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National Science Foundation Funded Research:NEESR-CR: Enabling Performance-Based Seismic

Design of Multi-Story Cold-Formed Steel Structures(CFS-NEES)

Introductory Presentationfor

I d t i l Ad i B dIndustrial Advisory Board26 January 2011

Thank you• Thank you

Rick HawsTom CastleKelly CobeenyRandy DaudetSteve TippingJay ParrRenato Camporese

for agreeing to participate on the Industrial Advisory Board for this project.

• I appreciate that your time is valuable, and I am honored by your willingness to spend some of that time assisting this project.

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• 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 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

• Where: Primarily at Johns Hopkins University, and utilizing the NEES testing facility at the University of Buffalo

• When: Over the next 3 years

• Why: To enable engineers to practice true 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.

CFS Seismic Design Today• We have neither the modeling capabilities, nor the

experimental understanding to complete a reliable seismic evaluation of CFS framed structures without relying on grossly conservative methodologiesrelying on grossly conservative methodologies.

• We cannot model fundamentally important phenomenon, such as local buckling in the analysis tools currently used for inelastic time history analysis

• We know precious little about CFS interactionssub-systems: stud-to-track, joist-to-rim,systems: gravity and shear walls floors roofs multi storysystems: gravity and shear walls, floors, roofs, multi-storycombined systems: LFRS vs. gravity vs. non-load bearingwhole buildingsThis project aims to set a new path for CFS seismic design

to address these issues and enable true performance-based seismic design

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Research Activities Summarycold-formed steelFrame FE

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

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minor axis bending (Mz/Mzy)

axia

l loa

d (P

/Py)

λcrλyλn

bucklingdirect strengthyieldingtests (Zhang 1989)

O

Cx x

z

z

1 12

2

θ

sub-systemtesting

high fidelityFE

full-scaleshaking

photo credit NEESWood

Research Activities Summary

CM(D)

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

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minor axis bending (Mz/Mzy)

axia

l loa

d (P

/Py)

λcrλyλn

bucklingdirect strengthyieldingtests (Zhang 1989)

O

Cx x

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z

1 12

2

θ

CM(A)

EXP

( )

FSB & IDAphoto credit NEESWood

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More detailed mapping of CFS-NEESComputational modeling

Experimental High fidelity High efficiencyComponent stud, joist, track AISI-COMP, (1) (1) CM(D)-1Sub-systems

t d t t k / j i t t i EXP 1 CM(A) 2 (1) CM(D) 2 stud-to-track / joist-to-rim EXP-1 CM(A)-2a, (1) CM(D)-2a stud-to-wall / joist-to-floor (1) CM(A)-2b, (1) CM(D)-2bSystems gravity walls (1) (1) (1) shear walls EXP-UNT, (2) CM(A)-3a (2) floor/roof diaphragms (3) CM(A)-3b CM(D)-4aSystem interactions gravity and shear walls EXP-2 CM(A)-3c CM(D)-4b walls with diaphragms EXP-3 CM(A)-3d CM(D)-4c multi-story walls EXP-McGill, (5) CM(A)-3e (5)M lti t B ildiMulti-story Building LFRS only FSB-4a FSB-7 FSB-6 All Structural FSB-4b FSB-7 FSB-6 Whole Building FSB-4c - FSB-6 Incremental Dynamic Analysis - - IDA(1) Prior research by PI Schafer et al. see proposal sections 6.1.1 and 6.2.1(2) Prior research by Int'l. Collaborator Rogers et al. see proposal section 6.1.2(3) Prior research in cold-formed steel literature see proposal section 6.1.3 (4) This note not utilized in this version of this table (see proposal for original version)(5) NSERC research of Rogers on multi-story shear walls

Research Activities Summary

CM(D)

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5

minor axis bending (Mz/Mzy)

axia

l loa

d (P

/Py)

λcrλyλn

bucklingdirect strengthyieldingtests (Zhang 1989)

