This document describes a study on evaluating the performance of non-ductile reinforced concrete frames retrofitted with infill walls and added struts using pushover analysis. The objectives are to analyze frames with and without infill, and retrofitted frames with struts added to strengthen soft stories or interior bays. The methodology involves modeling the frames and retrofits, defining hinge properties, and conducting pushover analysis. The results show infill walls alter the collapse mechanism, and retrofitting by gradually strengthening interior bays into a spine has better performance than other retrofitting methods.

1. Aslam Faqeer Mohammad
Structural Engineer
Assistant Professor
Department of Civil Engg.
NED University of Engg.
& Tech., Karachi, Pakistan
maslam@neduet.edu.pk
Tehmina Ayub
Assistant Professor
Department of Civil Engg.
NED University of Engg.
& Tech., Karachi, Pakistan
tehmina@neduet.edu.pk
N S Zafar
Assistant Professor,
Department of Civil Engg.
NED University of Engg.
& Tech., Karachi, Pakistan
najmsahar@neduet.edu.pk

2. 1) INTRODUCTION
2) OBJECTIVES
3) METHODOLOGY
4) RESULTS
5) CONCLUSION

3. INRTODUCTION
In Pakistan, non-engineered non-ductile construction is quite common causing
severities to huge stock of existing buildings during an earthquake.
Earlier in nineteen century, the structural engineering design was mainly
dependent on the linear structural capacity of the building and the code specified
design loads on the building, neglecting the nonlinear behavior. In recent years,
importance of nonlinearity has been identified as a major designing parameter
especially in the high seismic zones.
The most appropriate way to assess the performance of structure subjected to
earthquake action is nonlinear time history (NLTH) analysis. But nonlinear time
history analysis (NLTH) is time consuming process, so now how to get the quick
information about the performance of structure and the results is “Nonlinear
Static Pushover” (NSP) method.
INRTODUCTION
In Pakistan, non-engineered non-ductile construction is quite common causing
severities to huge stock of existing buildings during an earthquake.
Earlier in nineteen century, the structural engineering design was mainly
dependent on the linear structural capacity of the building and the code specified
design loads on the building, neglecting the nonlinear behavior. In recent years,
importance of nonlinearity has been identified as a major designing parameter
especially in the high seismic zones.
The most appropriate way to assess the performance of structure subjected to
earthquake action is nonlinear time history (NLTH) analysis. But nonlinear time
history analysis (NLTH) is time consuming process, so now how to get the quick
information about the performance of structure and the results is “Nonlinear
Static Pushover” (NSP) method.
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

4. PUSHOVER ANALYSIS
Pushover analysis is a static, nonlinear procedure in which the magnitude of the
structural loading is incrementally increased in accordance with a certain predefined
pattern. With the increase in the magnitude of the loading, weak links and failure
modes of the structure are found. Normal engineering analysis assumes linear elastic
behavior for structural members, which fail to reliably account for redistribution of
forces due to member nonlinear behavior and dissipation of energy due to material
yielding.
PUSHOVER ANALYSIS
Pushover analysis is a static, nonlinear procedure in which the magnitude of the
structural loading is incrementally increased in accordance with a certain predefined
pattern. With the increase in the magnitude of the loading, weak links and failure
modes of the structure are found. Normal engineering analysis assumes linear elastic
behavior for structural members, which fail to reliably account for redistribution of
forces due to member nonlinear behavior and dissipation of energy due to material
yielding.
The ATC-40 (1996) and ASCE 31 documents have developed modeling
parameters and acceptance criteria for pushover analysis
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

5. MODELING PARAMETERS AND
ACCEPTANCE CRITERIA
MODELING PARAMETERS AND
ACCEPTANCE CRITERIA
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

6. STEPS FOR PUSHOVER ANALYSIS
Step 1: Construction of General Response Spectrum
Step 2: Transformation into Demand Spectrum
Step 3: Construction of Pushover Curve
Step 4: Transformation into Capacity Spectrum
Step 5: Determination of Performance Level on the basis of Performance Point
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

