In the past study, we conducted compression tests with laminated veneer lumber of Japanese Larch. We observed the deflection and strain behaviour. As a result we could evaluate the bucking strength with Euler’s equation and Tetmajer’s method. For structural design we should expand the versatility of that method. Three wood species for structural members would be selected for these tests. Those were Japanese larch, Japanese cypress and Japanese cedar. For the test parameter, we set the 8types of slenderness ratio for the compression test and we conducted monotonic compression tests with pin-supported on both edges. For the mechanical properties we conducted compression tests with short column members and got yield compression for those materials. In the compression tests, we could see the bending deflection. We would get the ratio the maximum strength and yield strength for distinguish the limited slenderness ratio. As a result it was cleared that the limit slenderness ratio of these wood species was 100. And we could confirm that the Tetmajer’s method is useful for evaluation the yield strength.
A finite element model is developed to analyse, as a function of volume fraction, the effects of reinforcement geometry and arrangement within a timber beam. The model is directly validated against experimental equivalents and found to never be mismatched by more than 8% in respect to yield strength predictions. Yield strength increases linearly as a function of increasing reinforcement volume fraction, while the flexural modulus follows more closely a power law regression fit. Reinforcement geometry and location of reinforcement are found to impact both the flexural properties of timber-steel composite beams and the changes due to an increase in volume fraction.
This paper presents a research study about timber connections in moment resisting frames, with materials commercially available in Costa Rica. With new developments in engineered timber, the Costa Rican Seismic Code included a chapter on timber structures, defining moment resisting timber frames with several values of structural global ductility, depending on the local ductility of the connections. A research study was then carried out, with the objective of determining the structural behaviour and static ductility factor of a beam to column connection. Twelve specimens were constructed and tested, varying the geometric characteristics, wood species and type of bolts. The specimens consisted of a glulam beam and column segment connected with a different bolt pattern. The beam segment was loaded at its free end to induce a moment in the connection, and the ends of the column segment were simply supported. The rotation of the connection was measured by placing two LVDTs in the beam and two LVDTs in the column. It was found that the ductility factors achieved by the test specimens ranged from 2.0 to 2.7 in average. The moment capacity of the connections can be safely estimated using the nominal values of bending yield strength of the bolts and the dowel bearing stresses. These results are an important input for the Costa Rican Seismic Code and for the development of engineered timber in Costa Rica.
The research presented in this paper examines the performance of 3-ply and 5-ply Cross-laminated Timber (CLT) panels connected with Self-tapping Screws (STS). Different conventional joint types (surface spline with STS in shear and half-lap joints with STS in either shear or withdrawal) along with two innovative solutions were evaluated in a total of 198 quasi-static tests. The first novel assembly used STS with double inclination of fasteners in butt joints; the second was a combination of STS in withdrawal and shear in lap joints. The joint performance was evaluated in terms of capacity, stiffness, yield strength, and ductility. The results confirmed that joints with STS in shear exhibited high ductility but low stiffness, whereas joints with STS in withdrawal were found to be stiff but less ductile. Combining the shear and withdrawal action of STS led to high stiffness and high ductility.
