FLEXURAL PROPERTIES OF GLULAM PARALLEL-CH ORD TRUSSES WHOSE NORDAL POINTS ARE COMPOSED OF SHEAR-PLATE CONNECTORS AND WHOSE DIAGONAL JOINTS ARE COMPOSED OF DRIFT-PINS

A glulam parallel-chord truss (denoted as a truss girder) whose nodal points were composed of shear-plate connectors and whose diagonal join ts were composed of drift-pins with steel insert plates was investigat ed. For calculating the mid-span deflection delta0, an apparent shear rigidity, GAMMA(W), of the truss girder was derived by considering the slip deformation of drift-pins, shear-plate connectors, and the elast ic deformation of the diagonal members as the shear deformation of a u nit panel in the truss girder. The mid-span deflection of the truss gi rder, delta0, was calculated as a sum of the bending deflection delta( b) and the shear deflection delta(S). Three types of test specimens of 9 m span lengths were fabricated using Larch (Larix sp.) glulam membe rs, and tested by the pulley-wire loading system, intending a uniforml y distributed load. However, the actual load distribution was thought to be lineally inclined due to the effect of friction between the wire and the pulley because the ratio of reaction forces at the Supports A and B (k V(B)/V(A)) was not 1 but about 1.8. Comparisons between the observed total load (P(t)) -deflection (delta0) relationship and the c alculated ones showed that the initial slackness due to the clearance between shear-plate hall and pre-drill hole in the steel plates was on e of the major cause for the discrepancy between the prediction and th e observation. The use of P-DELTA data of the fasteners taken from the un-destroyed parts of specimens subjected to 3 or 4 times cyclic load s was another cause for the discrepancy between the prediction and the observation.