Collapse Testing and Analysis of a Light-Frame Wood Garage Wall

Abstract

Light-frame wood (woodframe) buildings have been tested at full-scale sparingly around the world, primarily due to the cost associated with such testing and a general lack of facilities large enough to test at system level. The data from the tests that have been performed are used to help develop nonlinear time history analysis models that can predict the behavior of woodframe buildings during strong ground shaking. It is difficult to test buildings to the point of collapse because such tests can damage costly test equipment, i.e., the shake table. This paper presents the results of a dynamic collapse test on a light-frame wood garage wall and the results of a numerical model to simulate the wall behavior all the way to the collapse point. The tested wall was heavily damaged as a result of subjecting it to a ground motion recorded during the 1995 Kobe earthquake. Then, 85% of a near-fault ground motion recording from the Northridge earthquake was used, which immediately collapsed the test specimen. A specialized wood shear wall analysis program, formulated using a corotational formulation and large deformation theory, was utilized to model the garage wall. The numerical model provided a good prediction (predicted the peak wall displacements to within 15% of the measured values), but as a direct result of the observed failure mechanism of the wall, it was determined that additional contact elements were needed in the model. Failure was observed at the sill plate of the garage wall returns and also in the sheathing due to a moment failure where the header connected to the wall returns. Finally, it was observed that variability in the stiffness of the hold-down connections has a significant influence on the uplift predictions.