THE CFS-NEES EFFORT: ADVANCING COLD-FORMED STEEL EARTHQUAKE ENGINEERING

Benjamin Schafer, Johns Hopkins UniversityBonnie Manley, American Iron and Steel Institute

Cheng Yu, University of North Texas Colin Rogers, McGill University

Cris Moen, Virginia Tech David Padilla-Llano, Virginia Tech

Deniz Ayhan, Johns Hopkins UniversityJiazhen Leng, Johns Hopkins University

Kara Peterman, Johns Hopkins UniversityMatt Eatherton, Virginia Tech

Matt Stehman, Johns Hopkins UniversityNaru Nakata, Johns Hopkins University

Peng Liu, Johns Hopkins UniversityRob Madsen, Devco Engineering

Steve Buonopane, Bucknell University

CFS-NEES Project TeamBen Schafer PINaru Nakata coPISteve Buonopane coPIRob Madsen Sr. PersonnelGraduate StudentsKara Peterman Exp. GRAJiazhen Leng Comp. GRADeniz Ayhan JHU Vis. Stud. Peng Liu JHU Vis. Stud. Cristina Ganea JHU Vis. ScholarUndergraduate and HS ResearchersTara Early BU UndergradXiaolong Li BU UndergradJohn Puleo BU UndergradThet Hein Tun BU UndergradKelly Burkhart BU UndergradLaura Rendos CWU REU UndergradMolly van Doren JHU UndergradDarren Saulsbury, Jr. JHU HS Res.

International and Domestic CollaboratorsColin Rogers McGill Collab.Cheng Yu UNT Collab.Cris Moen V. TechMatt Eatherton V. Tech

Industry CoordinationBonnie Manley AISI Industry LiaisonDon Allen DSi EngineeringRahim Zadeh SSMAGeorge Frater CSCC (Canada)Rick Haws IAB Member Tom Castle IAB Member Kelly Cobeen IAB MemberRandy Daudet IAB MemberSteve Tipping IAB MemberJay Parr IAB MemberRenato Camporese IAB Member

Ledger framing detail (floors hung off of studs)

• Sited in Orange County, CA• 50 ft x 23 ft footprint

with 9 ft stories• Cold-formed steel for gravity• Floors are ledger-framed• Cold-formed steel with

OSB sheathing for lateral • Professionally designed by

Devco Engineering Inc. (“state of the practice” standard)

• Tested on twin shake tables at UB SEESL lab

• www.ce.jhu.edu/cfsnees for plans, calcs, narrative, etc.

CFS-NEES Archetype Building

Schafer, Manley, Madsen

CFS Member Characterization - Axial

Schafer, Moen, Padilla-Llano, Eatherton

CFS Member Characterization - Flexural

Schafer, Moen, Padilla-Llano, Ayhan, Eatherton

Shear wall characterization

varied seam location

with gypsum on back

without gypsum

7’up8’up

1’over 2’over

4.5’up

Unique details: ledger, panel seams, non-structural contributions

Schafer, Yu, Leng, Peterman

Shear wall characterization (cont.)

Schafer, Yu, Leng, Peterman

Pinching04

equivalent truss

OpenSeesBuilding models

rotational spring (5)vertical spring

at hold-down (3)

fixed (1-6)

fixed (1,2,3,4,6) at shear anchor

fastener element (1,3)

rigid diaphragm (2)

diaphragm master node at center of sheathing

nodebeam-column

element

1

23

fixed (1,2,4,6)

OpenSees model withnonlinear “fasteners” and

rigid sheathing

Generalized fastener-based shear wall s

Schafer, Moen, Padilla-Llano, Peterman, Eatherton, Buonopane

Model-based path for shear walls

Schafer, Buonopane

fastener-based model

validation

model reduction

equivalent trussOpenSeesBuilding models

Full Scale Building Testing

Structural Test Full System Test

Complete details provided in Dr. Peterman’s talk. Full scale testing was a great deal of the focus for the effort.

Schafer, Manley, Peterman, Stehman, Nakata, Madsen

OpenSees Building Modeling

A1-3D-RDb A1-3D-RDa

A1-3D-SDa

Modeling considerations1. Shear walls2. Hold downs3. Shear anchors4. Diaphragms5. Exterior gravity walls6. Mass distribution7. Interior walls and stairs

Schafer, Leng, Buonopane

Exploring impact of model fidelity

ExperimentT1 = 0.32 slong direction white noise 0.1 PGA

A1-3D-RDbT1 = 0.48 sT2 = 0.45 sT3 = 0.38 s

A1-3D-RDaT1 = 0.38 s T2 = 0.37 sT3 = 0.32 s

A1-3D-SDa T1 = 0.32 s T2 = 0.29 sT3 = 0.23 s

Schafer, Leng, Buonopane

Companion steel sheet shear wall efforts

Schafer, Rogers

other archetypes

….

IDA and “P695 analysis”

Conclusions• CFS-NEES is providing a multi-prong effort to advance the seismic

design of cold-formed steel framing applications• Significant progress has been made in experimental characterization

at a variety of levels: fastener, member, assemblage, full-scale; and in characterization methods (predicting response) that have potential applications in design

• Full-scale testing provides first look at the full system effect for cold-formed steel frame construction and it is significant across the board, new approaches are needed

• Current design results in excellent performance, far better than code minimums, but not necessarily for the right reasons (whole structure participates, “R” derived greatly from overstrength, our current ELF model is wholly inaccurate)

• Knowledge and tools developed along the CFS-NEES path provide an on-ramp to the highway of seismic performance-based design for cold-formed steel structures and the formal evaluation of seismic response modification coefficients, but significant work remains

S U P P L E M E N T A L

Also see www.ce.jhu.edu/cfsnees

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sGeorge E. Brown, Jr. Network for Earthquake Engineering Simulation

ContactDr. Benjamin W. Schafer (PI)

Professor and ChairDept. of Civil EngineeringJohns Hopkins UniversityPhone: (410) 516-6265

Email: schafer@jhu.edu

Publications

Journal PapersJournal articles based on the CFS-NEES work are in production, latest findings are transmitted in Research Reports andConference Proceedings as close to the time the work is completed as possible and listed below.

