Static and Fatigue Strengths of Beams Containing Prestressed Concrete Tension Elements.

摘要

The study concerns the static and fatigue behavior of composite beams containing 2in. square precast tension element,concentrically prestressed with a single 7/16in. diameter 7-wire strand. The element was positioned in the beam of 6in. wide, 9in. deep and 120in. long,such that its controid was 2in. from the tension face. Two static tests were conducted to obtain the elastic and inelastic load-deflection behavior of the composite member and to determine the load Pcr corresponding to initial cracking in the tension element,and Pu the ultimate load. Repeated load tests were conducted on seventeen beams. The principal objective was to determine the behavior of the tension element under conditions that simulated those at a continuity connection in a highway bridge;and in particular to ascertain the fatigue strength of the tension element. The scope of this investigation was limited to the application of repeated loads over a range of 0.5 Pcr to 2 Pcr. Test results clearly indicate that the magnitude of the peak load determines the mode of failure. Results revealed that use of the tension element for continuity connection creates a section that is superior to one using conventional reinforcement,as it increases the cracking load of the section by 52% and thus provides better protection of the reinforcement against corrosion. (Author)