Near-Field Ground Motion Modal versus Wave Propagation Analysis

The response spectrum generally provides a good estimate of the global displacement and acceleration demand of far-field ground motion on a structure. However, it does not provide accurate information on the local shape or internal deformation of the response of the structure. Near-field pulse-like...

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Main Author: Artur Cichowicz
Format: Article
Language:English
Published: Wiley 2010-01-01
Series:Shock and Vibration
Online Access:http://dx.doi.org/10.3233/SAV-2010-0552
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author Artur Cichowicz
author_facet Artur Cichowicz
author_sort Artur Cichowicz
collection DOAJ
description The response spectrum generally provides a good estimate of the global displacement and acceleration demand of far-field ground motion on a structure. However, it does not provide accurate information on the local shape or internal deformation of the response of the structure. Near-field pulse-like ground motion will propagate through the structure as waves, causing large, localized deformation. Therefore, the response spectrum alone is not a sufficient representation of near-field ground motion features. Results show that the drift-response technique based on a continuous shear-beam model has to be employed here to estimate structure-demand parameters when structure is exposed to the pulse like ground motion. Conduced modeling shows limited applicability of the drift spectrum based on the SDOF approximation. The SDOF drift spectrum approximation can only be applied to structures with smaller natural periods than the dominant period of the ground motion. For periods larger than the dominant period of ground motion the SDOF drift spectra model significantly underestimates maximum deformation. Strong pulse-type motions are observed in the near-source region of large earthquakes; however, there is a lack of waveforms collected from small earthquakes at very close distances that were recorded underground in mines. The results presented in this paper are relevant for structures with a height of a few meters, placed in an underground excavation. The strong ground motion sensors recorded mine-induced earthquakes in a deep gold mine, South Africa. The strongest monitored horizontal ground motion was caused by an event of magnitude 2 at a distance of 90 m with PGA 123 m/s2, causing drifts of 0.25%–0.35%. The weak underground motion has spectral characteristics similar to the strong ground motion observed on the earth's surface; the drift spectrum has a maximum value less than 0.02%.
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spelling doaj-art-bbf4be3bab06498983774d7ced2a93092025-02-03T01:12:52ZengWileyShock and Vibration1070-96221875-92032010-01-01174-561161710.3233/SAV-2010-0552Near-Field Ground Motion Modal versus Wave Propagation AnalysisArtur Cichowicz0Council for Geoscience, Pretoria, South AfricaThe response spectrum generally provides a good estimate of the global displacement and acceleration demand of far-field ground motion on a structure. However, it does not provide accurate information on the local shape or internal deformation of the response of the structure. Near-field pulse-like ground motion will propagate through the structure as waves, causing large, localized deformation. Therefore, the response spectrum alone is not a sufficient representation of near-field ground motion features. Results show that the drift-response technique based on a continuous shear-beam model has to be employed here to estimate structure-demand parameters when structure is exposed to the pulse like ground motion. Conduced modeling shows limited applicability of the drift spectrum based on the SDOF approximation. The SDOF drift spectrum approximation can only be applied to structures with smaller natural periods than the dominant period of the ground motion. For periods larger than the dominant period of ground motion the SDOF drift spectra model significantly underestimates maximum deformation. Strong pulse-type motions are observed in the near-source region of large earthquakes; however, there is a lack of waveforms collected from small earthquakes at very close distances that were recorded underground in mines. The results presented in this paper are relevant for structures with a height of a few meters, placed in an underground excavation. The strong ground motion sensors recorded mine-induced earthquakes in a deep gold mine, South Africa. The strongest monitored horizontal ground motion was caused by an event of magnitude 2 at a distance of 90 m with PGA 123 m/s2, causing drifts of 0.25%–0.35%. The weak underground motion has spectral characteristics similar to the strong ground motion observed on the earth's surface; the drift spectrum has a maximum value less than 0.02%.http://dx.doi.org/10.3233/SAV-2010-0552
spellingShingle Artur Cichowicz
Near-Field Ground Motion Modal versus Wave Propagation Analysis
Shock and Vibration
title Near-Field Ground Motion Modal versus Wave Propagation Analysis
title_full Near-Field Ground Motion Modal versus Wave Propagation Analysis
title_fullStr Near-Field Ground Motion Modal versus Wave Propagation Analysis
title_full_unstemmed Near-Field Ground Motion Modal versus Wave Propagation Analysis
title_short Near-Field Ground Motion Modal versus Wave Propagation Analysis
title_sort near field ground motion modal versus wave propagation analysis
url http://dx.doi.org/10.3233/SAV-2010-0552
work_keys_str_mv AT arturcichowicz nearfieldgroundmotionmodalversuswavepropagationanalysis