Experimental investigations of flexural and shear behavior of continuous prestressed HSC beams under repeated loads

Abstract

The results of an experimental study into the flexural and shear conduct of continuous two span unbonded posttensioned high strength concrete beams subjected to static and a limited number of repeated loading cycles are presented in this paper. The experimental program comprising testing and experimentation of four continuous unbonded posttensioned high strength beams with a total length (4300) mm. The main objective of this study was to see how the strength and serviceability of continuous prestressed concrete beams were affected by restricted repeated loading cycles. As a result, these beams were split into two similar groups. The first set consisted of two beams to study the flexural behavior. The second set consisted of two beams to study the shear behavior. For each set one tested under static loads and the second tested under repeated loads. They were subjected to two concentrated loads in the middle of each span loads up to destruction. It was determined that the repeated load ranged between 0.4 and 0.6 of the ultimate load generated by the static test. Immediately following the ten cycles, the load was withdrawn, and the beams were subjected to a monotonic static test until failure was achieved. Recorded the cracking and ultimate load capacity, midspan deflections, and crack widths. The experimental results explained that the ultimate flexural and shear strength for beams that are tested under repeated loads is a little reduced (1.7%) and (3.9%) comparing with the strength of the identical beams under monotonic static loading and increasing the ultimate deflection after ten cycles of repeated loading, decreased about (5.3%) and (15.1%) for flexural set and shear set, respectively.