Serviceability-based deflection of RC beams with stainless steel reinforcement: A revised design approach and reliability assessment

Abstract

This study addresses a critical gap in current design standards by proposing a tailored deflection prediction model for stainless steel RC beams, accounting for their unique nonlinear and strain-hardening behavior. Stainless steel RC beams tend to exhibit larger deflections under comparable loading conditions than their carbon steel counterparts, owing mainly to the lower bond strength and nonlinear stress-strain response. Since the serviceability limit state often governs the design of RC members, there is a critical need for simplified and accurate deflection prediction methods specifically tailored for stainless steel reinforcement. Current global design codes lack explicit provisions for stainless steel RC members, typically neglecting the unique nonlinear and strain-hardening behavior of stainless steel. To address this limitation, the present study compiles an extensive experimental database of 150 stainless steel RC beam specimens from the literature and evaluates the deflection predictions of established design codes, including ACI 318-19 and Eurocode 2. Building upon this analysis, a modified design approach is proposed. A reliability analysis demonstrates the enhanced accuracy and robustness of the proposed method, offering a more dependable tool for deflection estimation in stainless steel RC beams under service loads. The results show that the mean predicted-to-experimental deflection ratios at 30 % of ultimate moment were 0.98 (EC2), 0.77 (ACI), and 0.99 (proposed). Whereas at 67 %, both EC2 and the proposed method achieved 0.88, outperforming ACI at 0.75. The proposed model improves prediction accuracy under service conditions and provides a more reliable tool for future stainless steel RC beam design.