Assessing, Coding, and Marking of Highway Structures in Emergency Situations, Volume 2: Assessment Process Manual (2016) / Chapter Skim
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From page 11... ...
11 C H A P T E R 2 2.1 Introduction This section provides an overview of emergency events that can result in significant damage to highway structures in the United States. The emergency events include earthquake, tsunami, tornado, high winds, hurricane and storm surge, flooding, scour, and fire.
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12 Assessing, Coding, and Marking of Highway Structures in Emergency Situations: Assessment Process Manual 2.2 Warning Systems In this section, warning systems for several emergency events will briefly be discussed. Warning systems vary significantly in their degree of accuracy and delay before response due to the unpredictable nature of emergency events.
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Emergency Events 13 2.3 Earthquakes An earthquake is defined as a violent and sudden shaking of the ground as a result of movements within the earth's crust or volcanic action. Earthquake seismic waves create multi-directional ground motions, which create displacements/deformations and forces/stresses within highway structures.
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14 Assessing, Coding, and Marking of Highway Structures in Emergency Situations: Assessment Process Manual Structure Vulnerability to Earthquake Bridges • Vulnerable bridge types susceptible to earthquake damage include the following (Arkansas DOT 2008) : – Simple span structure or units supported on non-seismic bearings, and narrow bearing seats.
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Emergency Events 15 Highway structures are particularly vulnerable to the initial wave; the runup and drawdown flows; and the associated hydraulic/hydrodynamic, debris, and scour impacts. The complex impact and damage for transportation structures can be found in the field reports (EERI 2011, Francis and Yeh 2006)
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16 Assessing, Coding, and Marking of Highway Structures in Emergency Situations: Assessment Process Manual Besides the wind gust loading on transportation structures, one of the most damaging aspects of tornados in regards to highway structures is impact from wind-borne debris. Tornado wind speeds can exceed 300 mph and can lift houses, motor vehicles, and trees moving them over 100 yards.
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From page 17... ...
Emergency Events 17 to coastal regions, but tropical, cyclone-generated storm surges are among the most costly and deadly natural emergency events to affect the United States (Needham and Keim 2012)
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18 Assessing, Coding, and Marking of Highway Structures in Emergency Situations: Assessment Process Manual well-established principle in the design of almost all above-ground structures to make allowance for wind pressures. This design criterion makes highway structures particularly safe against wind loading.
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Emergency Events 19 incorporates storm surge as a component of each scale category. Storm Surge Interactive Risk Mapping being developed by the NOAA uses a simulation model (SLOSH)
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20 Assessing, Coding, and Marking of Highway Structures in Emergency Situations: Assessment Process Manual 2.10 Fire Bridge fire is usually caused by vehicle crashes that result in gasoline burning or flammable chemical incidents in the vicinity of highway bridges. Gasoline fire is much more severe than regular building fire and is usually characterized by high heating rate and peak temperature.
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