Ryoji Iwasaki

Probability-based seismic safety evaluation of existing buildings

A probabilistic second-moment seismic safety measure is proposed and the seismic safety of eleven existing buildings is evaluated. These buildings are analyzed using lumped-mass models and the seismic hazard at each building site is estimated by utilizing an available probability-based seismic hazard map. Results for the distribution of the safety measure with story level suggest that significant damage may be concentrated only in a few stories in some buildings. Second-moment seismic margin indices for some buildings are relatively high, while lower seismic margins result for others, perhaps due to underestimation of the ultimate limit state resistance. The feasibility of the procedure for evaluating seismic safety of existing buildings is demonstrated.

Flow simulation by wind tunnel with computer-controlled multiple fans

Abstract This paper presents the simulation of turbulent flow by controlling multiple fans in a two-dimensional wind tunnel. The main purposes of this study are to generate a large turbulence scale and simulate a turbulent flow fitted to specified power spectrum and co-coherence in a low frequency range, both of which are not easily accomplished only by the means of roughness blocks, spires and grids. It was relatively easy to obtain a large turbulence scale by controlling multiple fans numerically. According to the proposed procedure, turbulent characteristics of wind flow were successfully simulated to satisfy a specified condition for the target power spectrum and co-coherence.