DESIGN OF WOOD DIAPHRAGMS WITH OPENINGS

The existence of openings in diaphragms causes concentration of shear forces around the openings and the generation of axial forces in the f raming. In 1981, the Applied Technology Council developed the only gui delines for designing diaphragms with openings. The procedure for dete rmining the shear around the opening, however, is complicated and has not been experimentally verified. Accordingly, simplified equations fo r determining the shear forces in diaphragms with openings are derived in this paper. The application of the membrane-to-brace replacement m ethod to diaphragms is also discussed. Horizontal loading tests are co nducted on three floor diaphragms designed to the same load. The ultim ate loads are almost the same, regardless of the existence of the open ing. The observed unit sheer around the opening is close to the calcul ated value. The observed deflection is smaller than the value calculat ed on the basis of the nominal stiffness for the materials and the fas teners by 14-28%. It can be said from these results that all the metho ds perform well as a practical design tool.