300 likes | 413 Views
NEES Quake Summit Thursday July 12, 2012 Seismic Design In Massachusetts. 0.06. Eric M. Hines Principal, LeMessurier Consultants, Boston Professor of Practice, Tufts University. UBC 1970-1973. OCBF: V = 1820k SMRF: V = 753k. UBC 1976-1985. OCBF: V = 3067k SMRF: V = 1149k.
E N D
NEES Quake Summit Thursday July 12, 2012 Seismic Design In Massachusetts 0.06 Eric M. Hines Principal, LeMessurier Consultants, Boston Professor of Practice, Tufts University
UBC 1970-1973 OCBF: V = 1820k SMRF: V = 753k
UBC 1976-1985 OCBF: V = 3067k SMRF: V = 1149k
ATC 3-06 1978; MSBC 1997 OCBF: V = 1152k SMRF: V = 497k
IBC 2006 (USGS 2002); MSBC 2008 2% in 50 year, Sa for T = 1.0s 0.06 OCBF: V = 985k SMRF: V = 273k
LA/Bos 1.0 1.33 4.0 3.5-6.5 SMRF OCBF UBC 1970-1973 753 1820 UBC 1976-1985 1149 3067 ATC 3-06 1978; MSBC 1997 10% in 50 year 497 1152 IBC 2006 (USGS 2002); MSBC 2008 2% in 50 year 273 985
Oakland San Jose San Francisco San Bernardino Vallejo Northridge Concord Riverside San Mateo Santa Rosa Santa Cruz
Hines , Baise and Swift (JSE—2011) (Prof. L.G. Baise, Tufts University) Site Class D: 1996 Maps = Category C 2002 Maps = Category B new Mass Code maintains special provisions based on 40 years of practice Vsavg = 695 ft/s soil profile adapted from: E.G. Johnson, “Geotechnical Characteristics of the Boston Area,” Civil Engineering Practice, 1989
Hines , Appel and Cheever (EJ—2009) 9-Story Concentrically Braced Frame
Hines & Fahnestock (Toronto—2010) Reserve System Concept
For R=3 systems MCE seismic forces are 4.5 times higher, but in the East, wind almost always controls drift. Braced Frame with Reserve System or Moment Frame with Stiffening System
1927 Steel Frame Building
3700 kips of shear capacity at Level 21 (244’)
Hines , Baise and Swift (JSE—2011) Eastern Suite, Site Class B
3/R=3 T=.69s 6/R=3 T=1.35s 9/R=3 T=2.07s 12/R=3 T=2.94s Hines , Baise and Swift (JSE—2011) NUREG Suite Amplified via Boston Stiff Soil Profile Sa (g) Period, T (sec)
Hines , Appel and Cheever (EJ—2009) First Story Drift for 6-Story Models under GM6
Hines , Appel and Cheever (EJ—2009) Behavior of 6-Story/R3 Model under GM5
R=2 R=3 R=4 WRS Hines , Appel and Cheever (EJ—2009) 9-Story Fragility Curves
R=2 R=3 R=4 WRS 3-Story Fragility Curves
1-Story Low-Ductility CBF+Reserve System 2 x Reserve 1/2 x Reserve
Future Practice • Reserve capacity is a clear concept (belt and suspenders), so designers can make sense of what they are doing. • R = 3*, R = 5/5, WRS, Stiffened MRF