Integrated Analytical and Experimental Approach to Precast Concrete Diaphragm Research

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Integrated Analytical and Experimental Approach
to Precast Concrete Diaphragm Research

• José I. Restrepo, UCSD
• Robert Fleischman, UA
• Clay Naito and Richard Sause, LU
• S.K. Ghosh, S.K. Ghosh Associates, Inc.

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Background

• Arizona-Lehigh-UCSD Consortium awarded grant from
  PCI for 200,000 in December 2002.
• Diaphragm Seismic Design Methodology (DSDM) Task
  Group Established
• Producer Member Donations Identified (91,000)
• Arizona-Lehigh-UCSD Consortium awarded GOALI
  grant from NSF for 467,406 in August 2003
• Official Start Date - October 2003 3 year
  duration

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DSDM Consortium
PCI, IAP
DSDM Task Group
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Producer Members

• Blakeslee Prestress, Inc.
• High Concrete Structures
• Precast/Prestressed Concrete Manufacturers
  Association of California
• Spancrete, Inc.
• Tindall-Virginia

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Research Objective

• Develop a Seismic Design Methodology for Precast
  Diaphragms

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DSDM Task Group

• Help to guide the physical scope
• Selection of prototype structures in terms of
  lateral system types, story height, and floor
  plan
• Involvement with transformation of research
  results into an appropriate design methodology

S.K.Ghosh DSDM Task Group Chair President, S. K.
Ghosh Associates
R. Becker Vice President Spancrete Industries,
Inc.
N. Cleland President Blue Ridge Design, Inc.
Tom DArcy President Consulting Engineers Group
N. Hawkins Professor Emeritus Univ. of Illinois
Paul Johal Research Director PCI
Joe Maffei Engineering Consultant Rutherford
Chekene Engineers
Susie Nakaki President The Nakaki Bashaw Group,
Inc.
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DSDM Task Group Activities

• Review and approve research program
• Evaluate existing code
• Gain consensus on design approach

• Determine physical scope
• initial set of reinforcement details existing,
  promising
• prototype structures systems and seismic zones
• representative floor plans layout, construction
• Design of prototype structures

• Periodically evaluate research direction
• Transfer of research into practice and codes

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Research Scope

• To be jointly determined by DSDM Task Group and
  University Consortium, based on need and
  resources

• Topped and Pretopped Diaphragms
• Hollow Core and Double Tees Precast Units
• Prototypes Structural System, Seismic Zone
• Representative Floor Plans
• Existing and Promising Reinforcement Details
• Panel Joints, Beam Interfaces, Wall/Frame
  Anchorages, Topping/Precast Unit Bond

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Design Objectives of Methodology

• Seismic Design Methodology for Precast Concrete
  Diaphragms must include

• Diaphragm Design Force Patterns
• Diaphragm Internal Force Calculations
• Diaphragm Stiffness Calculations
• Diaphragm Reinforcement Capacities
• Diaphragm Flexibility Limits
• Diaphragm Structural Integrity Details

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Research Required to meet Design Objectives
Research to determine the likely

• force demands on the overall diaphragm
• internal force distribution for calculating
  reinforcement
• force combinations at sections
• axial-flexure interaction in collectors
• deformation patterns and local ductility demands
• diaphragm-induced drift demands

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Research Challenge
Challenges exist in determining these values

• Inertial force demands depend on overall
  structural dynamics including diaphragm
  flexibility effects extreme instantaneous load
  events are likely (Design Force Pattern)
• Load paths are dependent on details and floor
  plan layout (Internal Force Calculation).
• Gravity system drifts are related to floor span,
  lateral system type and diaphragm design strength
  (Flexibility Limits).
• Given extreme load events, ductility demands are
  difficult to avoid in severe earthquake
  (Structural Integrity Details)

These issues are the result of interrelated
behaviors that encompass response at the detail,
joint, diaphragm and structural level. Uncoupling
these responses or relying on idealized
(analytical) boundary conditions to extrapolate
response will likely produce incorrect
conclusions.
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Research Approach
Integrated Analysis and Experimentation
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Research Program at UCSD

• University of California, San Diego Investigators
• Sponsors
• PCI
• PCMAC
• Spancrete

