Mar. 01, 2021



To be held on Monday, March 1st, 2021, 12:10-13:00

via zoom meeting - link


VS30 for Site Response – use, misuse, and how we can do better than that within the Israeli building code


Ronnie Kamai


Dept. of Civil and Environmental Engineering, BGU



Site response is a term describing the effect of the local shallow geology on surface ground motions. Soft soil sites may amplify the motions by factors of 2 and even up to 10. Hence, this is one of the most significant effects in seismic hazard analysis and is therefore a critical component in ground motion prediction equations (GMPEs) as well as in local building codes. While the site response depends on the mechanical properties of the soil layers comprising the full velocity profile between the bedrock and the surface, it is often evaluated with simplified predictors, or proxies. VS30, the time-averaged shear-wave velocity in the upper 30m, is one of the most popular proxies, adopted by many GMPEs worldwide, as well as by the local Israeli building code (SI413). However, many studies debate its capability to evaluate site effects as a single proxy and suggest the use of complementary or alternative parameters.

In this talk, I will review the origin of VS30, as well as common misconceptions about its use and misuse, using mostly global data from different regions. I will then present a parametric model, developed specifically for Israel, that improves greatly on the current practice within the Israeli building code. The presented work is based on a large database of velocity profiles, used to compute expected amplifications and test the capability of different proxies to evaluate site-response in Israel.



About the speaker:

Ronnie Kamai is a senior lecturer in the Dept. of Civil and Env. Eng. at BGU. She joined the department in 2013, after completing a post-doctoral fellowship at the Pacific Earthquake Engineering Research center (PEER) in Berkeley, California. During her post-doctoral fellowship, Dr. Kamai worked with the Next Generation Attenuation (NGA) team to develop ground motion prediction and site-response models. She obtained her Ph.D. in Geotechnical Engineering, from the university of California, Davis, working on liquefaction-induced strength-loss, using both experiments and numerical tools. Her B.Sc. and M.Sc. are from the department of Geological and Environmental Sciences at BGU. Dr. Kamai's research focus is related to seismic-hazard analysis, ground-motion evaluation, site-response, and fundamental soil mechanics. ​