ComparativeShearWallDesign - Kurc

8/8/2019 ComparativeShearWallDesign - Kurc

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Outline

Introduction

Buildings utilized in the Case Studies

Design of High Ductility Shear Walls

Design of Normal Ductility Shear Walls

Conclusions


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Introduction

New version of Turkish Earthquake Code (TDY-

2007) was released in 2007 Capacity design approach for the shear walls was

introduced for the first time

Objections from practicing engineers, especiallyfrom the ones who build shear wall dominatedbuildings (utilizing tunnel forms)

Modifications were made to the code and first

Annex was released on May 2007 New version of the code still does not satisfy the

design engineers and academicians.


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Case Study Architectural Plan

25

655

10

250

20

250

10

655

25

10

90

25

410

10

270

5

120

20

120

10

265

10

410

25

90

10

25

395

10

250

10

520

10

250

10

395

25

10

90

410

10

265

10

120

20

120

10

265

10

410

90

10

25

655

25

335

160

25

25

25

25 505 10 310 10 110 10 220 20 220 10 110 10

25 25 10 10 10 400 25


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Case StudyBuilding Models

5 Storey Building 12 Storey Building

a) Shear Wall only

b) Dual System

a) Shear Wall only

b) Dual System

1st and 3rd Degree Earthquake Regions

Designed according to ACI 318-08 & TDY-2007


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Case StudyFraming & Shear Wall Dimensions

12 Storey Building5 Storey Building

3,75m

4,4m or 6,24 m

3,75m

4,4m

5,2m


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Shear Wall Design

Part I

High Ductility Shear Walls TDY 2007Special Shear Walls IBC 2005 / ACI 318-08


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Design for FlexureDesign Moments

Hw

Lw

HcrPlastic Hinge

Region

DesignMomentEnvelope

Moment Diagram

Obtained fromAnalysis

TDY-2007

ACI 318-08


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Detailing - Boundary Regions

TDY-2007 ACI 318-08

c-0.1lw

or c/20.2lw

Length (lu):

Minimum LongitudinalReinforcement Ratio: 0.002Acv up to Hcr0.001Acv elsewhere

No specific rule

Transverse Reinforcement

Amount:

ytk

ckcsh

f

fbsA

= 05.0

ytk

ckcsh

f

fbsA

= 09.0

Boundary Region

Boundary Region Boundary Region


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Boundary Region Length - ACI

c lu=c-0.1lwor c/2

lu= 90 cm (ACI)

lu= 75 cm (TDY)


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Boundary RegionResults

Boundary RegionLength

Boundary RegionSpecial Transverse

Reinforcement

Length TDY-2007 ACI 318-08TDY-2007

(mm)

ACI 318-08

(mm)

5 StoreyShear

Wall

3.75m 75 cm 90 cm 8/100 12/100

6.24m 125 cm 150 cm 8/100 12/100

5 StoreyDual

System

3.75m 75 cm 80 cm 8/100 -

4.40m 90 cm 65 cm 8/100 -


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d

td

tp

ve VM

M

V )(

)(

.=

Capacity Design ApproachDesign for Shear TDY 2007

Mp

At every wall section

Dynamic Magnification Factor

Flexural Over-strength Factor

Mp = 1.25 Mr

Mr


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Dynamic Magnification Factor

TDY 2007 1st Version

v = 1.5 All Systems

TDY, Annex I, May 2007

v = 1.0 Special Shear Wall Systems

v = 1.5 Dual System


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Shear DesignTDY-2007

Storey Md

Mrt

Vd

Ve

Ve/V

d

12 StoreyShear Walls Only (5.2 m)

1st 28,577 31,643 1,126 1,558 1.38

12 StoreyDual System (5.2 m)

1st 7,450 11,039 880 2,444 2.78

12 StoreyShear Walls Only (5.2 m)

6th 18,110 20,045 856 1,201 1.29

12 StoreyDual System (5.2 m)

6th 4,967 8,283 395 1,237 3.13

All units are in kN and m


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Capacity Design ApproachDesign for Shear T.Paulay*

Flexural Over-strength Factor Wall Base

td

tp

wo

M

M

)(

)(, =

Shear Force Wall Base

dwove VV = ,

* T. Paulay, M.J.N. Priestley, Seismic Design of Reinforced Concrete and Masonry Buildings, 1992


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Capacity Design ApproachDynamic Magnification Factor

