IN-PLANE DYNAMIC CHARACTERISTICS OF WOODEN DIAPHRAGMS (Part I)

Abstract

In-plane dynamic characteristics of wooden diaphragms were investigated using a full-scale and a model diaphragms. The full-scale diaphragm was a 11.18m-long by 6.38m-wide Swedish-type floor and the model diaphragm was a 2.40m-long by 1.20m-wide. Two tests among impact-hammer, exciting and shaking-table dynamic tests were alternatively performed for both diaphragms. The test data of both diaphragms showed that the natural frequency was proportional to the mode number and that the mode shapes were similar to sine-curves. Furthermore, the calculated natural frequencies based on the shearing vibration theory with the equivalent shear-stiffness obtained by the static loading test agreed with the natural frequencies due to the dynamic tests. It was suggested that the dynamic in-plane behavior of wooden diaphragms was consistent with the shearing vibration theory.