performence check for building designed with nbc, is

8/2/2019 Performence Check for Building Designed With NBC, Is

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Check for Performance of Building

Designed with NBC and IS Codes



TASKS

• Study of IAEE Manual( Guidelines for EarthquakeResistant Non-Engineered Construction)

• Comments on Existing NBC 205

•

Nonlinear static analysis of Building designed withNBC 205,105 and IS 1893,2002 for life safety

criteria

• Recommendations for further work



Methodology Select Building

Code

NBC 205 NBC 105/IS 1893,2002

Prepare Analysis

Building Model

Analyze building and design as

per selected code

Select Design load level and Load

factors from Selected code

Produce Beam and column Reinforcement detailing



Methodology

Determine, Capacity

Curve, Demand Curve

and Performance point

Development of Pushover

hinges for Beam and column

Nonlinear Static ,Pushoveranalysis

Select Codal Response spectra and

evaluate Spectra parameter Ca, Cv

Repeat the whole process

till satisfaction of Life

safety criteria

Life

safety

Criteria?

Does not

Meet

Increase design force level,

Modification in codal

provision



Methodology

Determine, Capacity

Curve, Demand Curve

and Performance point

Repeat Nonlinear Static,Pushover analysis

Upgrade Codal Response spectra and

evaluate Spectra parameter Ca, Cv

Repeat the whole

process till satisfaction

of Life safety criteria

Need to upgrade

performance

level?

Does notMeet

Increase design force

level,

Modification in codal

provision

Life

safety

Criteria

Recommend New Design Response spectrum

curve and load factors

Use this spectra for

design of representative

nos of models

Compile detailing outputs

And recommend in NBC

205

No Use Codal spectra

for design of

representative nosof models

Compile detailing

outputs

And recommend

in NBC 205



Nonlinear Static Pushover analysis

Push-over Curve

Load Vs. DeflectionVb

UN

UN F

Vb



Analysis Building Model

4.5 m

3.5 m

3.35 m

5X 3 Bays

Vertical Loadings are confirming to

NBC 102, 103

Steel :Fe 415



Performance check for Building

Detailed with NBC 205



Beam Detailing , NBC 205



Beam Detailing , NBC 205

Beam Size: 230 X 325



Column Detailing, NBC 205



NBC 205, Column Detailing



Pushover Hinges; beam moment

A

B

C

D

E

M/My

Curvature/SF

Yield Moment, My : From Analysis of section with Material partial factor of safety = 1

Steel ultimate strength = 1.25*steel yield strength

Hysteresis Type: Isotropic



Column Hinge

• Column hinge is based up on Interaction diagram of

column

• Removing partial factor of safety for concrete and steel

•

Ultimate strength of steel = 1.25*yield strength{ Fema356}



Selection of Response Spectra



300 YRS Return Period PGA Distributions



Response Spectra Parameter: Ca, Cv

Ground Acceleration, Ca = 0.32gStructural Response ,Acceleration at 1 sec, Cv =0.4g

0.32 g

0.32 g*2.5 =0.8g

0.32 g*2.5/2 =0.4 g

NBC Fits Response spectra with IS

Response spectra:



Pushover Analysis Output, PUSH X

Just before Structural instability:

Total nos of elastic hinge: 198 Nos

Total Immediate occupancy Hinge: 114 Nos

Total life safety hinge: 6 nos

Total Collapse prevention hinge: 14 Nos

Column Need to be strong for avoiding Collapse prevention hinge in

column

IO LS



ATC 40, Global Building Acceptability

Limits

0.33*0.08 =0.0264

0.01*10050 =100.5 mm 100.5mm to 201 mm

Top Story Displacementlimits

265.32 mm



ATC 40 Capacity Spectrum;

Earthquake: 300 Years of Return period

Earthquake: 300 years Return period

Target base shear: 923.544 KN

Target Displacement: 127.27 mm

Corresponding Inter story Drift: 127.27/(10050)=0.013 < 0.02( Damage control,0.01 to 0.02)

Life Safety Limit is ensured for 300 Years Return period

Push X



PUSHX, Capacity Curve and Elastic Response

L

S

L

C

P

LE

I

D

I

0

L Ductility Demand > Available Ductility

=> For Higher earthquake there will be

no ductility



Pushover Analysis Output, PUSH Y





Total Collapse prevention hinge: 30 Nos

Column Need to be strong for avoiding Collapse prevention

hinge

IO LS



ATC 40, Capacity Spectrum









PUSHY Capacity Curve and

Elastic response

L

S

L

C

P

LEI

D

I

0

LDuctility Demand > Available Ductility

=> For Higher earthquake there will be

no ductility



Check For NBC205 Designed Building

For 500 YRS RP Earthquake



26

500 YRS RP Ground Acceleration

Distributions



27



500 Yrs Response Spectra Parameter: Ca, Cv

Ground Acceleration, Ca = 0.36gStructural Response, Acceleration at 1 sec, Cv

=0.45g

0.36 g

0.36 g*2.5 =0.9g

0.36 g*2.5/2 =0.45g



ATC40 Capacity Spectra for 500 yrs return period

Earthquake

Capacity Curve and Demand curve do not meet:

This is due to formation of collapse prevention

hinges in columns and high seismic loading both

PUSH X



ATC40 Capacity Spectra for 500 yrs return

period Earthquake

PUSH X

Capacity Curve and Demand curve do not meet:

