STRUCTURAL PERFORMANCE OF COMPOSITE BOX BEAMS WITH CORRODED BOTTOM FLANGE UNDER MONOTONIC AND REPEATED LOADS

The current research is dedicated to studying the flexural behavior of composite box beams with corroded bottom flanges. Six simply supported beam specimens were manufactured and tested. The composite box beams were fabricated with steel box beams of 1100mm, 100mm, and 100mm for length, width, and height, respectively, while the concrete deck slabs were made with dimensions of 1100mm, 400mm, and 50mm for length, width, and thickness, respectively. The composite sections were formed by connecting the RC deck slabs with the steel box beams by using a headed shear connector. Three main variables were considered; the load type (monotonic or repeated), bottom flange thickness (with or without corrosion), and whether to consider or ignore the strengthening by CFRP strip. Experimental results indicated that the ultimate loads were decreased by 29-33% for the corroded bottom flange beam specimens; while the ultimate loads for the strengthened beam specimens were increased by 60-67% as compared with the un-strengthened corroded corresponding beam specimens. Also, the change of the applied loads from monotonic to repeated leads to a reduction of the ultimate load by 17-22%.