This thesis presents a numerical study of the influence of varying story strength on the seismic performance of multi-story wood-frame shear wall buildings. In the prior FEMA P695 studies of these buildings, the non-simulated collapse limit-state was exceeded primarily in the first story. This observation raised interest in quantifying the influence of varying strength from story to story on seismic response.

In this study, four distributions of strength are used as bounding cases. The Parabolic strength distribution (1) results from the ELF vertical force distribution method in ASCE 7 that assigns forces to each level based on weight and story height. The Triangular strength distribution (2) results from an assumed vertical force distribution that assigns lateral forces based on the seismic weight at each level. The Constant strength distribution (3) results from an assumed vertical force distribution that assigns a concentrated lateral force at the uppermost level based on the total seismic weight of all levels. The Baseline distribution (4) reflects a realistic vertical strength distribution resulting from the ELF vertical force distribution method.

The FEMA P695 methodology, which quantifies seismic performance via adjusted collapse margin ratios, is employed in this study. The analytical models include P-Delta effects and utilize the 10-parameter hysteresis CASHEW model. It is observed that the Parabolic strength distribution allows for dissipation of energy over the height of the building, has less collapse risk than other strength distributions studied, and reduces occurrence of concentrated deformations in a single story from the onset of applied lateral force.