Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches

Ballistic projectiles are the most frequently lethal volcanic hazard close to the vent. Recent eruptions of Ontake in 2014 and Kusatsu-Shirane in 2018 showed that un-reinforced, timber-framed buildings - those typically considered highly vulnerable to the dangerous penetration of ballistics - provid...

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Main Authors: Williams, George T., Kennedy, Ben M., Lallemant, David, Wilson, Thomas M., Allen, Nicole, Scott, Allan, Jenkins, Susanna F.
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/137188
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1371882023-02-28T16:40:57Z Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches Williams, George T. Kennedy, Ben M. Lallemant, David Wilson, Thomas M. Allen, Nicole Scott, Allan Jenkins, Susanna F. Asian School of the Environment Earth Observatory of Singapore Science::Geology Volcano Volcanic Hazards Ballistic projectiles are the most frequently lethal volcanic hazard close to the vent. Recent eruptions of Ontake in 2014 and Kusatsu-Shirane in 2018 showed that un-reinforced, timber-framed buildings - those typically considered highly vulnerable to the dangerous penetration of ballistics - provided life-saving shelter from ballistic impact. Modelled kinetic energies of some non-penetrating impacts were an order of magnitude above expected penetration thresholds. It has been hypothesised that a pre-existing layer of tephra on the roofs cushioned impacts. To quantitatively test this, and improve our understanding of how buildings respond to projectile impacts, we used a pneumatic cannon to simulate block impacts to clay tiles and reinforced concrete roof slabs covered with tephra layers 0–20 cm thick. Substantially higher impact energies were resisted when tephra was present with 5 cm of tephra approximately tripling the penetration threshold of both building materials. Fragility curves, which relate ballistic hazard intensity with the probability of building damage, were developed from our experimental data following three curve fitting approaches: generalised link models, cumulative link models and data binning. A key benefit of these approaches is that confidence in these curves can be robustly quantified from the data – the first time that this has been attempted for volcanic fragility curves. This study shows how the extent of building damage can be strongly influenced by the sequence of volcanic hazards and provides an example of proactive risk management through testing of physical mitigation strategies in a laboratory environment. Published version 2020-03-05T07:58:28Z 2020-03-05T07:58:28Z 2019 Journal Article Williams, G. T., Kennedy, B. M., Lallemant, D., Wilson, T. M., Allen, N., Scott, A., & Jenkins, S. F. (2019). Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches. Journal of Volcanology and Geothermal Research, 388, 106711. doi:10.1016/j.jvolgeores.2019.106711 0377-0273 https://hdl.handle.net/10356/137188 10.1016/j.jvolgeores.2019.106711 2-s2.0-85075464648 388 106711 en Journal of Volcanology and Geothermal Research 10.21979/N9/8XERMI © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Geology
Volcano
Volcanic Hazards
spellingShingle Science::Geology
Volcano
Volcanic Hazards
Williams, George T.
Kennedy, Ben M.
Lallemant, David
Wilson, Thomas M.
Allen, Nicole
Scott, Allan
Jenkins, Susanna F.
Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
description Ballistic projectiles are the most frequently lethal volcanic hazard close to the vent. Recent eruptions of Ontake in 2014 and Kusatsu-Shirane in 2018 showed that un-reinforced, timber-framed buildings - those typically considered highly vulnerable to the dangerous penetration of ballistics - provided life-saving shelter from ballistic impact. Modelled kinetic energies of some non-penetrating impacts were an order of magnitude above expected penetration thresholds. It has been hypothesised that a pre-existing layer of tephra on the roofs cushioned impacts. To quantitatively test this, and improve our understanding of how buildings respond to projectile impacts, we used a pneumatic cannon to simulate block impacts to clay tiles and reinforced concrete roof slabs covered with tephra layers 0–20 cm thick. Substantially higher impact energies were resisted when tephra was present with 5 cm of tephra approximately tripling the penetration threshold of both building materials. Fragility curves, which relate ballistic hazard intensity with the probability of building damage, were developed from our experimental data following three curve fitting approaches: generalised link models, cumulative link models and data binning. A key benefit of these approaches is that confidence in these curves can be robustly quantified from the data – the first time that this has been attempted for volcanic fragility curves. This study shows how the extent of building damage can be strongly influenced by the sequence of volcanic hazards and provides an example of proactive risk management through testing of physical mitigation strategies in a laboratory environment.
author2 Asian School of the Environment
author_facet Asian School of the Environment
Williams, George T.
Kennedy, Ben M.
Lallemant, David
Wilson, Thomas M.
Allen, Nicole
Scott, Allan
Jenkins, Susanna F.
format Article
author Williams, George T.
Kennedy, Ben M.
Lallemant, David
Wilson, Thomas M.
Allen, Nicole
Scott, Allan
Jenkins, Susanna F.
author_sort Williams, George T.
title Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
title_short Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
title_full Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
title_fullStr Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
title_full_unstemmed Tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
title_sort tephra cushioning of ballistic impacts : quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches
publishDate 2020
url https://hdl.handle.net/10356/137188
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