Modeling Damage and Failure in Pretensioned Concrete Girders Fabricated with Large-Diameter Strands

Abstract

Pretensioned concrete elements are commonly fabricated with strands 12.7 or 15.2 mm (0.5 or 0.6 in.) in diameter; however, the industry has seen interest in using larger-diameter strands in recent years. The use of larger-diameter strands results in greater transverse tensile stresses within the girder end regions, which may increase cracking at the time of prestress transfer. Such cracks may continue to grow during service and cause durability concerns. Moreover, increased damage around the strands and at the web–flange interfaces may lead to unconventional failure mechanisms, such as anchorage-induced or horizontal shear failures. This paper introduces a modeling approach for investigating the performance of pretensioned girders fabricated with strands 17.8 mm (0.7 in.) in diameter from prestress transfer until failure under shear-critical loading. Data from seven full-scale prestress transfer tests and 10 load tests showed that the model can capture the transfer lengths, end-region stresses, and cracking at prestress transfer as well as load-deflection response and failure modes. Subsequently, three remedial end-region reinforcement details were investigated using the validated approach to examine their efficacy in controlling end-region cracks and stresses.