Ihatelawyers
Geotechnical
- Dec 3, 2010
- 15
Background
ASCE 7-10 Chapter 11 Seismic Design Criteria
11.1.2 Specifically excludes single family residences from the scope.
11.8.1 Specifically states that a structure assigned to Seismic Design Category E or F shall not be located where a known potential exists for an active fault to cause rupture (this limitation is NOT extended to SDC C or D).
11.8.2 requires that d. surface displacement due to faulting be investigated and evaluated & recommendations for mitigation presented.
2009 NEHRP - Resource Paper 12, presents the following when discussion Surface Fault Rupture Hazard
Mitigation of Surface Faulting Hazards..."where a surface faulting hazard exists, the site must be avoided or the structure must be designed to withstand ground deformation or surface fault rupture." It goes on to say you would be typically limited to only a few inches of fault displacement before the design becomes impractical.
I am in a jurisdiction with NO supplemental policies.
Questions:
1 - Is the exemption of 11.1.2 (and commentary) intended to impart that the requirements of 11.8.2 are not applicable to single family residential?
2 - Does the fact that 11.8.1 excludes SDC C and D indicate that SDC C and D structures can span a fault as long as the requirements of d. are met and mitigated?
3 - Does 2009 NEHRP support spanning a fault if surface displacement is less than a few inches? Seems like it.
Situation: I have a site with high likelihood that the property will be determined to be crossed by an active fault; the fault has a reported slip rate of 2 mm/yr +- (right lateral). We will have the site investigated by a qualified geologist. I'm just trying to digest what options my client may have and I have found ASCE 7-10 to not be as direct as I was hoping. Seems like our SDC D structure could span the fault if the geologist opines that the magnitude of surface displacement is relatively low.
I am also intrigued by the exemption of single family residences and whether or not that exemption extends to Section 11.8.2.
Thank you!
ASCE 7-10 Chapter 11 Seismic Design Criteria
11.1.2 Specifically excludes single family residences from the scope.
11.8.1 Specifically states that a structure assigned to Seismic Design Category E or F shall not be located where a known potential exists for an active fault to cause rupture (this limitation is NOT extended to SDC C or D).
11.8.2 requires that d. surface displacement due to faulting be investigated and evaluated & recommendations for mitigation presented.
2009 NEHRP - Resource Paper 12, presents the following when discussion Surface Fault Rupture Hazard
Mitigation of Surface Faulting Hazards..."where a surface faulting hazard exists, the site must be avoided or the structure must be designed to withstand ground deformation or surface fault rupture." It goes on to say you would be typically limited to only a few inches of fault displacement before the design becomes impractical.
I am in a jurisdiction with NO supplemental policies.
Questions:
1 - Is the exemption of 11.1.2 (and commentary) intended to impart that the requirements of 11.8.2 are not applicable to single family residential?
2 - Does the fact that 11.8.1 excludes SDC C and D indicate that SDC C and D structures can span a fault as long as the requirements of d. are met and mitigated?
3 - Does 2009 NEHRP support spanning a fault if surface displacement is less than a few inches? Seems like it.
Situation: I have a site with high likelihood that the property will be determined to be crossed by an active fault; the fault has a reported slip rate of 2 mm/yr +- (right lateral). We will have the site investigated by a qualified geologist. I'm just trying to digest what options my client may have and I have found ASCE 7-10 to not be as direct as I was hoping. Seems like our SDC D structure could span the fault if the geologist opines that the magnitude of surface displacement is relatively low.
I am also intrigued by the exemption of single family residences and whether or not that exemption extends to Section 11.8.2.
Thank you!