Stress Intensity Factors for Cracked Steel Girders Strengthened with CFRP Sheets

Abstract

This paper presents the fracture characteristics of cracked wide-flange steel girders (W18–W40, W460–W1000 in metric) strengthened with carbon fiber-reinforced polymer (CFRP) sheets. A broad range of parameters are considered to study their effects on the crack-tip stress intensity of the girders: flange-to-web area ratios, crack depth-to-height ratios, CFRP-to-steel area ratios, CFRP-to-steel modular ratios, and CFRP-bond widths. A three-dimensional finite-element approach is proposed and validated with a previously conducted experimental program. A total of 1,240 models, i.e., 40 unstrengthened and 1,200 strengthened girders, are used to evaluate the crack-tip behavior of the W-shape girders. The response surface-regression analysis procedures (RSREGs) are used to develop correction factors for the stress intensity of the girders. Stochastic simulations are conducted to probabilistically understand the vulnerability of the cracked girders and evaluate the efficacy of CFRP strengthening in terms of reducing stress intensity.