Refined Analysis of Fatigue Crack Initiation Life of Beam-to-Column Welded Connections of Steel Frame under Strong Earthquake

Abstract

This paper presents a refined analysis for evaluating low-cycle fatigue crack initiation life of welded beam-to-column connections of steel frame structures under strong earthquake excitation. To consider different length scales between typical beam and column components as well as a few crucial beam-to-column welded connections, a multiscale finite element (FE) model having three different length scales is formulated. The model can accurately analyze the inelastic seismic response of a steel frame and then obtain in detail elastoplastic stress and strain field near the welded zone of the connections. It is found that the welded zone is subjected to multiaxial nonproportional loading during strong ground motion and the elastoplastic stress-strain field of the welded zone is three-dimensional. Then, using the correlation of the Fatemi-Socie (FS) parameter versus fatigue life obtained by the experimental crack initiation fatigue data of the structural steel weldment subjected to multiaxial loading, the refined evaluation approach of fatigue crack initiation life is developed based on the equivalent plastic strain at fatigue critical position of beam end seams of crucial welded connections when the steel frame is subjected to the strong earthquake excitation.

Fatigue Properties Estimation and Life Prediction for Steels under Axial, Torsional, and In‐Phase Loading

“…For the life prediction under axial, torsional, and multiaxial in-phase loading, the von Mises equivalent strain parameters combined with the Manson-Coffin equation can obtain good prediction results, which were verified by a large amount of fatigue test data [18,19]. e equivalent strain model used for the fatigue life prediction in this investigation is given as…”

Effect of Welding Residual Stress on Along-Wind Fatigue Life of Welded Joints in Guyed Mast

“…Since the mechanism of fatigue damage caused by crack initiation for structural steel obey the metal crystal slip rule, it can be considered that the fatigue damage occurs on the maximum shear stress plane, which can be defined as the critical plane according to the multiaxial fatigue theory, at the fatigue danger point of the key welded joints [19,20]. If the stress state of the fatigue danger point is proportional, the angle of the critical plane is constant, while if the stress state is nonproportional, the angle time history of the critical plane varies [15,21].…”

Investigation of Behavior of Interior Steel Connections With Openings in Beam Web and Flange Under Monotonic Loading

“…Many studies have investigated the behavior of connections [35][36][37][38][39]; also, the behavior of prefabricated beam-to-column connections were studied by many researchers [40][41][42] among which [40] utilized short post-tensioned prestressed strands to prevent on-site aerial tensions. Furthermore, the connection of H-Shaped steel beam to box columns with flange plate connection was scrutinized by [43].…”