| The introduction of mass-produced glass fiber reinforced plastic (GFRP) structural shapes in bridges and other construction dictates the need to understand the fatigue behavior of these shapes. This study describes the fatigue performance of GFRP pultruded I-beams; an experimental study was conducted on both polyester and vinyl ester I-beams, under cyclic patch loads to monitor the fatigue performance, failure pattern, and stiffness degradation that could happen during the course of fatigue loading. The stress-range versus number of cycles, S-N curves, were produced for both polyester and vinyl ester beams considering the obtained mode of failure which was due to local crushing of the web matrix in the transverse direction under the applied patch load. An experimental study and finite element analysis were carried out to investigate the strength of these beams under the monotonically applied patch load because the obtained failure mode was the same like that under the cyclic load. Some equations were proposed to calculate the strength of pultruded beams under patch load and the minimum width of patch load required to avoid this local mode of failure. |
