Fatigue of glulam beams with fiber-reinforced polymer tension reinforcing
Publication Name: Forest products journal
Publication URL: https://agris.fao.org/agris-search/search.do?recordID=US201300992608
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 percent E-glass epoxy FRP tension reinforcing were tested in load-controlled flexural fatigue and their residual strengths were 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 were consistent with accepted highway 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 highway 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.