O

Cx x

z

z

1 12

2

θ

CM(A)

EXP

( )

FSB & IDAphoto credit NEESWood

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Consider a typical EXP projectEvery EXP task conducted at JHU…• Literature review (CFS and Wood..)• Test objective/deliverables finalization• Pre-test computational modeling• Testing rig fixture development /

B d diti d t iliBoundary condition detailing• Ind. Advisory Board Coord. (milestone 1)• Loading protocol finalization• Testing matrix• Sensor plan• Shakedown testing (milestone 2)• NEES data coordination (RDV etc)• Full specimen pre-test characterization• Testing, data collection Planned Testing Areas

EXP

Testing, data collection• Ancillary material testing• Post-processing and data reduction• Post-test modeling assistance for data

reduction• Test report and NEES data (milestone 3)• Post-test computational modeling

expansion

Planned Testing AreasStud-to-trackJoist-to-rim

Gravity and shear wallsWalls with diaphragms

Consider a typical CM(D) project

CM(D)Typical CM(D) oriented task:• Modeling objective• Lit review & OpenSees, Commercial

software (STAAD?), SAPWood review• Determine benchmarks

Fi li bj ti d d li bl

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5

minor axis bending (Mz/Mzy)

axia

l loa

d (P

/Py)

λcrλyλn

bucklingdirect strengthyieldingtests (Zhang 1989)

O

Cx x

z

z

1 12

2

θ

• Finalize objective and deliverable• Objective, deliverable to IAB - milestone 1• Prototyping model • Model derivation• Model implementation/coding• Model verification problems – milestone 2• Model implementation into final

platform (likely OpenSees or ??)• Demonstration of developed element in Planned Models Demonstration of developed element in

larger framework problem• Reporting to NEESHub, uploading

element etc.• Reporting to IAB, demonstrate industry

impact of element• Final report on model/element – milestone 3

Planned ModelsCFS appropriate frame element

Connection elementWall model

Diaphragm modelEfficient IDA targeted

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more on full-scale testing

FSBat the Buffalo NEES facility

Multi-story CFS building(Architectural only)

l tielevation

explodedisometric

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Needed feedback on framing planThe following excerpted from Rob Madsen, Devco

Current design of the CFS-NEES archetype building utilizes roof joists and 2nd

level stud framing at 24” oc (alignment framed), but switches to 16” oc for the 2nd floor joists and 1st floor studs. The following concepts should be considered, along with any others, in making the final decision to stay with this hybrid spacing scenario, or just go with 16” oc throughouthybrid spacing scenario, or just go with 16 oc throughout.1. Due to the relatively minor roof loading, the roof joists and upper level studs can

easily meet strength and serviceability requirements at a 24” oc spacing.2. The higher spacing above the 2nd floor reduces the amount of steel and the number of

connections required, leading to a more economical structure.3. Due to the quantity and size of wall openings, there is very little true 2-story

alignment framing regardless of member spacing. Jamb studs and shearwall chords will align floor-floor regardless of the spacing of the typical stud framing.

4. Based on the modest loads in the 2nd flr studs, the notion is that the 2nd flr rim track ill di ib h l d h i h l d d h 1 t flwill distribute the loads to the more tightly spaced studs at the 1st flr.

5. Using the hybrid spacing will allow the testing to consider both 16” and 24” ocframing spacings for diaphragm and shearwalls.

6. Changing spacing will add some complexity to the behavior of the 2nd interface both for gravity and seismic loads. As discussed, that could be good or bad.

7. In our experience, this type of hybrid spacing is not common.8. Because we won’t be doing comprehensive gravity load testing, some of the potential

complexities of the system may not be revealed.

