Estimation of time-averaged shear wave velocity (swv) to 30 m considering site swv structural characteristic

Abstract

The time-averaged shear wave velocity (SWV) to 30 m (V S30 ) is a site condition parameter that has been widely used to specify the site class in building codes. However, the penetration depth of some building sites is less than 30 m, and thus, V S30 cannot be determined based on the velocity profiles. To estimate the site parameter V S30 accurately, we examined the effect of the velocity structural characteristic parameter of site profiles, β H , on V S30 by performing a residual analysis. Further, a method to estimate V S30 was established considering the effect of β H , and the validity of the proposed model was assessed based on site data pertaining to Japan and California (USA). The results show that the time-averaged shear wave velocity to the depth H (H < 30 m), V SH , is weakly correlated with the parameter β H . However, β H has a significant effect on V S30 ; for the same site V SH , V S30 tended to increase with β H . Compared with the extrapolation method, the proposed model can significantly reduce the standard deviation for the estimation of V S30 , while increasing the correlation between the estimated and measured values of V S30 . Thus, the estimation accuracy can be significantly improved by considering the effect of β H .