Response of continuous CFRP prestressed concrete bridges under static and repeated loadings

A detailed experimental investigation of a developed continuous double-T (DT) bridge system, internally and externally prestressed with carbon fiber reinforced polymer (CFRP) tendons, was conducted under static, repeated, and ultimate loads. The bridge model was subjected to 15 million cycles of two repeated loads of constant amplitudes equivalent to the service load at Midspan I and twice the service load at Midspan 2. The effect of repeated loads on various parameters was examined before and after the post-tensioning adjustment (increase in the post-tensioning forces after 7.5 million cycles of repeated loads). It is observed that the effect of repeated loads on the forces in post-tensioned externally draped tendons is negligible. However, the effect of repeated loads on other parameters such as deflection and strain depends on the magnitude of repeated loads and becomes more significant under loads greater than the service load. Also, the presence of continuous externally draped CFRP tendons (in the positive and negative moment regions), along with CFRP grids, results in a ductile CFRP continuous bridge system.