Comparison of Fatigue Performance between Welded Joint Containing Undercut and Grinded Surface

Abstract

The load of heavy trucks passing over the bridge causes fluctuation stresses in all cross sections of the structural elements of the bridge. As a result of this dynamic load, the steel bridge can experience failure long before reaching the allowable stress of the conventional design approach, this phenomena is called fatigue failure. Fatigue failure is more susceptible to connection parts of bridge elements, such as welded joints. The aim of this research is to obtain fatigue performance from welded joints of SM570 steel plate material due to dynamic loads with two different conditions. The first condition is the test object without removing undercut defects, and the other condition is grinded completely by removing undercuts. This research was carried out by giving stress range at 110 MPa or threshold condition and higher stress range of 250 MPa on the welded joint test specimen. The test results are then plotted on the detailed B of AASHTO 2012 Fatigue SN-curve. The results of fatigue testing shown that by giving a stress range of 110 MPa on the test specimen comply with the fatigue standard according to detailed B-AASHTO 2012 Fatigue SN-curve. The test results by 250 MPa stress range testing, both types of specimens shown very different fatigue performance, SM570 steel welded joints with grinded surface shown a much higher fatigue performance compared to joints containing undercuts.