Dynamic Magnification Factor, v Considers effects of higher order modes if the wall

forces are obtained by a STATIC ANALYSIS

T. Paulay proposes: up to 6 stories

otherwise

Wallace* proposes: v= 5/3 up to 10 stories

v= 4/3 otherwise

v = 1.0 if DYNAMIC ANALYSIS is performed*

109.0 nv +=

303.1 nv +=

*J. W. Wallace Evaluation of UBC-94 Provisions for Seismic Design of RC Structural Walls, Earthquake Spectra, May 1996


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Ve obtained from the capacity designapproach is the UPPERBOUND estimate

Strength reduction factors or materialfactors should be equal to UNITY

Shear Capacity, TDY-2007

Capacity Design ApproachShear Capacity - T.Paulay*

Ve obtained from the capacity designapproach is the UPPERBOUND estimate

Strength reduction factors or materialfactors should be equal to UNITY


cvctkyktr AffV 65.0+=

cvctdydtr AffV ..65.0. +=


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Ve obtained from the capacity design

approach is the UPPERBOUND estimate Strength reduction factors or material

factors should be equal to UNITY


Capacity Design ApproachShear Capacity - T.Paulay*

Ve obtained from the capacity design

approach is the UPPERBOUND estimate Strength reduction factors or material

factors should be equal to UNITY


cvctkyktr AffV 65.0+=

cvctkyktr AffV 43.087.0 +=


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Shear ForcesHeights above the Base, T. Paulay

Hw

Lw

Flexural

Overstrength is

Expected

Not a CriticalRegion

Shear Walls Only Dual System

Lw

0.33Hw

Ve

0.5Ve

Hw


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Shear Forces

Heights Above the Base, EC8


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Shear Force DistributionResults

* Base shear values were calculated according to TDY-2007


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Shear DesignACI 318-08

Does not have capacity designapproach

Analysis results are utilized during

the shear design Two additional rules:

ckTcvTu

fAV 66.0

ckcwu fAV 83.0

ATcv: Total shear wall area at each storey

Acw: Effective shear wall area

VTu: Total shear force at each storey

Vu: Shear force at each wall


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Shear Capacity - ACI 318-08

cvckyktr AffV ).17.0.( +=

ur VV

= 0.60 shear mode

= 0.75 bending mode


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Shear DesignACI 318-08

Wallace and Orakcal* presented that the

shear capacity of special shear wallsdesigned according to ACI 318-99 were notsufficient to carry shear forces obtainedfrom capacity design approach

Capacity design was not addressed in ACI,because shear distress of structural walls

has not been observed to produce lifesafety or collapse problems*

*J. W. Wallace and K. Orakcal, ACI 318-99 Provisions for Seismic Design of Structural Walls, ACI Structural Journal, July-August 2002


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Discussions

Magnified shearforces and moments

Different shear

force distribution fordifferent lateral loadcarrying system

Problems withoverdesigned walls

Foundation design?

Not observed tocause life safety orcollapse problems

Shear distressproblems

Ductility?

Encourages usingshear walls inbuildings

Capacity Design Not Capacity DesignOROR


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DiscussionsCapacity Design with TDY-2007

Minimum longitudinal reinforcement requirements

for boundary regions increases the flexural over-strength factor (Mpt/Md)

Problems with vcoefficient The effect of utilizing static and dynamic analysis

on the value vshould be identified

Should use at least 1.5 for shear wall systems

Current shear force distribution underestimatesthe shear forces at the upper levels

Design shear forces for large or over-designed

shear walls must be addressed The material factors (c, s) for capacity design

must be reconsidered.


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DiscussionsBoundary Regions with TDY-2007

Boundary region length, 0.2lw, is a rough

approximation, for some cases produces smallerlengths when compared with ACI 318-08

TDY-2007 requires almost two times less

transverse reinforcement at the boundary regionsthen ACI 318-08


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Shear Wall Design

Part II

Normal Ductility TDY 2007Ordinary Shear Walls IBC 2005


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Limitations

Lateral Load CarryingSystem

R B C D E F

Ordinary RC Walls 5 NL NL NP NP NP

Dual System with

Ordinary RC Walls

6 NL NL NP NP NP

Lateral Load Carrying System R

Shear Walls Only

Normal Ductility

4

Dual System

Normal Ductility

4

IBC 2005IBC 2005

TDYTDY--20072007

Permitted for allEarthquake Regions

Seismic Design Category(based on seismic hazard)

