Rotational Restraint of Wood‐Stud Wall Supports

A computer program consisting of the finite‐element method, multilinear material models, and a linear step‐by‐step procedure that accounts for nonlinear behavior of wood materials, nailed joints, and intercomponent gaps was developed for predicting the structural behavior of the connection system between wall, floor, and foundation in wood‐frame buildings. The program enabled evaluation of support restraint that reduces wall deflection and exploration of simple construction modifications that increase restraint. Model accuracy was verified by first testing and then theoretically modeling and analyzing nine wall panels; predicted deflections closely agreed with corresponding experimental values. Application of the program showed that deflection reduction due to restraint was less than 2% for conventional walls but could be increased to 13% by hammering two additional 6d nails per stud into plywood sheathing and sill plate and six additional 6d nails per stud into plywood sheathing and header. To provide data for design, coefficients of support restraint were evaluated for nine typical construction details each modified seven times; two sets of coefficients are presented, one for moderate wind pressures up to $50\mathrm{psf}(2.39\mathrm{kN}/m^2)$ and another for severe wind pressures of $150\mathrm{psf}(7.19\mathrm{kN}/m^2)$ or more. The additional nailing not only increases wall stiffness, thereby reducing deflection, but also provides better resistance of light‐frame wood buildings to earthquakes and the uplift pressures of tornadoes and hurricanes.