Evaluation of Mechanical Properties and Adjustment Factors of Wooden I-joists for Structural Design

摘要

The short-term and long-term loading tests were conducted on wooden I-joists manufactured with finger-jointed solid flanges and structural panel webs (Japanese plywood and Canadian OSB). We evaluated their bending, shear and partial bearing properties and adjustment factors of water absorption treatment, duration of load and bending creep according to the Japanese building code. Test results showed that the statistical characteristic values of maximum bending moment and bending stiffness of the I-joists satisfied the practical requirements and they could be satisfactorily substituted for solid joists of 2x10 dimension lumber. Comparison between web materials showed that the mechanical properties and long-term performance of the I-joists with plywood were less than those of I-joists with OSB. The I-joists with OSB, on the other hand, were remarkably degraded by water absorption treatment than the I-joists with plywood. These results are useful in appropriate structural design and reliable application of wooden I-joists.