Flexural Behavior of a Carbon Fiber–Reinforced Polymer Prestressed Decked Bulb T-Beam Bridge System

Abstract

Experimental and numerical investigations were conducted to evaluate the performance of a newly developed bridge system. Through the investigation, a decked bulb T-beam bridge model was constructed, instrumented, and tested under service and ultimate loads. The bridge model had a width of 2.59 m (8.5 ft), an effective span of 9.45 m (31 ft), a depth of 356 mm (14 in.), and was composed of five adjacent decked bulb T-beams. The T-beams were interconnected at their top flanges using 76-mm (3-in.)-wide ultra-high-performance concrete (UHPC) shear key joints and five full-depth equally spaced transverse diaphragms along the span. Each diaphragm was posttensioned with two nonbonded transverse carbon fiber composite cable (CFCC) strands. The investigation revealed that the developed decked bulb T-beam bridge system maintained its structural integrity under service loads with signs of distress in neither the shear key joints nor top flanges. UHPC shear keys with the transverse diaphragms were adequate to achieve monolithic action across the width of the bridge model. In addition, transverse posttensioning forces were effective in restoring the structural integrity of the bridge model when cracks were artificially induced in the shear key joints. At the ultimate limit state the bridge model exhibited compression failure by crushing of the concrete in the top flange. The compression failure was associated with low ductility, a dense cracking pattern, and excessive deflection.