IAB Thoughts on Spacing/Building• PI Schafer – was inclIned to go for all 16 in. oc

until I listened to how Rob had come up with the design and the fact that true aligned framing will be rare with all the windows., in the end I am completely open to both alternatives, but we need to finalize this decision yesterday.

can, joists too. Framers prefer. Big market is multi-family, dorms, hotels.. Need to think more about this – pretend it is 2 story residential… 18 ft. everything works… Don’t worry about name – just go for shorter and interior bearing (Rob comment –the more residential we make it the more the non-

l ill d d ?)y y

IAB• Rick Haws – No comment.

• Tom Castle – 24 oc common in his experience (up to 5, 6 stories), increase t (2/3 labor anyway), maybe allow joists different spacing. No platform, all ledger-based…

• Kelly Cobeen – Studs too controlled by openings? Not enough to matter, use the same

structural will get watered down?)

• Jay Parr – DDG uses ledger framing, 16 or 24 but keep in-line (joists usually in-line). Almost all we do is residential – hotels, dorms, military… Loading of office building..

• Renato Camporese – Not a lot of load bearing stud design.. Elevation – openings are stacked? Mixed use – should the openings be stacked? Should we look at that..

p g g ,spacing.. Ben Question to removing windows.. (Formal seismic not done yet, we think windows will evolve) KC: Follow the calcs

• Randy Daudet – 24 oc, Q-Rob? A-Height restrictions at JHU testing limited joist depth, this lead to challenges with 12 in. joist unless doubled up. RD: Ledger framing – v – platform (Rob discussing floor to floor interface) Mixed use buildings…

• St Ti i l l k f

Other Participants• Jay Larson – intention primary gravity and

lateral on the exterior?

• Don Allen – baseline assumption about office –is the wrong track.. Midrise is residential – so we should think of having interior partition walls.

Note, the comments on this slide were recorded during the presentation

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IAB – We need you..

IO-2: Industrial Advisory Board (IAB)a. Establish IAB in coordination with AISI SDO/Bonnie Manleyb. Provide regular (quarterly? semi-annual?) reports to IABc. FSB - For full-scale building (FSB) testing at UB-NEES

i Feedback on building design with Madsen and CFS NEES team

From the CFS-NEES Work Plan

i. Feedback on building design with Madsen and CFS-NEES teamii. Feedback on state-of-the practice modelingiii. Assistance in appropriate suppliers, iv. Construction QA advicev. Feedback on motion protocols, sensor plans etc.

vi. Participation in tests as availabled. IDA - Coordination with incremental dynamic analysis (IDA) work

i. Feedback on state-of-the practice modelingii. FEMA-P695 Guidance and Feedbackiii. Coordination with larger AISI SDO effort on building archetypes

e. EXP – Coordination with Experimental testing at JHUe. EXP Coordination with Experimental testing at JHUi. Assistance in appropriate suppliersii. Feedback/assistance in initial testing protocols, details, test matrix

f. CM – Coordination with Computational Modeling teami. Feedback/assistance on objectives and deliverable for CM tasksii. Beta test developed CM tools in practice engineering setting (as appropriate)

Thank you.

Project TeamCFS-NEES Project TeamBen Schafer PINaru Nakata coPISteve Buonopane coPIRob Madsen Sr. PersonnelKara Peterman Exp. GRA

Industry CoordinationBonnie Manley AISI Industry LiaisonDon Allen SSMA, SFA, CFSEIGeorge Frater CSCC (Canada)Rick Haws IAB Member T C l IAB M b Jiazhen Leng Comp. GRA

Darren Saulsbury, Jr. HS Res.Andrew Faulkner JHU Undergrad

International and Domestic CollaboratorsDeniz Ayhan JHU Vis. Stud. Qiu Guozhi JHU Vis. ScholarPeng Liu JHU Vis. Stud. Colin Rogers McGill Collab.Cheng Yu UNT Collab.Cris Moen V Tech

Tom Castle IAB Member Kelly Cobeen IAB MemberRandy Daudet IAB MemberSteve Tipping IAB MemberJay Parr IAB MemberRenato Camporese IAB Member

Cris Moen V. TechMatt Eatherton V. Tech