Full 3D integration of site-city effects in regional scale earthquake simulations

Ricardo Taborda, & Jacobo Bielak

Published 2011, SCEC Contribution #1472

This article presents results from a study assessing the effects of the built environment on the ground motion during earthquakes, and the dynamic response of buildings considering multiple, simultaneous soil-foundation-structure interaction effects. Using Hercules---the octree-based finite-element earthquake simulator developed by the Quake group at Carnegie Mellon University---we have implemented new computational modules that allow us to incorporate large inventories of idealized building models in earthquake simulations at a regional scale, using parallel supercomputers. The buildings and their foundations are modeled as rectangular prismatic blocks filled with a homogeneous material whose properties are set so that the fundamental dynamic properties of the real structures are matched on average. These models consist of the same solid finite-elements as those used for the crustal structure, and are in full contact with the soil. We test our implementation with an inventory of 74 buildings placed near the edge of a realistic basin. Results indicate that the presence of the built environment changes considerably the ground motion in the `city' and within a perimeter of 300 to 500~m. In particular, we observe significant changes in the spatial variability of the ground response. This also affects the response of the buildings, which is in general reduced due to soil-structure interaction effects. This study suggests that larger inventories of buildings may have the potential of drastically changing the local and regional ground response during earthquakes, confirming aspects known from previous, though limited studies, at a fully integrated 3D and regional level not explored before.

Taborda, R., & Bielak, J. (2011). Full 3D integration of site-city effects in regional scale earthquake simulations. Oral Presentation at 8th International Conference on Structural Dynamics.