Flexural capacity and fatigue performance of full-scale FRP-concrete composite vehicular bridge girders

Since 2020, hybrid fiber reinforced polymer composite tub (CT) girders have been used in the construction four in-service vehicular bridges in the United States and two additional bridges are under construction. ever, despite their growing acceptance, there are very few FRP highway girder bridges throughout the only one full-scale destructive test of a CT girder has been conducted to-date, and girder fatigue life has explored. To provide additional strength data, a full-scale CT girder was manufactured and tested to flexure. The results of this test confirmed the CT girder's design efficiency, performance of its novel girder shear connectors, and expected capacity determined through nonlinear moment-curvature analysis that for the nonlinear compressive response and cracking of the concrete deck. A second identical CT girder was subjected to 3000,000 cycles of factored fatigue load and subsequently tested to failure in flexure to a direct assessment of cumulative fatigue damage. Full-scale fatigue tests of complex, vacuum-infused, glass-carbon members are unusual, making this test particularly valuable. The girder did exhibit accumulation during the first 1500,000 cycles as evidenced by increasing deflection for the same applied but deflections remained relatively constant for the remaining cycles. The failure test of this specimen revealed 33 % loss in flexural strength due to flexural fatigue damage. However, the post-fatigue flexural strength exceeded AASHTO capacity requirements by 43 %, indicating a significant post-fatigue safety margin. subsequent examination of girder fatigue life accounting for damage accumulation under realistic truck spectra indicates that in many applications, CT girder bridges have estimated fatigue lives in excess of 100 although caution must be exercised with when interpreting this result given that only one specimen was under specific laboratory conditions.