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![Page 1: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/1.jpg)
EngineeringResearchCenter
Development of a Precast Floor Diaphragm Seismic Design
Methodology (DSDM)Robert Fleischman, UA
Clay Naito and Richard Sause, LU
Jose Restrepo and Andre Filiatrault, UCSD
S.K. Ghosh, S.K. Ghosh Associates, Inc.
![Page 2: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/2.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
DSDM Consortium
P ro d uce r M em b e rs
U n ive rs ity o f C a lifo rn iaS a n D ie go
Jo se R e stre po , P IA n d re F ilia tra u lt, C o -P I
P ro d uce r M em b e rs
L e h igh U n ive rs ityC la y N a ito , P I
R ich ard S au se , C o -P I
In d u s try A d viso ry P a n e l
In d u stry L ia isonS . K . G h osh , C o -P I
U n ive rs ity o f A rizo naR o b e rt F le isch m anC o n so rtium L ea d er
DSDM Task Group
PCI, IAP
![Page 3: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/3.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Status• PCI R&D providing $200,000 in funds for
project research activities.
• Proposal submitted to NSF GOALI Program February 7, 2003.
• Awaiting outcome of the review process (NSF Panel met August 4 2003).
• Project Original Start Date August 2003
• Initial DSDM Research Meeting.
![Page 4: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/4.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
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Side Walls
Load Cell
Floor Diaphragms
Shake Table
ReactionWall
Steel Base withCantilever Outriggers
6 ft – 6 in
Proposed Research Approach:Integrated Analysis and Experimentation
![Page 5: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/5.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Integration and Flow of Research Activities
1
2
3
2a
3a
4
Diaphragm Characteristic
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting Objectives
1. Establish consensus on a design philosophy to guide research
DSDM Research #1
2. Establish guidelines for the physical scope of the research
3. Review and comment on plans for Lehigh Phase I test program
Fleischman/Restrepo
Sause
Naito
NOTE: Design approach will impact project direction; physical scope will define project outcome
![Page 7: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/7.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting Objectives 1. Establish consensus on a design
philosophy to guide research
DSDM Research #1
• Applicability of Design/Analysis Methods: Beam Analogy, Strut & Tie; Stringer and Panel (Restrepo)
• Hollow Core details, emerging techniques and emphasis (Restrepo)• Discuss importance of lateral system layout (Restrepo)
• Role of Elastic Diaphragm Design and Need for Detailing for Ductility in High, Moderate, Low Seismic Zones (Fleischman)
• Role of Web Reinforcement: compliance vs. ductility (Fleischman)• Applicability of construction methods: composite, non-composite,
pretopped (Fleischman)
![Page 8: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/8.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
1. Role of Elastic Diaphragm Design and Need for Detailing for Ductility in High, Moderate, Low Seismic Zones
DSDM Research Meeting #1
Researcher Nakaki Rodriguez/ Restrepo
Farrow/Fleischman/Sauce
NEHRP Appdx.
Design Force Approach
Design to LFRS Ultimate
Use R Factor on 1st mode only
is function of diaphragm flexibility
Higher factor for untopped
Design Force = 2.8 i = ~2 = 1.0-3.0
Nakaki: Structure overstrength factor to bring diaphragm design to the ultimate state (Squat walls use R=1).
Rod/Rest: Floor magnification factor based on vertical location of the floor and influence of higher modes.
Far/Flei/Sause: Overstrength factor based on diaphragm flexibility (Alternative for elastic design)
![Page 9: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/9.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting1. Role of Elastic Diaphragm Design and Need for Detailing
for Ductility in High, Moderate, Low Seismic Zones
DSDM Research #1
Nakaki: Identifies important inconsistencies including designing diaphragm ultimate state to lateral system “first yield”. However, other factors exist in diaphragm overload (See Rodriguez et al; Fleischman et al).
COMMENTS:
CONCLUSIONS:
• Calibrate through research.
• Tradeoff between and ductility demand (and drift demands) .
![Page 10: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/10.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting1. Role of Elastic Diaphragm Design and Need for Detailing
for Ductility in High, Moderate, Low Seismic Zones
DSDM Research #1
ISSUES: • Is the desired approach?
– Design for a specified force level and accept ductility demands, or– Design for a specified ductility demand (including elastic) and accept force level
• The proper approach likely depends on:– Diaphragm span– Lateral system– Seismic Zone
• What is acceptable damage?
• What is the target seismic level?
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingOne Possible Approach: Different Force levels depending
on zone, span and details:
DSDM Research #1
Diaphragm Classification (DC)
Designation Seismic Zones
Ordinary OD A,B,C
Intermediate ID B,C,D,E
Special SD D,E,F
Classify Precast Diaphragms in terms of detailing requirements.
