Design of CFRP-strengthened stainless steel tubular sections subjected to web crippling

This paper presents a nonlinear finite element analysis and also depicts the design of stainless steel hollow square and rectangular sections strengthened by CFRP under web crippling loading configurations. Current design rules do not provide sufficient information for predicting the performance of CFRP-strengthened stainless steel hollow sections against web crippling. To develop a new comprehensive design rule, this research provided a nonlinear finite element analysis (FEA) based on a series of laboratory tests. The tests were conducted subjected to four different loading conditions, end-two-flange (ETF), end-one-flange (EOF) interior-two-flange (ITF) and interior-one-flange (IOF). Geometric and material nonlinear finite-element models were developed, substantiated by the experimental results. The traction separation law was used to simulate the debonding mechanism between the CFRP plate and stainless steel tubes in the nonlinear analysis process for the cohesive zone modeling. The finite-element models explicated well the behavior of CFRP strengthening and closely predicted the ultimate load-carrying capacity, web-crippling failure modes, as well as web-deformation curves of the tested sections. A parametric investigation was conducted using the verified finite element models for tubular sections with different dimensions. For CFRP enhancement of stainless steel members, the validated finite element models has been demonstrated as an constructive and time-saving method to determine the strengths of web crippling. The proposed design equation predictions also agreed well with the tests and numerical results. The web crippling strengths can be predicted effectively by the proposed design equation for CFRP enrichment stainless steel hollow sections against web crippling loading configurations.