Challenges Of ACI 318-19 Revisions To Flexural Design Of RC Beams Considering Higher-strength Reinforcements

Abstract

For flexural design, the 2019 Building Code of the American Concrete Institute (ACI 318-19) revisions allows the use of high-strength reinforcements and concretes as well as new reinforcement strain limits for reinforced concrete (RC) structures. As a result, more economic flexural design of RC members with lower amount of longitudinal steel reinforcements or smaller sections will be appreciated. However, such benefits may probably introduce another issue of deflection analysis and depth (thickness)-span limitations in the coded serviceability requirements. From the viewpoint of mathematical programming, this topic is of constrained optimization problems with multiple decision variables and object functions. To address this issue, an Excel-spreadsheet modeling to integrate the flexural reinforcement design with the coded serviceability requirements of RC beams was developed, in which the Generalized Reduced Gradient (GRG) based nonlinear optimization method defaulted in the Excel-Solver is applied to search feasible (or optimal) longitudinal reinforcements for RC beam design. The results indicates that the serviceability requirements should be assessed in flexural design of slender RC beams if higher-strength reinforcement is taken into account.

Keywords

• aci 318-19
• beam
• deflection
• design
• rc
• serviceability
• usd