Experimental analysis of crack propagation in stiffened box girders under variable-amplitude loading

Welded stiffened panels are integral components of large-scale structures such as naval vessels and bridges. Load fluctuations at various weld locations can cause crack initiation and propagation. These fatigue cracks could propagate up to a critical size leading to catastrophic structural failure. Although these structures are generally subjected to random variable-amplitude loading, most studies in literature have investigated crack propagation in stiffened panels under constant-amplitude loading. A comprehensive research program was launched in Oklahoma State University to investigate the fatigue crack growth (FCG) in stiffened structure under variable-amplitude marine loading. This program involved experimental analysis on middle-tension specimens tested under constant- and variable-amplitude loading. Additionally, an experimental fatigue test was conducted on a large-scale stiffened box girder specimen under variable-amplitude marine loading to validate crack propagation prediction approaches. This paper presents the details of the experimental investigation on both the small- and large-scale specimens and discusses the results. It presents detailed dimensions of test specimens, test protocols, load generation procedures, test observations, and crack growth profiles.