Reduction of effective resistance of nailed shear walls caused by misnailing - Monte Carlo simulations of the effective resistance

Practical effective;resistance of nailed shear walls is mostly less than th eir ideal resistance evaluated by standard tests or theoretical analyses, b ecause nailing on construction sites is often inadequate or irregular in co mparison with the careful nailing in the assemblies of test specimens. The objective of this study was to simulate the effective resistance of nailed shear walls probably reduced by insufficient side margins resulting from mi snailing. Monte Carlo simulations were conducted to estimate the effective resistance of nailed shear walls using the test results of nailed timber joints with wood-based panels, namely Douglas-fir plywood, OSB and MDF. Two assumptions were adopted in the Monte Carlo simulations. The first assu mption was that properly driven nails bad a regular lateral resistance, but any misdriven nail had no lateral resistance. The next assumption was that the irregular location of each nail was distributed normally and its later al resistance varied as affected by its side margin from the edge of the pa nel or the timber frame member. The simulations with the first assumption showed that the effective resista nce of nailed shear walls was reduced roughly as much as the probability of misdriven nails, if the floor diaphragms fixed to the shear walls had suff icient shear stiffness. The effective resistance of nailed shear walls seem ed to depend on the shear stiffness of floor diaphragms. The simulations with the second assumption showed that the reduction of the initial stiffness of shear walls due to irregular nailing was not critical but the maximum resistance and the ductility of them was reduced remarkabl y. This result indicated the importance of making sure of sufficient safety margin and ductility in laboratory tests, which could cover their probable reduction in actual timber constructions.