05_Jia_Li_2013

SEISMIC ANALYSIS OF EXISTING REINFORCED CONCRETE STRUCTUREREINFORCED CONCRETE STRUCTURE

Jia LiHongchun Liuo gc u uYueh-hua TsaiSanjay Dankarj y

Bechtel Power Corp.

OUTLINE

PURPOSE

BACKGROUND

METHODOLOGY

ANSYS ANALYSIS ANSYS ANALYSIS

GTSTRUDL ANALYSIS

COMPARISON BETWEEN ANSYS AND GTSTRUDL

CONCLUSIONCONCLUSION

June 19-22, 2013, page-2

PURPOSE

June 19-22, 2013, page-3

PURPOSE

To evaluate the structural integrity of an existing reinforced concrete structure in a nuclear power plant for a major equipment

PURPOSE

concrete structure in a nuclear power plant for a major equipment upgrade under earthquake load.

June 19-22, 2013, page-4

BACKGROUNDBACKGROUND

June 19-22, 2013, page-5

Y-Y

STRUCTURE GEOMETRY

NN

CL

3'-0" 18'-0"

1'-6"

1'-6"

NWall @ North

4'-10 1/2"1'-6"4'-0"

Column @ North

19'-1 1/2"

3'-0"

2'-0"

2'-0"

3' 4 1/2"

X-XWall @ West

250kip Equipment

4'-10 1/2"

3-4 1/23'-0"

250kip Equipment

1'-6"

Column @ South

Wall @ South

June 19-22, 2013, page-6

PLAN VIEW OF CONCRETE STRUCTURE

3'-4 1/2"

Z-Z

1'-9"

4'-10 1/2" 4'- 10 1/2"

8’ 9”

1'-9"

7'-0"1'-6"Wall @ West

Door openings @ W ll @ W t

8’-9”

1' 9"

7'-0"

@ Wall @ West8’-9”

1'-9"

7'-0" 9’-9”

19' -1 1/2"

Y-Y

June 19-22, 2013, page-7

ELEVATION VIEW OF CONCRETE STRUCTURELOOKING WEST

BACKGROUND1. Existing calc evaluates 140kip equipment and seismic

restraint supports are located @ first elevated floor slab.2. Equipment weight has been increased to 250kip and the new

seismic restraint supports are located @ second elevatedfloor slab.

3 Th t t i i ll l t d f th 140ki3. The structure was originally evaluated for the 140kipequipment by hand calc, which used a 1.5 multi-mode factorand other simplified, conservative assumptions. Thus, thestructural evaluation would not pass for the increasedstructural evaluation would not pass for the increasedloading if the same approach was used.

4. In new evaluation, response spectrum analysis method isused which takes out conservatism in estimation of seismicforces and is widely used industry-wise.

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METHODOLOGY

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METHODOLOGY To remove conservatism in hand calculation, project decided to

use finite element analysis method. Solid element in ANSYS is

METHODOLOGY

ychosen to be used in the calculation.

To remove conservatism of using 1.5 multi-mode factor,Response Spectrum (RS) analysis is used.

OBE load combination is used since it is more critical than SSE.e.g.

SSE: 1.0D+1.0L+1.0E’OBE: 1.4D+1.7L+1.9EE’: SSE seismic loadE : SSE seismic loadE: OBE seismic load

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ANSYS ANALYSISANSYS ANALYSIS

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ANSYS MODEL

ANSYS Version 13.0 Solid element: SOLID185Solid element: SOLID185 Element size: 6” x 6” x 6” Boundary: Fixed at bottom

(with dowels)(with dowels) Nodes: about 40000 Elements: about 40000

Note: Elements in red are the columnsElements in white are the elevated floor slabsElements in cyan are the walls

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RESPONSE SPECTRUM ANALYSIS

Response Spectra (RS): 4% damping for OBE

M d i l d dModes included: 100

Mass Participation pPercentage:

X : >93%Y : >94%Z : >91%Z : >91%

Modal Combination: SRSS

Horizontal RS

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ZPA: 0.32gPeak Acceleration: 1.6g

FSUM command in ANSYS Version 13.0 is similar to LIST SUM

RS ANALYSIS IN ANSYS

FORCE command in GTSTRUDL, however it has some limitationswhen performing RS.

To reduce post processing time (72 Load Combinations) and to beTo reduce post-processing time (72 Load Combinations) and to beconservative in the calculation, the following method is used inANSYS for final structural evaluation:1 Perform Response Spectrum Analysis in each direction1. Perform Response Spectrum Analysis in each direction

2. Obtain accelerations from RS Analysis and associated seismic

mass at each node of the structuremass at each node of the structure

3. Apply the equivalent static seismic force (ELF) by multiplying the

corresponding acceleration and seismic mass at each node

4. OBE load combination is applied and 100-40-40 combination rule

is used for seismic load in three global directions.

