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UBC Theses and Dissertations

Experimental investigations of residual and fatigue capacities of timber connections with glued-in FRP rods Zhu, Hong


Well-designed and executed glued-in rod connections can provide excellent structural performance in terms of strength, stiffness, and efficiency in load transfer. The pull-out residual and fatigue capacity of timber connections with glued-in Glass Fibre Reinforced Polymer (GFRP) rods bonded by Polyurethane adhesive (PUR) have been studied extensively. Previous research conducted at the University of British Columbia in Vancouver (UBC) investigated the impact of anchorage length and rod diameter on the performance of glued-in GFRP rods glulam joints. Each of the test specimens consisted of two glued-in rod connections, with one rod inserted in each end-grain face. One side joint failed brittle but the other side joint survived under quasi static tensile test. The first rod connection to fail could be called the broken side or first side and the unbroken rod could be called the surviving side or second side. However, universal agreement on the design of glued-in rod connections has not yet been reached.The experimental work for this thesis was performed in the Timber and Material Laboratories at UBC. In the pull-out tension test, which is a follow-up test to previous study regarding the geometric characters of the glued-in GFRP rods joints, the short term tensile capacities of the surviving sides of symmetrical glued-in rod test specimens were determined. A total of 25 test series were tested with 5 replicates each where the anchorage length and the rod diameter were the same. The surviving side capacities were not always higher than the first sides, possibly explained by damage caused through the previous quasi static tensile tests. Subsequently, the average capacities from each series based two sides data were compared to the calculated predictions from different design approaches and it was shown that the German Design Code could best predict the capacity of symmetrical glued-in-rod connections.The fatigue tests were conducted based on the novel “PYHBAL” loading protocol which involves two single step tests and one load increase test. Compared to conventional fatigue tests, the “PHYBAL” method can provide fast and economic fatigue estimation. The fatigue capacity of the glued-in GFRP rod joints was approximately 65% of short-term capacity.

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