Tsunami loading on light-frame wood structures

Graduation date: 2012Since 2004 there have been multiple devastating tsunamis around the globe triggered by large magnitude earthquakes; with the most recent being the Tohoku, Japan tsunami in March 2011. These tsunamis have caused significant loss of life and damage to the coastal communities impacted by these powerful waves. The resulting devastation has raised awareness of the dangers of tsunamis and the Network for Earthquake Engineering Simulation (NEES) housesmash project (NEEShousesmash), was started to investigate several different areas of tsunami inundation. The work presented in the following two manuscripts was performed at the O.H. Hinsdale Wave Lab and Gene D. Knudson Wood Engineering Lab, which are located at Oregon State University. This work represents a small portion of the total NEEShousesmash project, and is focused on improving the knowledge and predictability of tsunami loading and structural performance.\ud The first manuscript investigates tsunami wave impact on full scale light-frame wood walls, and compares the measured forces to calculated values using the linear momentum equation, previously evaluated by Cross (1967). The results show for each wave height tested a peak transient force followed by a sustained quasi-static force, with a ratio of transient force to quasi-static force of 2.2. The results also show that the linear momentum equation did an acceptable job of predicting the measured transient forces on the walls to within ±10%, and that increased wall flexibility, 2x4 vs. 2x6 dimensional lumber, resulted in lower measured transient forces when subjected to similar tsunami wave heights. These results are important for practical use because the linear momentum equation is a simple equation to use, that only requires a couple of site specific input variables.\ud The second manuscript is a continuation of the work done in the wave lab for the first manuscript. These experiments provide a starting point for expanding the testing of the structural response and performance of larger scale structures subjected to tsunami wave loads. By simulating tsunami loading in a traditional structures laboratory, the inherent limits of testing structural performance in small scale tsunami laboratory facilities is removed. The results show that a light-frame wood shear wall, built to current standards, is susceptible to premature failures from concentrated impact loads at intermediate heights compared to the design strength at full height. It is also shown that the out-of-plane walls subjected to both elastic and inelastic loads behave like a one way slab with minimal load sharing between adjacent studs. The failures observed during the hydrodynamic wave testing of the nailed connection between the bottom plate and studs was successfully reproduced, and shows that current construction standards are not fully utilizing the available capacity of each stud when subjected to tsunami waves. The reinforcement of this connection with traditional metal brackets would help increase the capacity of the out-of-plane wall to resist tsunami wave loads