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STRUCTURAL EVALUATION Following subcomponents are evaluated in the calculation:

1. North and South Columns2 N th d S th W ll l t d i l h ll2. North and South Walls evaluated as in-plane shear wall3. West Wall evaluated as in-plane shear wall4. Three elevated Floor Slabs 5. Whole section5. Whole section6. Slab @ bottom supporting the structure7. Dowels

Based on the evaluations, it is concluded that the existing concretestructure is structurally adequate for the upgraded equipment andseismic restraint support loads NO structural modification isseismic restraint support loads. NO structural modification isrequired.

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GTSTRUDL ANALYSIS

The objective of GTSTRUDL analysis is to demonstrate that a simplified plate model could be a more practicala simplified plate model could be a more practical alternative for this type of application.

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GTSTRUDL MODEL

Element Type GTSTRUDL MODEL

ypin GTSTRUDL 1 2 3

Walls & Slabs PLATE PLATE PLATE

Columns PLATE BEAM BEAM

C tiConnections between Column

and Wall

Rigidly Connected

TYPE RIGID SOLID

Rigid Link Element

June 19-22, 2013, page-17

GTSTRUDL MODEL – 1PLATE ELEMENT

GTSTRUDL 31.0Plate elementPlate element:

SBHQ6 Element size:Element size:

6” x 6” Boundary Condition:

Fixed at bottomFixed at bottom Model Size:

about 10000 Nodesabout 10000 Elementsabout 10000 Elements

June 19-22, 2013, page-18

GTSTRUDL MODEL – 2PLATE & BEAM ELEMENTPLATE & BEAM ELEMENTTYPE RIGID SOLID EVERY 6” ALONG COLUMN HEIGHT

GTSTRUDL 31 0GTSTRUDL 31.0Plate element:

SBHQ6B l tBeam element :

for columns onlyElement size:

6” 6”6” x 6” Boundary Condition:

Fixed at bottomXX

Model Size:about 10000 Nodesabout 10000 Elements Z

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X Y

GTSTRUDL MODEL – 3PLATE & BEAM ELEMENTPLATE & BEAM ELEMENTRIGID LINK: 6” X 6”, E=100xEcRIGID LINK EVERY 6” ALONG COLUMN HEIGHT

Node at wallNode at column

Node at wall

Rigid link

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MODAL ANALYSIS COMPARISON

ANSYS_SOLID

Mode Freq Mass Participation Direction

Total Weight

GTSTRUDL_PLATE (GT1)

M d Freq Mass P ti i ti Di ti

Total W i htMode q

(Hz) Participation Factor

Direction Weight (kip)

1 16.13 62% Y6714 34.72 50% X

Mode q(Hz) Participatio

n FactorDirection Weight

(kip)

1 15.97 63% Y6864 33.62 58% X

10 81.68 67% Z

GTSTRUDL RIGID LINK (GT3)GTSTRUDL RIGID SOLID (GT2)

10 79.49 67% Z

GTSTRUDL_RIGID LINK (GT3)

Mode Freq (Hz)

Mass Participation

FactorDirection

Total Weight

(kip)

GTSTRUDL_RIGID SOLID (GT2)

Mode Freq (Hz)

Mass Participation

FactorDirection

Total Weight

(kip)

1 16.23 63% Y6864 33.71 61% X

10 79.45 63% Z

1 16.28 63% Y6864 33.84 61% X

10 79.55 64% Z

June 19-22, 2013, page-21

MODAL ANALYSIS COMPARISON

GT2_PL GT3 PLA (GT1- (GT2- (GT3-

Comparison Item

GT1_PLATE

ATE RIGID SOLID

GT3_PLATE RIGID

LINK

ANSYS_SOLID

(GT1-ANSYS) /ANSYS

(GT2-ANSYS) /ANSYS

(GT3-ANSYS) /ANSYS

(1) (2) (3) (4) {(1)-(4)}/(4)

{(2)-(4)}/(4)

{(3)-(4)}/(4)

Mode 1 (Hz) 15.97 16.28 16.23 16.13 -0.99% 0.93% 0.62%( ) % % %

Mode 4 (Hz) 33.62 33.84 33.71 34.72 -3.17% -2.53% -2.91%

Mode 10 (Hz) 79 49 79 55 79 45 81 68 2 68% 2 61% 2 73%Mode 10 (Hz) 79.49 79.55 79.45 81.68 -2.68% -2.61% -2.73%

Weight (kip) 686 686 686 671 2.24% 2.24% 2.24%

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COMPARISON BETWEEN SOLID ELEMENT AND SOLID ELEMENT AND PLATE ELEMENT

June 19-22, 2013, page-23

STATIC ANALYSIS RESULTS BETWEEN STATIC ANALYSIS RESULTS BETWEEN

ANSYS SOLID ELEMENT AND

GTSTRUDL PLATE ELEMENT

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STATIC LOAD CASE COMPARISON

N

Load Case Force DifferenceDead 3.00%Live 7.00%

O YRes_EW 0.03%Res_WE 0.03%Res_SN 0.02%Res_NS 0.02%

GTSTRUDL: LIST SUM FORCEANSYS: FSUM

X

Section cut @ bottom for whole section.