7. RESULTS OF PUSHOVER ANALYSIS
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

8. OBJECTIVE
The performance based evaluation of non-ductile two
dimensional Reinforced Concrete frame with and without
infill, retrofitted by adding struts of variable strength in two
different ways
1. Retrofitting of soft storey
2. Retrofitting of only single interior bay gradually converting into a spine
OBJECTIVE
The performance based evaluation of non-ductile two
dimensional Reinforced Concrete frame with and without
infill, retrofitted by adding struts of variable strength in two
different ways
1. Retrofitting of soft storey
2. Retrofitting of only single interior bay gradually converting into a spine
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

9. Frame without infill Frame with Infill
MODEL DESCRIPTIONS
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

10. MODEL DESCRIPTIONS
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

11. AS PER ASCE 31
(Acceptance Criteria and Modeling Parameters)
M-PHI CURVE FOR BEAM FOR COLUMN
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

12. HINGE DEFINITION
FOR BEAM
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

13. FOR COLUMN
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

14. Frame without infill Frame with Infill
PUSHOVER CURVE
0
200
400
600
800
0 0.25 0.5 0.75 1
BaseShear(KN)
Displacements (m)
0
300
600
900
1200
1500
0 0.25 0.5
BaseShear(KN)
Displacements (m)
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

15. Frame without infill Frame with Infill
MECHANISM AT PERFORMANCE POINT
B IO LS CP C D EB IO LS CP C D E
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

16. RETROFITTED MODELS
Retrofitted Frame in Which Only Soft Story is Retrofitted (Model#03),
Retrofitted Frame in Which Single bay is Retrofitted Gradually Converting to Spine
(Model#04 to Model#09)
Model # 03 Model # 04 Model # 05 Model # 06
Model # 09Model # 08
Model # 07
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

17. PUSHOVER CURVES OF RETROFITTED MODELS
Retrofitted Frame in Which Only Soft Story is Retrofitted (Model#03),
Retrofitted Frame in Which Single bay is Retrofitted Gradually Converting to Spine
(Model#04 to Model#09)
Model # 03 Model # 04 Model # 05 Model # 06
Model # 09Model # 08Model # 07
0
400
800
1200
1600
0 0.1 0.2 0.3 0.4 0.5
BaseShear(KN)
Displacements (m)
0
500
1000
1500
2000
0 0.1 0.2 0.3 0.4 0.5 0.6
BaseShear(KN)
Displacements (m)
0
500
1000
1500
2000
2500
0 0.1 0.2 0.3
BaseShear(KN)
Displacements (m)
0
500
1000
1500
2000
2500
3000
0 0.1 0.2 0.3
BaseShear(KN)
Displacements (m)
0
1000
2000
3000
0 0.1 0.2 0.3
BaseShear(KN)
Displacements (m)
0
1000
2000
3000
0 0.1 0.2 0.3
BaseShear(KN)
Displacements (m)
0
1000
2000
3000
0 0.1 0.2 0.3
BaseShear(KN)
Displacements (m)
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

18. MECHANISM AT PERFORMACE POINT OF RETROFITTED MODELS
Retrofitted Frame in Which Only Soft Story is Retrofitted (Model#03),
Retrofitted Frame in Which Single bay is Retrofitted Gradually
Converting to Spine (Model#04 to Model#09)
Model # 03 Model # 04 Model # 05 Model # 06
Model # 09Model # 08Model # 07
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION

19. CONCLUSION
1. The presence of infill significantly alters the collapse
mechanism of bare frame.
2. The performance of spine wise retrofitted model is
better than other retrofitted model.
CONCLUSION
1. The presence of infill significantly alters the collapse
mechanism of bare frame.
2. The performance of spine wise retrofitted model is
better than other retrofitted model.
INTRODUCTION
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSION