Flexural Fatigue of Glulam Beams with Fiber-Reinforced Polymer Tension Reinforcing
Publication Name: Proceedings of the ASCE Structures Congress 2004
Publication URL: https://ascelibrary.org/doi/10.1061/40700%282004%2948
Recent research into improving glued laminated (glulam) beam performance has focused on the use of fiber-reinforced polymer (FRP) reinforcement bonded to the glulam tension face to increase flexural capacity. However, to date the fatigue resistance of FRP-reinforced glulams has not been quantified. This is a serious concern given that such beams are increasingly used as bridge girders, which see large numbers of load cycles during their design life. In this study, nine Douglas fir glulam beams with 1.9% by volume FRP tension reinforcing are tested in load-controlled flexural fatigue and their residual strengths are then determined from static bending tests. Three of the specimens had reinforcing running the full length of the tension face, and the remaining six specimens had partial-length reinforcing to study the effect of this important detail. The loadings and number of fatigue cycles used in the testing program are consistent with accepted bridge design practices. The results of the tests indicate that girders with full-length or properly confined partial-length reinforcing have sufficient fatigue resistance for use as bridge girders. However, beams with unconfined partial-length reinforcing exhibited markedly poorer performance, and may not be suitable for use when fatigue is a design consideration.