CRACKING IN LONG-SPAN PRESTRESSED CONCRETE AASHTO GIRGERS DURING PRODUCTION

摘要

During the production of long-span AASHTO girders, full-depth vertical cracks have been observed within the mid-third of the girder before the prestressing strands are detensioned. The cracks run across the top flange transversely and extend downward through the web, reaching into the bottom flange of the girder. With the increasing use of high-performance concrete, more and more longer-span girders are used by bridge engineers. These girders would be more vulnerable to the cracking problem during their production. This paper presents the results of an investigation to determine the cause(s) of the cracking problem. It was found that the cracks developed due to restrained thermal contraction of the girders as well as the tendons during the cooling period following the overnight steam or heat curing. Recommended acceptance criteria for such cracked girders are discussed.