Seismic Ground Motion Amplifications Estimated by Means of Spectral Ratio Techniques: Examples for Different Geological and Morphological Settings

This paper presents the performance of base-isolated steel structures under the seismic load. The main goals of this study are to evaluate the effectiveness of base isolation systems for steel structures against earthquake loads; to verify the modal analysis of steel frame compared with the hand calculation results; and development of a simulating method for base-isolated structure’s responses. Two models were considered in this study, one a steel structure with base-isolated and the other without base-isolated system. The nonlinear time-history analysis of both structures under El Centro 1940 seismic ground motion was used based on finite element method through SAP2000. The mentioned frames were analyzed by Eigenvalue method for linear analysis and Ritz-vector method for nonlinear analysis. Simulation results were presented as time-acceleration graphs for each story, period and frequency of both structures for the first three modes.

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Non-stationary stochastic vector processes: seismic ground motion applications

Probabilistic Engineering Mechanics ◽

10.1016/0266-8920(96)00007-0 ◽

1996 ◽

Vol 11 (3) ◽

pp. 149-167 ◽

Cited By ~ 231

Author(s):

George Deodatis

Keyword(s):

Ground Motion ◽

Seismic Ground Motion ◽

Stochastic Vector

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Near-Source Simulation of Strong Ground Motion in Amatrice Downtown Including Site Effects

Geosciences ◽

10.3390/geosciences11050186 ◽

2021 ◽

Vol 11 (5) ◽

pp. 186

Author(s):

Alessandro Todrani ◽

Giovanna Cultrera

Keyword(s):

Ground Motion ◽

Site Effects ◽

Central Italy ◽

Strong Motion ◽

Seismic Source ◽

Spectral Ratio ◽

Intensity Measures ◽

Standard Spectral Ratio ◽

Heavy Damage ◽

Strong Ground

On 24 August 2016, a Mw 6.0 earthquake started a damaging seismic sequence in central Italy. The historical center of Amatrice village reached the XI degree (MCS scale) but the high vulnerability alone could not explain the heavy damage. Unfortunately, at the time of the earthquake only AMT station, 200 m away from the downtown, recorded the mainshock, whereas tens of temporary stations were installed afterwards. We propose a method to simulate the ground motion affecting Amatrice, using the FFT amplitude recorded at AMT, which has been modified by the standard spectral ratio (SSR) computed at 14 seismic stations in downtown. We tested the procedure by comparing simulations and recordings of two later mainshocks (Mw 5.9 and Mw 6.5), underlining advantages and limits of the technique. The strong motion variability of simulations was related to the proximity of the seismic source, accounted for by the ground motion at AMT, and to the peculiar site effects, described by the transfer function at the sites. The largest amplification characterized the stations close to the NE hill edge and produced simulated values of intensity measures clearly above one standard deviation of the GMM expected for Italy, up to 1.6 g for PGA.

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