtain data information on local hot-spot strains near the welded joints while strain and displacement gauges are employed for collecting information on the response of the global structure. Initially, a finite element model of the steel truss is established for the purpose of pre-experimental evaluation. Defects such as holes and a crack are pre-existing near the welded joints. The local plastic damage evolution is captured by photoelastic images and evaluated in relation to the global structural mechanical performance. Local defects tend to affect the weldment details and structural rigidity more appreciably than changes in the structural nominal strains.