NL: Not LimitedNP: Not Permitted


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Flexural Design

ACI 318-08 No need for boundary regions

min = 0.0015

smax = 45 cm TDY-2007

Boundary Regions are formed as in High

Ductility System min = 0.0025

smax = 25 cm


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Flexural Design

Results

TDY-2007 ACI 318-08

Storey

Longitudinal +Boundary

Reinforcement(mm)

LongitudinalReinforcement

(mm)

1 2810/200+1222/200 3022/370

2 2810/200+1218/200 3016/370

3-12 4010/200+618/200 3010/370

WTDY = 2.00 * WACI


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Shear Design

ACI 318-08 Ve = Vd No need for boundary regions min = 0.0025 smax = min (45 cm, 3bw, lw/5)

TDY-2007 Ve = 2Vd Boundary Regions are formed as in High Ductility

Design min = 0.0025 smax = 25 cm


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Shear Capacity

Concrete

+=

w

uckc

l

dNdhfV

.4

...27,01

dh

lVM

hl

Nfl

fV

w

u

u

w

uckw

ckc ..

2

.2,01,0

05,02

+

+=

TDY-2007

cvckc AfV .15.0=

Shear Cracks at the centroid of the wall

Shear Cracks due to bending at lw/2

Vc = min (Vc1, Vc2)

ACI 318-08


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Shear Capacities - Concrete

VcTDY-2007

Vc1 Vc2Vc

ACI 318-08

12 StoreyShear Wall only5.2 m, 1. Level

1295,9 kN 1804,3 kN 452,9 kN 452,9 kN

5 StoreyDual System4.4 m, 1. Level

1079,9 kN 1040,2 kN 410,7 kN 410,7 kN

5 StoreyShear Walls only6.24 m, 3. Level

1555,1 kN 1416,8 kN 3258,3 kN 1416,8 kN


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Shear Design

Results 4.4m long wall

TDY-2007 ACI 318-08

Storey Vu (kN)Shear + Boundary

ReinforcementVu (kN)

ShearReinforcement

1 2563.26 10/100+8/100 1281.63 10/250

2 2293.08 10/250+8/100 1146.54 10/250

3 2215.82 10/250+8/200 1107.91 10/250

4-12 - 10/250+8/200 - 10/250

WTDY = 1.35 * WACI


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Shear Design

Results 5.2m long wall

TDY-2007 ACI 318-08

Storey Vu (kN)Shear +

BoundaryReinforcement

Vu (kN)Shear

Reinforcement

1 3442.52 12/200+8/100 1721.26 12/275

2 3500.00 12/200+8/100 1750.00 12/275

3 3471.88 12/250+8/200 1735.94 12/285

4 3330.70 12/250+8/200 1665.35 10/250

5 3143.16 12/250+8/200 1571.58 10/250

6 2904.72 12/250+8/200 1452.36 10/250

7-12 2619.80 10/250+8/200 1309.90 10/250

WTDY = 1.6 * WACI


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TDY Normal Ductility Walls vs

EC8 DC-M (Medium Ductility) Walls

Utilizes momentsobtained from analysis

For every section ofthe wall, Ve = 2.0 Vd

No shear forceenvelope

Forms boundaryregions

Utilizes momentenvelope as in highductility design

Base Shear Design

Moment Ve = 1.5 Vd For dual systems,

shear force envelopemust be used as in

high ductility design Forms boundaryregions

TDYTDY--20072007 EC8, DCEC8, DC--M WallsM Walls


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Discussions

Normal ductility shear walls are neither

similar to ordinary shear walls of ACI norDC-M walls of EC8

The amount of reinforcement required by

TDY for normal ductility walls issignificantly more than what ACI requires

The design forces used for designingnormal ductility walls are less than theones required for the design of DC-Mwalls


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Conclusions


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High Ductility Walls

We have to decide

whether we want to usecapacity design approachin shear wall design

YES! NO!

The current section for the

high ductility walls shouldbe rewritten

The current equations do not

calculate the design forcescorrectly, they must bemodified

?


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Normal Ductility Walls

We have to decide whether we

want to construct ductile wallseverywhere in Turkey

YES! NO!

Current specifications fornormal ductile walls arenot sufficient to providesuch ductility

We are puttingsignificant amount

of unnecessaryreinforcement to theshear walls

?


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Thank you

Questions?

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ComparativeShearWallDesign - Kurc