CFS-NEES Research ReportsC.A. Ganea, B.W. Schafer (2013). "Challenges with Analysis-Based Design for Light Steel Framing: Modeling the CFS-NEES Building in Commercial Structural Analysis Software." Research Report, CFS-NEES, RR05, (forthcoming as of July2013).

K.D. Peterman, B.W. Schafer (2013). "Hysteretic shear response of fasteners connecting sheathing to cold-formed steelstuds" Research Report, CFS-NEES, RR04, January 2013, access at www.ce.jhu.edu/cfsnees

P. Liu, K.D. Peterman, B.W. Schafer (2012). "Test Report on Cold-Formed Steel Shear Walls" Research Report, CFS-NEES, RR03, June 2012, access at www.ce.jhu.edu/cfsnees

D. Ayhan and B.W. Schafer (2012). "Moment-Rotation Characterization of Cold-Formed Steel Beams" Research Report,CFS-NEES, RR02, April 2012, access at www.ce.jhu.edu/cfsnees.

R.L. Madsen, N. Nakata, B.W. Schafer (2011) "CFS-NEES Building Structural Design Narrative", Research Report, RR01,access at www.ce.jhu.edu/cfsness, October 2011, revised RR01b April 2012, revised RR01c May 2012 (Note, drawingsof the CFS-NEES building are contained in RR01, in addition the latest drawings are provided here for Phase 1 final v21June 2013, Phase 2 drawings still in draft as of July 2013)

Conference ProceedingsLeng, J., Schafer, B.W., Buonopane, S.G. (2013). "Modeling the seismic response of cold-formed steel framed buildings:model development for the CFS-NEES building." Proceedings of the Annual Stability Conference - Structural StabilityResearch Council, St. Louis, Missouri, April 16-20, 2013, 17pp.

Leng, J., Schafer, B.W., Buonopane, S.G. (2012). “Seismic Computational Analysis of CFS-NEES Building.” Proc. of the21st Int’l. Spec. Conf. on Cold-Formed Steel Structures, 24-25 October 2012, St. Louis, MO, 801-820.

Liu, P., Peterman, K.D., Yu, C., Schafer, B.W. (2012). “Characterization of cold-formed steel shear wall behavior undercyclic loading for the CFS-NEES building.” Proc. of the 21st Int’l. Spec. Conf. on Cold-Formed Steel Structures, 24-25October 2012, St. Louis, MO, 703-722.

D. Ayhan, B.W. Schafer (2012) "Moment-Rotation Characterization of Cold-Formed Steel Beams Depending on Cross-Section Slenderness" 15th World Conference on Earthquake Engineering, September 24-28, Lisbon, Portugal.

K.D. Peterman, N. Nakata, B.W. Schafer (2012) "Cyclic Behavior of Cold-Formed Steel Stud-to-Sheathing Connections"15th World Conference on Earthquake Engineering, September 24-28, Lisbon, Portugal.

P. Liu, K.D. Peterman, C. Yu, B.W. Schafer (2012) "Cold-formed steel shear walls in ledger-framed buildings", AnnualStability Conference, Structural Stabiltiy Research Council, April 2012, Grapevine, Texas.

D. Ayhan, B.W. Schafer (2012) "Characterization of moment-rotation response of cold-formed steel beams", AnnualStability Conference, Structural Stabiltiy Research Council, April 2012, Grapevine, Texas.

N. Nakata, B.W. Schafer, and R.L. Madsen (2012) "Seismic Design of Multi-Story Cold-Formed Steel Buildings: the CFS-NEES Archetype Building, 2012 Structures Congress, March 2012, Chicago, Illinois. 1507-1517.

D. Ayhan, B.W. Schafer (2012) "Impact of cross-section stability on cold-formed steel member stiffness and ductility",Annual Stability Conference, Structural Stabiltiy Research Council, May 10-14 2011, Pittsburgh, PA.

B.W. Schafer, N. Nakata, S.G. Buonopane, and R.L. Madsen (2011) "CFS-NEES: Advancing Cold-Formed SteelEarthquake Engineering, 2011 NSF CMMI Research and Innovation Conference, January 2011, Atlanta, Georgia.

PostersCFS-NEES: Advancing Cold-Formed Steel Earthquake Engineering, 2011 NSF CMMI Research and InnovationConference, January 2011, Atlanta, Georgia.

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Summary

Project Team

Schedule

Research Activities

Education & Outreach

Payload Opportunities

Publications

News & Events

Advisory Board

Sponsors

Branding

• Who: A collaborative research team centered at Johns Hopkins and lead by the PI: Ben Schafer, includes Naru Nakata, Steve Buonopane, Rob Madsen, collaborators, students, visiting scholars

• What: A $923,000 NSF-funded research effort, plus experimental funding enabled by the help of the American Iron and Steel Institute (AISI) and companion projects enabled by AISI. (Sponsors noted on next page)

• Where: Primarily at Johns Hopkins University, and utilizing the NEES testing facility in the SEESL lab at the University of Buffalo (UB)

• When: 2010-2014, Summer 2013 full-scale testing completed at UB

• Why: To enable engineers to practice seismic performance-based design of CFS buildings and to spur innovation in the seismic design of CFS systems

• How: Through a combined computational and experimental plan to develop new knowledge and analysis tools culminating in full-scale testing of a two-story cold-formed steel framed building.