The goal of this thesis is to determine whether continuity ties in large wood diaphragms are stiff enough to engage and provide diaphragm flexural stiffness in a collective chord model. Four series of continuity tie assemblies using Simpson Strong-Tie steel connectors were tested to determine the stiffness of each assembly. The results found from testing were applied to an example building and then analyzed using both the traditional chord method and the collective chord method. The completed analysis on a typical size warehouse building showed that the collective chord model will act inadvertently on an existing building designed with a traditional chord, or alternatively will potentially act intentionally in the design of a new building. The relative stiffness of the continuity ties will determine if they engage and allow them to act collectively. The testing and analysis completed creates a basis for further research into the actual static and dynamic behavior of these diaphragms. The collective chord model does seem to be a reasonable approximation for how diaphragms actually behave. If more research is conducted into different shaped and sized buildings to confirm that the collective chord model will work on most buildings then it will be a more accurate way to design new diaphragms and analyze existing diaphragms than the current traditional model.

Analytical models of wood-frame shear walls and diaphragms for use in monotonic, quasi-static (cyclic), and dynamic analyses are developed in this thesis. A new analytical model is developed to accurately represent connections between sheathing panels and wood framing members (sheathing-to-framing connections) in structural analysis computer programs. This new model represents sheathing–to–framing connections using an oriented pair of nonlinear springs. Unlike previous models, the new analytical model for sheathing-to-framing connections is suitable for both monotonic, cyclic, or dynamic analyses. Moreover, the new model does not need to be scaled or adjusted. The new analytical model may be implemented in a general purpose finite element program, such as ABAQUS, or in a specialized structural analysis program, such as CASHEW. The analytical responses of several shear walls and diaphragms employing this new model are validated against measured data from experimental testing. A less complex analytical model of shear walls and diaphragms, QUICK, is developed for routine use and for dynamic analysis. QUICK utilizes an equivalent single degree of freedom system that has been determined using either calibrated parameters from experimental or analytical data, or estimated sheathing-to-framing connection data. Application of the new analytical models is illustrated in two applications. In the first application, the advantages of diaphragms using glass fiber reinforced polymer (GFRP) panels in conjunction with plywood panels as sheathing (hybrid diaphragms) are presented. In the second application, the response of shear walls with improperly driven (overdriven)nails is determined along with a method to estimate strength reduction due to both the depth and the percentage of total nails overdriven.