Studies on the Structural Performance of Wood Based Wall Panels

Abstract

Tests were carried out to examine the influence of the construction variables on the structural performance of load-bearing wall panels used in prefabricated wooden houses.
Six types of framings were constructed of spruce wood (Fig. 1), and the framing members were cut out for each section, 4.5 by 7cm, except for the bottom members, which were each 7 by 7cm (Fig. 2). The skin materials of 6mm lauan plywood were jointed on both sides or on one side of the framing according to the type of the specimens.
In Figs. 4, 5 and 8 the schemata of loading specimens are shown respectively. The bending tests were carried on over the span of 220cm with the load applied at each quarter point. The racking tests were performed without installation of the tie rods as of ASTM standard. The loading was repeated with increased load till a certain specific stage was reached and still continued evenly to the failure of the material (Fig. 7). The compression tests were performed of the specimens, except specimens SR₁, with the load applied on their center line of thickness of the specimens, using the knife edges on both their ends as equipment. The specimens SR₁ were tested in accordance with ASTM standard. The results of these tests are summarized as follows:
In the bending tests the ratio of the observed flexural rigidity to what was calculated is various with the arrangement of framing members, the method of plywood-timber joints and the form of stressed skin construction (Tables I, III and IV). This fact shows that the effective breadth of the skin has considerable effect on the flexural resistance of the panel.
In the racking tests on glued and nail-glued specimens without opening it is shown that the racking load is little affected by the difference in the framing construction, so long as the deformation at the upper end is horizontally equal to 1/100 of the height of panel (P_1/100kg/m)(Table II). The racking resistance of nailed specimens is weaker than that of glued specimens (Tables II, III and Fig. 7).
In the racking tests of specimens with opening the position of the opening makes larger difference to the racking resistance than the opening ratio does (Table III and Fig. 3). The glued specimens (SRC, ERD, SRG) being equipped with powerful plywood skin and reinforced frame around the opening, show but little decrease in the racking resistance.
In the compression tests it is shown that the buckling load increases so far as there is increase in the vertical members of framing. The value of the buckling load calculated by Euler's formula for the pin end column, substituting the observed flexural rigidity, is in good agreement with what was observed, though with a few exceptions (Table IV).