ANSYS: FSUM

June 19-22, 2013, page-25

@Z is vertical up.O is the point for moment summation.

RESPONSE SPECTRUM ANALYSIS BETWEEN

ANSYS SOLID ELEMENT AND ANSYS SOLID ELEMENT AND

GTSTRUDL PLATE ELEMENT

June 19-22, 2013, page-26

FX COMPARISON

N

SHEAR ALONG EAST-WEST

ItemGTSTRUDL ANSYS

DifferencekipRS_X 133.58 118.16 13.05%RS_Y 19.07 24.06 ‐20.74%RS_Z 5.67 10.64 ‐46.75%

100‐40‐40 143.47 132.04 8.66%O Y


X


June 19-22, 2013, page-27


FY COMPARISON

N

SHEAR ALONG NORTH-SOUTH

ItemGTSTRUDL ANSYS

Differencekip

RS_X 19.07 24.06 ‐20.74%

O YRS_Y 244.91 233.02 5.10%RS_Z 4.52 5.60 ‐19.19%

100‐40‐40 254.35 244.88 3.87%


X


June 19-22, 2013, page-28


FZ COMPARISON

N

AXIAL FORCE

ItemGTSTRUDL ANSYS

DifferencekipRS_X 6.28 10.65 ‐41.04%RS Y 5 01 5 60 10 45%

O Y

RS_Y 5.01 5.60 ‐10.45%RS_Z 134.22 145.05 ‐7.47%

100‐40‐40 138.74 151.55 ‐8.45%


X


June 19-22, 2013, page-29


MX COMPARISON

N

MOMENT ABOUT X-X

GTSTRUDL ANSYSItem

GTSTRUDL ANSYSDifferencekip‐in

RS_X 5097.83 6223.22 ‐18.08%RS Y 57403 46 55530 89 3 37%

O Y

RS_Y 57403.46 55530.89 3.37%RS_Z 1538.23 886.06 73.60%

100‐40‐40 60057.88 58374.60 2.88%


X


June 19-22, 2013, page-30


MY COMPARISON

N

MOMENT ABOUT Y-Y

ItemGTSTRUDL ANSYS

Differencekip‐inRS_X 32324.98 28795.82 12.26%

O Y

RS_Y 4337.56 5903.56 ‐26.53%RS_Z 3104.34 2819.29 10.11%

100‐40‐40 35301.74 32284.96 9.34%


X


June 19-22, 2013, page-31


MZ COMPARISON

N

MOMENT ABOUT Z-Z

ItemGTSTRUDL ANSYS

Differencekip‐inRS_X 5002.85 7933.47 ‐36.94%RS Y 6279 24 6255 55 0 38%

O Y

RS_Y 6279.24 6255.55 0.38%RS_Z 1246.32 788.46 58.07%

100‐40‐40 8013.07 10751.08 ‐25.47%


X


June 19-22, 2013, page-32


COMPARISON BETWEEN

ELF AND RS ANALYSISELF AND RS ANALYSIS

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ENVELOP SECTION CUT RESULTS

N

ItemFXX FYY FZZ MXX MYY

kip kip kip kip*in kip*in

RS 155.6 287.3 1365.7 157167.8 64979.4

ELF 457.6 814.4 1424.8 180916.5 120541.3O Y

RS: Response Spectrum AnalysisELF: Equivalent Static Seismic Force explained in Page 14

Xin Page 14.Envelop values from 72 load combinations are listed in the table above.

June 19-22, 2013, page-34

Section cut @ bottom for whole section.Z is vertical up.O is the point for moment summation.

SECTION P-M (RS)

42000kip

100000ki ft100000kip-ft

Rotation angle: 220

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SECTION P-M (ELF)

42000kip

110000kip-ft

Rotation angle: 340

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CONCLUSIONSCONCLUSIONS

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CONCLUSIONS Response Spectrum Analysis is a much more reasonable methodthan equivalent static analysis using a 1.5 multi-mode factor. It ismore practical to use RS analysis in evaluation of existing structure.

GTSTRUDL’s Shell element is a much more simplified element thanANSYS’s SOLID element and the results from GTSTRUDL’s shellelement are comparable to ANSYS’s SOLID elementelement are comparable to ANSYS s SOLID element.

GTSTRUDL’s RSA is reliable and easy to use. Various results(d fl ti b h t ) b il t t d t d(deflections, base shear etc) can be easily output and post processedto meet engineer’s needs. List Sum Force Command in GTSTRUDL isvery useful in RSA.

Use of rigid Link or TYPE RIGID SOLID in GTSTRUDL may introduceadditional stiffness to the structure.

June 19-22, 2013, page-38

Q&A?Q&A?

June 19-22, 2013, page-39

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