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingDifferent Force level depending on zone, span & details:
DSDM Research #1
Seismic Design Category
Diaphragm Span
A B C D E F
Lcl<LfdDC OD OD OD ID ID SD ID SD SD
px * * e * e
Lcl>LfdDC OD ID OD ID ID SD SD
px e * e * e
Define applicability of diaphragms for different zones, forces and spans.
![Page 13: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/13.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingDifferent Force level depending on zone, span & details:
DSDM Research #1
Classification OD ID SD
Reinforcement detailing detailing detailing
Collector 0.75 0.75 regular 0.6 special
Chord 0.9 0.9 regular 0.9 special
Web Shear 0.75 0.75 0.6
Tension Type A Type B Type C
Specify strength reduction and detailing requirements for each classification
![Page 14: Engineering Research Center Development of a Precast Floor Diaphragm Seismic Design Methodology (DSDM) Robert Fleischman, UA Clay Naito and Richard Sause,](https://reader035.fdocuments.in/reader035/viewer/2022070418/5697bf8e1a28abf838c8ca7c/html5/thumbnails/14.jpg)
EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting Objectives
2. Role of Web Reinforcement: compliance vs. ductility
DSDM Research #1
Researcher Nakaki Farrow/ Fleischman
Diaphragm Web Reinforcement Approach
The diaphragm is designed against My where
yield can occur in the chord or at the extreme web reinforcement. Two detailing approaches are proposed: tension resistant connector details and tension compliant web details
Capacity design for web reinforcement based on comparing dynamic demands with pushover results
ReinforcementCalculation
Strength Criterion:Based on strain compatibility formulation in which curvature, and hence moment, is controlled by the limiting elastic deflection of the most extreme web connection or the chord steelStiffness Criterion:Uses an effective stiffness factor based on flexure and applies it equally to the shear resistance (basis of the NEHRP force amplification factor bd [1+0.4(Leff/bd)
2]/12hs)
v= 0.6
b= 0.9
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting2. Role of Web Reinforcement: compliance vs. ductility
DSDM Research #1
Nakaki: Method shows efficacy of tension compliance; may be overly conservative for tension resistant due to assumed debonded length
COMMENTS:
ISSUES: • Should floors be designed as deep sections (to over 50’) with flexural strength and stiffness
ONLY provided by boundary elements?
• Can a viable shear connection be created instead that is both tension strong/stiff and tension ductile? (distinguish between 3 types)
Fleischman: Capacity design (in shear) does not directly address tension demand.
• What are the serviceability issues involved?
• Do altogether different solutions exist?
• How severe is the loss of a portion of the web reinforcement?
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting
2. Role of Web Reinforcement: compliance vs. ductility
DSDM Research #1
CONCLUSION:
• This is a key issue, maybe hold off discussion until after second part of presentation.
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting Objectives
3. Applicability of construction methods
DSDM Research #1
QUESTION: What are the industry’s desires in terms of:
• Extent of applicability of untopped diaphragms
• Interest in topped noncomposite• Geographic Focus: emphasis on high seismic?
• Solutions for Hollow Core vs. Double Tees
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting Objectives DSDM Research #1
• Structural System– Type– Layout
2. Establish guidelines for the physical scope of the research
• Diaphragm – Construction– Plan
• Details
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingDSDM Research #1
A. Structural System• Lateral System
– Wall systems– Frame systems– Dual systems
• Profiles– Low rise– Mid Rise– High rise
• Layout– Perimeter– Interior– Mixed
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingDSDM Research #1
B. Diaphragm• Construction
– Topped Noncomposite– Topped Composite– Untopped
• Precast Floor System– Double Tee– Hollow Core
• Construction Practice– Internal Walls– Spandrel Details– Tee Beam Details, etc.
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingDSDM Research #1
B. Diaphragm (Layout)• Interior Beams
• Interior Cavity
• Irregular Floor Plans
• Continuous Spans
• Long vs. Squat
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
MeetingDSDM Research #1
C. Diaphragm Details• Typical Construction
• Proprietary Details
• Emerging Details
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EngineeringResearchCenter
DSDM Research Meeting #1August 7, 2003
Meeting Objectives DSDM Research #1
Resources• Existing Example Structures
– Nakaki EERI: 10 story frame; 3 story wall– Englekirk/Nakaki: Typical Northridge Parking Garage– Cleland – Design Examples from Seismic Committee– PCI Handbook?
ISSUE: University Researchers can follow the code in creating design but will have difficulty in producing designs that possess the typical “state-of-practice” of construction in various regions of the country
SOLUTION: DSDM produce a set of prototype structures to guide the research
NOTE: Certain studies (effect of # of stories) can be performed using approximate designs.