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

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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

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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

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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.

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