Experimental evaluation of certain repair techniques for cracked structural steel components

This paper investigates the appropriateness and effectiveness of certain repair techniques for cracked structural steel components. Generally, there exist two options for dealing with cracked steel components; either replacement or repair. This paper focuses on the cases where replacing the cracked component(s) is not feasible at the time of crack(s) discovery, however, replacement will take place in the future. Thus, the repaired component will serve in the structure for a specified time depending on the inspection. Also, the level of inspection after repair is assumed to be adequate. The main goal of the investigation is to address the problem of retaining the original load carrying capacity of the component in both yield and ultimate loads with adequate ductility. Seven different repair techniques with two main repair technique categories have been considered; direct welding of the crack faces using Gas Metal Arc Welding (GMAW) or splicing the wake of the crack either by welding or bolting. Two specimens of each technique have been tested. For the first category, different blunting hole diameter (5, 10 and 15 mm), and different preparation of crack faces prior to welding (grooved vs. non-grooved) have been considered. Results have shown that most of the repair techniques have succeeded in retaining the initial yield load of the component, however, only three techniques have shown similar ultimate load to the virgin specimen. The most successful technique using direct welding of the crack faces is to groove the crack faces and to blunt the crack tip with a hole diameter of 10 mm or less. Larger hole diameter would increase the yield load capacity with a considerable reduction in both ultimate load and ductility. On the other hand, the direct application of welding to the crack faces without either blunting or grooving the crack faces has shown the worst results. Splicing the crack wake through welded splices using GMAW is efficient in retaining both the load carrying capacity and the ductility of the virgin specimen provided that the weld thickness should be designed such that the failure occurs outside the splice zone. © Faculty of Engineering, Alexandria University.