This is due to formation of collapse prevention

hinges in columns and high seismic loading both



Check for Performance of NBC105

Designed Building :

300 YRS RP Earthquake ResponseSpectra



NBC 105, Seismic Load



NBC 105, Seismic Force Distribution

54.55 KN

218.21 KN

304.03 KN



NBC105;

End Beam

Design

Output

Beam:

230 X 350



Column Design Output, NBC105



Response Spectra Parameter: Ca, Cv For 300 YRS RP

Ground Acceleration, Ca = 0.32g

Structural Response ,Acceleration at 1 sec, Cv

=0.4g

0.32 g

0.32 g*2.5 =0.8g

0.32 g*2.5/2 =0.4 g





PUSH X Output



Target Displacement: 92 mm

Corresponding Inter story Drift: 92/(10050)=0.01 < 0.02( Damage control,0.01 to 0.02)




Pushover Analysis Output, PUSH X




Total life safety hinge: 68 nosTotal life safety to collapse prevention hinge: 18 nos

Total Unstable hinge: 4 Nos


hinge

IO LS



Capacity Curve and Elastic Response

L

S

L

E

I

D

I

0

L

Ductility Demand> Available Ductility=> For Higher earthquake there will be no

ductility

Same as recommended in

Seismic hazard mapping and

risk assessment for Nepal







Target Displacement: 91 mm

Corresponding Inter story Drift: 91/(10050)=0.01 < 0.02( Damage control,0.01 to 0.02)


PUSH Y Output




L

S

L

E

I

D

I

0

L

Ductility Demand> Available Ductility

=> For Higher earthquake there will be no

ductility

Same as recommended in

Seismic hazard mapping and

risk assessment for Nepal



Check For NBC 105 Designed Building

For 500 YRS RP Earthquake





=0.45g

0.36 g

0.36 g*2.5 =0.9g

0.36 g*2.5/2 =0.45g




period Earthquake

PUSH X




period Earthquake

PUSH Y

Performance point does not meet in Y direction

Buildings designed for 300 YRS RP is Not safe in 500 YRS RP Earthquake

Demand curve above capacity curve indicates need of increase in design force level

Performance point

Not available



Check For Modified NBC 105 DesignedBuilding For 500 YRS RP Earthquake

Proposed Modification in NBC 105

Considers Basic seismic Coefficient of

0.09 instead of 0.08



Proposed Response spectrum: 10% in 50 years( 500 YRS RP)

Short period spectral acceleration: 0.9 g

Ground acceleration: 0.36 g

1 Sec , Spectral acceleration : 0.45 g





=0.45g

0.36 g

0.36 g*2.5 =0.9g

0.36 g*2.5/2 =0.45g

C= Ct*Z*I*K= 0.09

Load factors are remains

as it is

0.045/T

0.09/T0.09

0.036/T



Seismic Load

NBC 105, Modified Response spectra



Seismic Load Distribution

61.37 KN

245.48 KN

342.04 KN



Beam Design output

Beam 230X350



Column Design Output



ATC40 Capacity Spectra for 500 yrs return period

Earthquake






PUSH X



PUSH X , Output





Total life safety to collapse prevention hinge: 10 nos



hinge

IO LS




L

S

L

E

I

D

I

0

L

Ductility Demand> Available Ductility

=> For Higher earthquake there will be no

ductility



PUSH X , Output





Total life safety to collapse prevention hinge: 14 nos



hinge

IO LS



Building with Additional , SCWB Satisfying condition

500 YRS Return period 1000 YRS Return period

300 YRS Return Period

Strong column Weak beam condition

improves linear ductility



Check for performance level for IS

1893,2002 Designed Building

500 YRS RP Response Spectra



500 Years Return period

IS 1893, 2002, Response spectra

0.36 g

0.45 g



Response Spectra Parameter: Ca, Cv

Ca =0.36Cv=0.45



Evaluation of Seismic Static Load:• Seismic wt, W =Wt of the

building due to DL+0.25LL

• Base shear = Ah* W

• W= W1+W2+W3

• Z = zone factor

• I =Importance factor

• R = response reduction factor

• Sa/g = Spectral acceleration

coefficients



S i i F Di t ib ti



Seismic Force Distribution

61.4 KN

245.5 KN

342.0 KN





period Earthquake

PUSH X








C it C d El ti R




Ductility Demand is very close to Available

Ductility but still lacking in ductility

Conclusion



Conclusion

• Building Detailed with NBC 205

– Meets life safety criterion for 300

– No global linear ductility for higher earthquake

– Failure in 500 Yrs RP Earthquake

Conclusion



Conclusion

• Building Detailed with NBC 105

– Meets life safety criterion for 300

– No global linear ductility for higher earthquake

– Failure in 500 Yrs RP Earthquake



Conclusion

• Building Designed with Modified NBC 105 Response

spectra

– Life safety criteria meets for 500 YRS RP Earthquake

– Needs more global ductility for ensuring collapse

prevention for higher earthquake



Recommendations

•

Replace 300 Yrs Response spectra with 500 yrsResponse spectra in NBC 105

• Add additional clause for strong column weak beamfor ensuring collapse prevention in higher earthquake

• Use modified NBC 105 for the analysis of Samplebuildings belongs to NBC 205

• Develop summary of detailing and replace old Existingdetailing



THANK YOU

performence check for building designed with nbc, is

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