Evaluating the stress transfer and detailing of shape memory alloy transverse reinforced at the end region of prestressed concrete beams

Abstract

The end regions of prestressed concrete members are a small portion of the element, yet they are crucial for securing the serviceability and safety of the whole structural system. High prestressing forces and the eccentricity of strand locations during prestress transfer induce bursting and spalling stresses. These stresses result in cracking at the end region of concrete beams (i.e., entrant corners of dapped-end beams, girder web-flange zones, and girder web). This study investigates mitigating these cracks by using shape memory alloy bars as transverse reinforcement in the end regions of prestressed concrete beams, replacing conventional steel stirrups. An experimental study is performed to evaluate stress transfer by shape memory alloy’s shape memory effect to the concrete surface during shape memory alloy activation, and its numerical modeling technique is devised using finite element method. The effectiveness of stirrup is validated by finite element analysis in a large-scale girder designed based on the American Association of State Highway and Transportation Officials Load and Resistance Factor Design. Shape memory alloy bar detailing is also investigated experimentally and numerically to evaluate the feasibility of shape memory alloy transverse reinforcement. Experimental and numerical results demonstrate the effectiveness of shape memory alloy reinforcement in the end region of concrete beams.