Prediction of Fatigue Life of Welded Beam-to-Column Connections under Earthquake Loading

Abstract

A building may suffer damage during an earthquake as a result of inelastic deformations developed in the members or connections. It is important that the structural integrity of the building be assessed to ensure the safety of the occupants. This assessment includes evaluating the ability of the structure to resist the demand from subsequent aftershocks and a major earthquake. In this paper a practical methodology to determine the low-cycle fatigue life of welded structural steel connections subject to inelastic cyclic loading is presented. The methodology is based on concepts of low-cycle fatigue and micromechanics, where an accumulated crack length based on a time history of strain and the corresponding triaxiality stress condition that develops in the structural component is calculated and used to establish the fatigue life. The methodology was used to predict the fatigue life of welded beam-to-column connection test specimens subjected to inelastic loading. A comparison with test results indicates that the methodology predicts reasonably well the relationship between number of cycles to fracture and the plastic rotation range observed in the test specimens.