This study aims to develop an improved understanding of the interfacial bond behavior of softwood glulam joints with bonded-in threaded steel rod. A total of 39 glulam joints with bonded-in single-threaded steel rods were tested to failure in the pull-pull configuration. The test results were presented in term of failure modes, load-relative movement response, pullout strength, and the corresponding slip. The distributions of bonded-in rod axial strain, interfacial bond stress, and relative movement were also analyzed to evaluate the local bond stress– relative movement response in the bond line. The results confirmed that the bond-relative movement response is dependent on the locations along the anchorage length, and the bond-relative movement responses located near both the loaded end and the anchorage end were observed to be stiffer than those at other locations. Finally, the predictions for the load capacity of the glulam joints with bonded-in threaded steel rod were carried out based on several existing empirical formulas.
This paper describes the test program of glued-in deformed bar timber joint conducted in pull-pull configuration, which aims to investigate the bond behavior of glued-in deformed bar systems in glulam. The varying parameter are bar slenderness ratio and glue-line thickness. In order to obtain the bond stress distribution along the anchorage length, special deformed bar with strain gauges attached internally were designed. Test results show that both the bar slenderness ratio and glue-line thickness have obvious influence on withdrawal strength and bond behavior of glued-in deformed bar joint. Failure modes of specimens are also analyzed in this paper. Ductile failure modes of glued-in rod timber joint could be realized with reasonable design.
Compression tests were conducted on the glulam members under different eccentricities, including three cases of 0mm,50mm and 100mm respectively, to study the mechanical performance of the new assemblage joints in reticulated timber shells. The bending stiffness and bending capacity of joints were evaluated, at the same time, the influence of failure mode and the changes...
This paper describes an experimental test program and theoretical analysis which examines the reinforcing in flexure of glued laminated timber (glulam) beams using fiber reinforced polymer (FRP) and steel materials. A series of four-point bending tests were conducted till failure on both unreinforced and reinforced Douglas fir glulam beams in a simply-supported scheme. The focus of this research was to evaluate the effects of reinforcing materials, reinforcement ratio and arrangement on the flexural behavior. Test results showed that the flexural capacity, flexural global stiffness and timber tensile strain at failure were all improved considerably for reinforced timber beams when compared to the unreinforced control beams, in which the average improvement reached 56.3%, 27.5% and 49.4%, respectively. On the bases of the experimental results, a theoretical model was proposed to predict the flexural capacity and flexural stiffness of the reinforced timber beams. Most of the differences between theoretical and experimental results for both flexural capacity and flexural stiffness were within 10.0%, which showed a high accuracy of the proposed model. Subsequently a parametric analysis, which includes the axial stiffness ratio of reinforcement to timber, the relative location of tensile reinforcement, and the strength ratio of reinforced timber between flexural tension and compression, was undertaken to investigate the effects of the influential factors for both flexural capacity and flexural stiffness.
Glued-in rod is a type of effective connector for timber structures. In the last decades, considerable researches have been conducted on the bond behavior between timber and glued-in rod experimentally and theoretically. This paper presents the numerical simulation on the bond behavior of glulam joints with glued-in steel rod. Glulam is modelled as the orthotropic elasto-plastic material. Adhesive and steel rods are modelled as isotropic materials. Non-linear spring element was employed to simulate the local bond stress-slip relations at different locations along the bonded length. The numerical results indicate that non-linear spring element can be used to simulate the bond behavior of the glued-in steel rod glulam joints effectively. Moreover, The numerical results obtained by considering the local bond relations at different locations is in a better agreement with the experimental results than that obtained based on the bond stress-slip relation at loaded end.
This paper describes an experimental test program and theoretical analysis which examines the reinforcing in flexure of glued laminated timber (glulam) beams using bonded-in carbon fiber reinforced polymer (CFRP) bars. A series of four-point bending tests were conducted till failure on unreinforced, passively reinforced and prestressed Douglas fir glulam beams in a simply-supported scheme. The focus of this research was to evaluate the reinforcing efficiency of both passively reinforced and prestressed beams. Test results showed that the flexural capacity of the reinforced, prestressed, prestressed & reinforced (bottom prestressed and top reinforced) beams greatly increased by 64.8%, 93.3% and 131%, respectively. While the maximum improvement of the bending stiffness reached 42.0%. Another important finding was that the extreme fiber tensile strain of timber beams at failure could be remarkably increased due to the presence of the tension reinforcement, which indicated it overcomes the effects of local defects and therefore the failure mode was changed from brittle tension failure to ductile compression failure. Based on the experimental results, a theoretical model was proposed to predict the flexural capacity of unreinforced, reinforced and prestressed timber beams, which was validated by the test data.