Finite Element Analysis of Diaphragm Systems

摘要

This report describes a mathematical model for the partially composite diaphragm system, which might be a wood stud wall or a wood joint, using the finite element method. A review of research related to wood stud wall systems and wood joist floor systems emphasizes the need for a more flexible, rational method of structural analysis for the complex wood diaphragm system. Reasons for adopting the finite element method and assumptions of the analysis are detailed. Three types of elements were used to implement the model; the sheathing, the beam, and the sheathing - beam connection. The disussion of the model's computational aspects covers large - scale system solution schemes, the Gauss elimination scheme, blocking techniques, nonlinear behavior of connection element, and second - order analysis for axial force effect. The report also covers verification of the analytical model which used a FORTRAN language program and then compared the output with published experimental results and another analytical model, Nonlinear Analysis of Floors (NONFLO). The study concluded that sufficient accuracy may be obtained in comparing computer results for wood joist floors with experimental results from full - scale floor tests. In addition, using the concept of connector element can simulate the partial composite action in the diaphragm system with good consistency. The model tended to underestimate the floor system with gaps, probably because it neglected the stiffness of these gaps. The model appears to simulate the second - order effects in a reasonable manner, assuming the wall is loaded only in - plane forces. Drawings, formulas, graphs, and references are provided. The appendix describes the scheme in assembling and solving the structural system of equations.