Empirical Evaluation of Kinematic Soil-Structure Interaction Effects in Structures with Large Foundation Footprint and Deep Embedment Depth

Session: Near-Surface Effects: Advances in Site Response Estimation and Its Applications [Poster]
Type: Poster
Date: 4/28/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Recorded earthquake motions at geotechnical downhole arrays and adjacent instrumented structures can be a valuable source of information to evaluate the extent of Soil-Structure Interaction (SSI) phenomenon. Kinematic SSI effects result from the presence of stiff foundation on or in the ground, which causes foundation motions (FM) to deviate from free-field motions (FFM), mainly due to base slab averaging and embedment effects in the absence of structure and foundation inertia. It has become increasingly common for structural engineers to take advantage of kinematic interaction effects to reduce FM relative to those specified in the free-field. Based on ASCE 41-17, kinematic interaction effects shall be permitted to be calculated for regular structures through either explicit modeling using advanced simulation software packages, which can account for spatial and depth variations in ground motions but relatively costly or simplified models which are mainly semi-empirical. The simplified models have been calibrated only for regular buildings in terms of foundation width and depth of embedment. As a result, their applications in structures with much larger foundation footprint size and deeper embedment depth such as nuclear power plants (NPP) can be questionable. In this study, a dataset of earthquake motions at the Kashiwazaki-Kariwa Nuclear Power Plant (KKNPP) during the 2007 Niigata-Chuetsu Earthquake was used to calculate the ratio of response spectra (RRS) between FM and corresponding FFM and compare with the suggested RRS based on ASCE 41-17. For this purpose, at first, data with 50 pairs of FM and FFM were processed and RRS were calculated. Different spectral analysis methodologies were examined and their effects on the results are discussed. Comparison is performed between the empirical and recommended RRS based on ASCE 41-17 followed by discussions on its applicability to the NPP structures which are unique in terms of dimensions and dynamic characteristics.

Presenting Author: Ramin Motamed

Authors