Engineering Research Center Integrated Analytical and Experimental Approach to Precast Concrete Diaphragm Research José I. Restrepo, UCSD Robert Fleischman,

EngineeringResearchCenter

Integrated Analytical and Experimental Approach to Precast

Concrete Diaphragm ResearchJosé I. Restrepo, UCSD

Robert Fleischman, UA

Clay Naito and Richard Sause, LU

S.K. Ghosh, S.K. Ghosh Associates, Inc.


PCI National ConventionOctober 2003

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



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



Producer Members

• Blakeslee Prestress, Inc.

• High Concrete Structures

• Precast/Prestressed Concrete Manufacturers

Association of California

• Spancrete, Inc.

• Tindall-Virginia



Research Objective Develop a Seismic Design Methodology for Precast

Diaphragms



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.GhoshDSDM Task Group Chair

President, S. K. Ghosh Associates

R. BeckerVice President

Spancrete Industries, Inc.

N. ClelandPresident

Blue Ridge Design, Inc.

Tom D’ArcyPresident

Consulting Engineers Group

N. HawkinsProfessor Emeritus

Univ. of Illinois

Paul JohalResearch Director

PCI

Joe MaffeiEngineering ConsultantRutherford & Chekene

Engineers

Susie NakakiPresident

The Nakaki Bashaw Group, Inc.



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

Diaphragm Classification (DC)

Designation Seismic Zones

Ordinary OD A,B,C

Intermediate ID B,C,D,E

Special SD D,E,F



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



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



Research Required to meet Design Objectives

• 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

Research to determine the likely:



Research Challenge

• 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)

Challenges exist in determining these values:

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.



Research Approach:Integrated Analysis and Experimentation

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Side Walls

Load Cell

Floor Diaphragms

Shake Table

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Steel Base withCantilever Outriggers

6 ft – 6 in

UA Analyses link UCSD structure tests with LU

detail tests.

Research Program at UCSD

• University of California, San Diego Investigators

• Sponsors– PCI

– PCMAC

– Spancrete

J. Restrepo, Ph.D.

PCI Committee DaysApril 2003



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 System’s response



Experimental Program at UC San Diego

• Three-story one-quarter scale building with a 3:1 aspect diaphragm




• 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




• 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 system’s

dynamic response




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Shake Table

ReactionWall

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Building Elevation and Quasi-static Testing of Diaphragm




• 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



Analytical Program at the University of Arizona

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

Robert B. FleischmanRobert B. Fleischman, Ph.D., Ph.D.University of Arizona



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

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.



Research Program at Lehigh University

• Experimental Investigation of Precast Units/Joint Reinforcement Details

• Detailed Finite Element Investigation of Joint Connection Performance

• Simplified Analytical Models



Experimental Investigation of Precast Units/Joint Reinforcement Details



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



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)

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Integration and Flow of Research Activities

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2

3

2a

3a

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Proposed Research ScheduleTASK PROJECT YEAR 1 TEAM 1 2 3 4 5 6 7 8 9 10 11 12

0 NSF GOALI Program funding acquired PT

1 Finalize IAP PT, PCI

2 Review design code, state of practice PT, DSDM

3 Set agenda - distribute to IAP PT

RM1 First Research Meeting PT,IAP OC1-34 Refine Analytical Models UA,UCSD

5 EQ simulations on Prototype Structures UA, UCSD OC46 LU Simple Panel-Panel Connection Tests LU Setup OC57 Plan UCSD Shake Table Program UCSD,DSDM Planning8 Dynamic analysis of shake table structures UCSD

9 FE analyses of Shake Table diaphragms UA

10 Finalize UCSD Shake Table Program UCSD

RM2 Second Research Meeting PT,IAP

11 Produce Interim Report PT, DSDM prepare present write approve12 Produce specimens for Shake Table tests PR

13 FE (diaphragm) analyses of prototype floor plans UA toppedTASK PROJECT YEAR 2 TEAM 1 2 3 4 5 6 7 8 9 10 11 12

13 FE (diaphragm) analyses of prototype floor plans UA

14 Build Shake Table Specimens UCSD

15 Quasi-static Tests on Diaphragm UCSD

16 Shake Table Testing UCSD

RM3 Third Research Meeting PT,IAP

17 Compare shake table results with FE analyses UA, UCSD

18 Diaphragm Panel-Panel Connection Tests LU

19 Finalize loading patterns UA, LU

RM4 Fourth Research Meeting PT,IAP

20 Multiple Connection Panel-Panel Tests LU

TASK PROJECT YEAR 3 TEAM 1 2 3 4 5 6 7 8 9 10 11 1220 Multiple Connection Panel-Panel Tests, cont. LU

21 Models and Analysis for untopped UA untopped (con't)22 Determine Quantification metrics, testing protocol PT, DSDM

RM5 Fifth Research Meeting PT,IAP

23 Develop Design Methodology24 3D FE out of plane/anchorage UA, LU

RM6 Sixth Research Meeting PT,IAP

25 Final ReportKEY: Experiments in bold; Analyses in Italics PT = project team (entire); IAP = Industry Advisory Panel (includes Task Group); DSDM =Task Group; PR = producers;

PCI = Precast/Prestressed Concrete Institute; LU = Lehigh Univ., UCSD = Univ. Cal. San Diego, UA = Univ. Arizona

topped (con't) untopped

Planning



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.

Documents

Engineering Research Center Integrated Analytical and Experimental Approach to Precast Concrete Diaphragm Research José I. Restrepo, UCSD Robert Fleischman,