J. Restrepo, Ph.D.
PCI Committee Days April 2003
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Scope of Project at UC San Diego

• Analytical work for determining floor
  acceleration demands for the design of buildings
  with rigid diaphragms
• Shake table experimental work to assess the
  Systems response

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Experimental Program at UC San Diego

• Three-story one-quarter scale building with a 31
  aspect diaphragm

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Experimental Program at UC San Diego

• Each level will incorporate a representative type
  of precast concrete diaphragm and typical
  connection details used in practice
• Two floors with topped diaphragms
• One floor with an untopped diaphragm
• Diaphragm reinforcement design TBD
• Current code
• New methodology

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Experimental Program at UC San Diego

• Building response characterization
• Initial simple and refined non-linear
  time-history analyses to be conducted by UCSD and
  UA
• Testing Phase
• Quasi-static testing to determine the diaphragm
  flexibility at each level
• Dynamic testing to determine the systems
  dynamic response

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Experimental Program at UC San Diego
Building Elevation and Quasi-static Testing of
Diaphragm
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Experimental Program at UC San Diego

• Shake-table dynamic testing
• To follow the test protocol successfully used for
  the testing of the Caltech-Curee Woodframe house
• Ensemble of time-histories
• Pulse-loading
• Band-limited white noise
• Historic ground motions, including a near-fault
  record

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Analytical Program at the University of Arizona
Robert B. Fleischman, Ph.D. University of Arizona

• Analysis will link structure/diaphragm level
  experiments at UCSD with joint/reinforcing detail
  level experiments at Lehigh.

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Analytical Program at the University of Arizona

• Two-stage approach adopted in previous research
  will be extended

• Nonlinear static (pushover) analyses of
  individual diaphragms
• diaphragm models will be based on data from
  Lehigh baseline tests and existing data
• Nonlinear dynamic analysis of structures under
  earthquake
• models of prototype structures will be based on
  diaphragm analyses and UCSD quasi-static tests
• Together, the two stages, suggest the Lehigh MCD
  tests
• structure analyses provide demand levels
• diaphragm analyses provide boundary conditions
  and critical regions
• analyses verified or calibrated by shake table
  tests

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Research Program at Lehigh University

• Lehigh University Investigators
• Sponsors
• PCI
• ATLSS/PITA
• High Concrete Industries
• Blakeslee Prestress Inc.
• Tindall-Virginia

C. Naito, Ph.D., P.E.
R. Sause, Ph.D., P.E.
Engineering Research Center
PCI Committee Days April 2003
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Research Program at Lehigh University

• Experimental Investigation of Precast Units/Joint
  Reinforcement Details
• Detailed Finite Element Investigation of Joint
  Connection Performance
• Simplified Analytical Models

Engineering Research Center
PCI Committee Days April 2003
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Experimental Investigation of Precast Units/Joint
Reinforcement Details
Engineering Research Center
PCI Committee Days April 2003
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Multi-Component Diaphragm (MCD)Test Fixture

• Performance of the connected precast units
  subjected to a combination of shear, axial load,
  and flexure across key portions of joints between
  precast units

Engineering Research Center
PCI Committee Days April 2003
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Experimental Program at Lehigh University

• Full-scale Components (Full-width 10ft.)
• Double Tee and Hollow Core Panels
• Topped and Untopped
• Quasi-Static Loading
• Baseline Tests
• Pure shear / axial force
• Monotonic and Cyclic
• Single and multiple connector
• Diaphragm Panel-Panel Tests
• High shear and flexure regions (predetermined
  cyclic)
• Multiple Panel Tests
• High shear, tension, and flexure loading (from
  analysis)

1-1
Engineering Research Center
PCI Committee Days April 2003
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Experimental Program at Lehigh University

• Connection details to be determined through DSDM
  Task Group
• Up to 16 test specimens
• Multiple tests per panel

2-2
3-3
Engineering Research Center
PCI Committee Days April 2003
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Integration and Flow of Research Activities
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Proposed Research Schedule
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We are grateful to PCI, producer members, and the
industry participants for their strong support of
this research. We look forward to a fruitful
research project culminating in a new seismic
design methodology for precast diaphragms.