CEE 289: Random Vibrations Introduction
Seismically Enhanced Non-Structural Partition Walls for Unibody
Residential Construction
Quake Summit 2012The George E. Brown Network for Earthquake
Engineering Simulation (NEES)July 12th, 2012
Gregory Deierlein (PI)Eduardo Miranda (Co-PI)Scott
SwensenStanford UniversityBenjamin Fell (Co-PI)Amy
HopkinsCalifornia State University, Sacramento
# #1S. SwensenIntroductionTraditional light-weight framed
structures:provide a high degree of life safety
are vulnerable to costly earthquake damageAbout $20 billion in
losses occurred to light-frame residential structures during the
Northridge Earthquake
can lead to many displaced persons when damagedThe 1994
Northridge Earthquake destroyed or heavily damaged 60,000 housing
units
www.impactlab.net/wp-content/uplopads/2010/03/fiolmore-house.jpg
#S. Swensen2
R = 2Conventional Light-Frame ConstructionCurrent design
methodology:Design structural walls (i.e. plywood or OSB) to resist
entire design lateral loadsAdd architectural finishes such as
gypsum partitions and stucco cladding, neglecting or heavily
discounting lateral
resistancewww.nhmodularhomes.com/house_cut_away.htmR = 6.5DBE,
6.5DBE, 2VR = 6.5VR = 2VDBEVR = 6.5R = 2Created by E. Miranda #S.
Swensen3Conventional Light-Frame ConstructionThis design approach
creates problems because in light framed construction, the ultimate
load is achieved at large and damaging drifts
www.flickr.com/photos/encouragement/3566839185
onset of damage 0.2% driftpeak lateral strength 2% drift
#S. Swensen4Opportunities to Improve Light-Frame
ConstructionAlternate design methodology:
Design structural and architectural building components to work
together in a unibody manner to resist earthquake loads and
deformations
This method is economical because finishes wouldnt have to be
added, they just must be better integrated into the structural
system
www.imperialclub.com/Yr/1966/SpottersGuide/index.htm
majesticspeed.com/wp-content/uploads/2010/12/Car-Unibody.jpg #S.
Swensen5Opportunities to Improve Light-Frame ConstructionThis
approach makes sense for light-framed buildings because:low-rise
framed structures are lightwall area is plentiful increased
strength is inexpensivestructural and architectural components are
integralmost components are drift sensitivefor short period
buildings, drifts are especially sensitive to lateral strength and
stiffness
Ruiz-Garcia and Miranda 2003
#S. Swensen6
Unibody Design ConceptDesign spectrum for Los Angeles, site
class D, 5% dampingR/Conventional Framed BuildingR = 6.5 = 3CR 1.6
(FEMA 440)Enhanced Framed BuildingR = 1 = 1CR 1
CR #S. Swensen7Research ObjectivesDevelop improved limited
ductility light-frame design concepts which increase lateral
structural strength and stiffness in an economical manner
Create and verify computational models that evaluate the seismic
performance of enhanced unibody systems
Formulate design methods and tools that consider (1) life safety
and (2) life cycle costs and loss of building functionality during
seismic events
Develop cost-effective base isolation systems for low-rise light
framed structures in areas of high seismic hazard
#S. Swensen8Components of Light-framed Walls
Sheathing-to-framing FastenerFlat Panel JointEdge Panel
JointFinished WallConventional mechanical fastenersNovel mechanical
fasteners (Maxiscrew by Ben Schmid)Adhesive fastening systems
#9S. Swensen
Mechanical Fastener Tests Type X GWB
= 1.3 mm(0.05) = 2.2 mm (0.09) = 3.2 mm (0.13) = 5.2 mm (0.20) =
10 mm (0.40) = 25 mm (1.00)
+16%Monotonic Backbone #S. Swensen10
Adhesive Gypsum-to-Wood Connections+4.9x+5.5x
Monotonic Backbone
#S. Swensen11
Adhesive Gypsum-to-Steel Connections+2.9x+4.7x Monotonic
Backbone
#Delete this slide?S. Swensen12
Sheathing-to-framing FastenerFlat Panel JointEdge Panel
JointFinished Wall
Components of Light-frame Residential StructuresConventional
wall with coarse threaded screwsWall with enhanced mechanical
fastersWall with adhesive fastening and enhanced screws
Finished Wall #13S. Swensen
Gypsum Sheathed Wall Tests Wood FramingCyclic loading of 1.22 m
(4 ft) square wallsCoarseThreaded ScrewsAdhesive + ScrewsEnhanced
Fasteners
#S. Swensen14
Gypsum Sheathed Wall Tests Wood Framing
++90%+4.2xCyclic SkeletonIBC/SDPWS Value (LRFD)
SDR = 0.21%SDR = 0.42%SDR = 0.63%SDR = 0.94%SDR = 2.0% #S.
Swensen15
Gypsum Sheathed Wall Tests Steel Framing+Cyclic Skeleton
#S. Swensen16Ongoing Testing of Gypsum and Stucco Clad
WallsCyclic loading of 2.44 m (8 ft) tall walls is currently being
carried out.Testing variables include:sheathing (gypsum &
stucco) and framing (wood and steel) materialuse of adhesiveswall
perforations and geometrypresence and configuration of end
returnsconfiguration of holdowns and anchorages
#Finite Element Wall AnalysisFit hysteretic model to component
behavior for fasteners, adhesive, panel joints, and holdowns
Build framing and sheathing. Use modeled components to connect
elements
Individual fastenersPanel jointHoldowns and anchorages #Finite
Element Wall Analysis
4 x 4 wall, Adhesive + screwsCyclic Skeleton Curves #Current and
Future WorkLarger wall and room assembly tests to investigate the
effect of: wall-diaphragm interfacesintersecting wall jointswindow
and door openingsanchorages and holdown variationsbi-directional
loading
The results from these tests will inform a full-scale building
shake table test performed at the University of California, San
Diego
#Computational simulations of:sheathing-to-framing fasteners,
hold downs, and panel jointswall and wall assembliesfull building
systems
Create a new design methodology that considers limit states of
(a) collapse safety and (b) damage control. Consider:
life cycle costs, including savings from earthquake
insurancepotential deterioration caused by moisture, temperature
fluctuation, aging, etc.
T = 0.2 s.R/ = 2.17T = 0.15 s.R/ = 1SDR > 0.2%Porter., K. et
al. (2011). The ShakeOut Scenario: A hypothetical Mw7.8 earthquake
on the southern San Andreas Fault. Earthquake Spectra, Vol. 27, No.
2, pp. 239-261.Current and Future Work #S.
Swensen21AcknowledgementsThis research is funded by the National
Science Foundation under a grant from the Network for Earthquake
Engineering Simulation (CMMI 1135029).
Additional support for testing was provided by the John A. Blume
Earthquake Engineering Center at Stanford University.
Input and guidance from an advisory committee (Greg Luth, David
Mar, Kelly Cobeen, Reynaud Serrette, John Osteraas, Rene Vignos,
Geoff Bomba, and Ali Roufegarinejad) has been critical in the
development of testing plans.
Support and encouragement from Ben Schmid, developer of the
MAXI-SYSTEM and the enhanced fasteners tested is thankfully
acknowledged.
#