Flexural behavior of side-by-side box-beam bridges: A comparative study

Abstract

This article compares box-beam bridge models reinforced and prestressed with different types of reinforcement. The first box-beam bridge model was reinforced with prestressed carbon-fiber-composite cable (CFCC); the second box-beam bridge model was reinforced with conventional prestressed steel strands. The bridge models were identical in cross-sectional dimensions and were constructed by placing four box beams adjacent to one another and connected by means of transverse post-tensioning (TPT) forces at transverse diaphragms, shear keys, and deck slabs. The paper shows how load-distribution and strain-distribution tests were conducted on both bridge models in both their uncracked and cracked stages. In addition, both bridge models were subjected to an ultimate load test to study the overall flexural response. The results presented in the article show that the bridge models exhibited similar behavior during the strain- and load-distribution tests. As expected, the CFCC bridge model experienced a flexural compressive failure due to crushing of deck-slab concrete in the compressive zone, whereas the conventional bridge model experienced a flexural ductile failure due to yielding of steel strands. However, the CFCC bridge model exhibited a higher ultimate strength but a lower energy ratio compared with the conventional bridge model. In addition, the unbonded TPT strands of both bridge models remained intact, even after ultimate failure, and experienced a similar variation in TPT force during the ultimate load test. The results obtained from the strain distribution, load distribution, ultimate loads, modes of failure, deflection, strains, and energy ratios of CFCC and conventional bridge models are presented.