An experimental investigation was carried out at the Construction Technology Laboratories of the Portland Cement Association to determine the effect of repetitive loading on the behavior and strength of girders with blanketed strands. Six full-sized Type II AASHTOPCI girders, each 50 ft (15.24 m) long, were tested. Two girders contained draped strands. The other four had straight strands with four tendons blanketed at each end. Strands were 7/16-in. (11.1 mm) diameter, Grade 250, stress relieved, and had a brown surface rust. Controlled variables in the test program were load level, development length, and use of ties to confine the concrete in the stress transfer region of the blanketed strands. All specimens were cracked prior to fatigue loading. The test program called for 5 million cycles of loading between dead load and dead load plus live load. Static tests to full dead load plus live load were performed before cyclic loading and after 1, 21/2 and 5 million cycles. At the completion of 5 million cycles, the girders were tested to destruction under static load. This paper summarizes the experimental investigation' and presents the results of the tests.
