Parametric Study of Factors Impacting End Zone Cracking of Pretensioned Concrete Bulb-Tee Girders

Presented By: Thomas Carnes, Virginia Polytechnic Institute & State University Description: In pretensioned concrete bulb-tee girders (PCBTs), cracking in the end zones often occurs during strand detensioning, posing a durability concern. This study investigated factors contributing to end zone cracking in PCBTs utilizing nonlinear finite element analysis. First, numerous configurations of 69 in. (1753 mm) deep PCBT end zones were analyzed. These configurations included a variety of prestressing strand quantities, prestressing strand configurations, reinforcement configurations, reinforcement sizes, web widths, concrete material properties, and girder lifting locations. Finally, the extension of the most optimal configurations into PCBTs of other depths varying from 29 in. (737 mm) to 93 in. (2362 mm) was investigated. This study revealed that certain configurations, such as those including splayed draping and strand debonding, performed better than the baseline configuration and even configurations with more than twice as much reinforcement.