Difference between revisions of "Category:756 Seismic Design"

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All new bridges on the state system include small details and design checks to resist earthquakes. In Seismic Performance Categories B, C and D, additional design and detailing work is needed because of the increased probability of damaging earthquakes.
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All new bridges on the state system shall include some level of seismic design and/or detailing to resist earthquakes based upon an expected seismic event for a given return period. For example, in Seismic Performance Categories B, C and D, both design and detailing work is needed because of the increased probability of damaging earthquakes.
 
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|[[Media:756 Visio-SeismicRetrofitFlow LFD.pdf|Bridge Seismic Design Process Flowchart]]
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When existing bridges in SPC B, C and D are identified as needing repairs or maintenance, a decision on whether to include seismic retrofitting in the scope of the project should be made based on the location of the bridge, the extent of the rehabilitation work and the expected life of the of the bridge after the work. For example, if the bridge needs painting or deck patching, no retrofitting is recommended. However, redecking or widening the bridge indicates that MoDOT is planning to keep the bridge in the state system with an expected life of at least 30 more years.  In these instances, the project core team should consider cost effective methods of retrofitting the existing bridge.
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[[image:756 seismic design.jpg|center|725px|thumb|<center>'''Examples of new and retrofit design features. Diagram is not to scale.'''</center>]]
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When existing bridges in SPC B, C and D are identified as needing repairs or maintenance, a decision on whether to include seismic retrofitting in the scope of the project should be made based on the location of the bridge, the extent of the rehabilitation work and the expected life of the bridge after the work. For example, if the bridge needs painting or deck patching, no retrofitting is recommended. However, redecking or widening the bridge indicates that MoDOT is planning to keep the bridge in the state system with an expected life of at least 30 more years.  In these instances, the project core team should consider cost effective methods of retrofitting the existing bridge.

Revision as of 11:53, 23 March 2009

All new bridges on the state system shall include some level of seismic design and/or detailing to resist earthquakes based upon an expected seismic event for a given return period. For example, in Seismic Performance Categories B, C and D, both design and detailing work is needed because of the increased probability of damaging earthquakes.

Seismic Performance Categories
St. Louis Area
Bridge Seismic Design Process Flowchart

 

 


When existing bridges in SPC B, C and D are identified as needing repairs or maintenance, a decision on whether to include seismic retrofitting in the scope of the project should be made based on the location of the bridge, the extent of the rehabilitation work and the expected life of the bridge after the work. For example, if the bridge needs painting or deck patching, no retrofitting is recommended. However, redecking or widening the bridge indicates that MoDOT is planning to keep the bridge in the state system with an expected life of at least 30 more years. In these instances, the project core team should consider cost effective methods of retrofitting the existing bridge.