Seismic Vulnerability and Retro Fit of RC Flat Plate Structure


  • Chittagong University of Engineering and Technology, Department of Civil Engineering, Bangladesh


Flat-plate system has become one of the most popular practices now-a-days, primarily for architectural flexibility, use of space, easier formwork and shorter construction time. However, the structural efficiency of the flat-plate is hindered by its poor performance under earthquake loading. Post-earthquake observations and experimental testing have shown that lateral movements induced by earthquake can make the connections between slabs and columns susceptible to punching shear failures. Though Reinforced Concrete Frame (RCF) is widely used in Bangladesh, flat-plate constructions are also becoming a common practice. BNBC and ACI have suggested that flat-plate frames can be designed either by Direct Design or Equivalent Frame Method. The present study deals with the seismic evaluation of existing flat plate structure using inelastic method (Pushover analysis). The load-deformation curve (i.e. capacity curve) is obtained using ETABS. The performance point has been determined by superimposing the capacity spectrum with the normalized response spectra for 5% damping ratio as mentioned in BNBC. The methods for evaluating the performance level have been determined using procedures presented in FEMA-356 and ATC-40. Many existing flat plate buildings in Bangladesh may not have been designed for seismic forces. Hence, it is important to study their response under seismic conditions and to evaluate seismic retrofit schemes. Based on the seismic evaluation results, two possible retrofit techniques were applied to improve the seismic performance of an existing Nine-storied flat plate building which was considered as a model representative of all flat plate buildings in Bangladesh.


Punching Shear, Pushover, Retrofit, Unbalanced Moment.

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“Bangladesh National Building Code (BNBC), 2006", Housing and Building Research Institute, Mirpur, Dhaka, Bangladesh.

“Seismic Evaluation and Retrofit of Concrete Building (volume 1)", Applied Technology Council (ATC)-40, California Seismic Safety Commission, USA.

“Pre-standard and Commentary for the Seismic Rehabilitation of Buildings", Federal Emergency Management Agency (FEMA)-356, 2000, Washington, D. C., USA.

Computer and Structures Inc., ETABS Nonlinear Version 9.7.0, Berkeley, California, USA.

“Seismic Evaluation of Reinforced Concrete Buildings", Singh Taranpreet, Kwatra Naveen, PhD, Master’s Thesis, Department of Civil Engineering, Thapar Institute of Engineering and Technology, Patiala, India.

“Study on Seismic Performance of Existing Buildings in Romania", Postelnicu Tudor, Cotofana Dragos, Chesca Basarab, Ionescu Raluca, Vacareanu Radu, Technical University of Civil Engineering, Bucharest, Romania.

“Seismic Performance of Flat-Slab Building Structural Systems. Apostolska R. P., Necevska Cvetanovska 2 G. S., Cvetanovska J. P., and Mircic N., The 14th World Conference on Earthquake Engineering (14WCEE) October 12-17, 2008, Beijing, China.

Elements of Earthquake Engineering (second edition)", Krishna Jai, Chandrasekaran A. R., Chandra Brijesh.

“Seismic Performance of Existing RC Flat-Plate Structures", Alam M. Jahangir, PhD and Paul Ajoy published in the 9th International Conference on Earthquake Engineering (9CUEE) and 4th Asia Conference on Earthquake Engineering (4ACEE), 6-8 March 2012, Tokyo Institute of Technology, Tokyo, Japan. Paper ID: 11-373.

“Earthquake Resistant Design of Structures" Agarwal Pankaj, Shrikhande Manish.

“Geotechnical Earthquake Engineering", Kramer Steven L., University of Washington, PrenticeHall International Series in Civil Engineering and Engineering Mechanics.

“Performance Based Seismic Design of Buildings", Sood Sudhanshu, Kwatra Naveen, PhD, Master’s Thesis, Department of Civil Engineering, Thapar University, Patiala, India.

“Seismic Performance of Reinforced Concrete Frames", Kashyap Jaya, Master’s Thesis, Department of Civil, Environmental and Mining engineering, University of Adelaide, Australia.

“Evaluation of the Seismic Performance of Reinforced Concrete Buildings", Bagchi Ashutosh, PhD Thesis, Department of Civil and Environmental Engineering, Carleton University, Ottawa, Canada.

“Generation of Liquefaction Potential Map for Chittagong City Area", Alam M. Jahangir, Bhuiyan A. Rahman, Roy Tuhin, Barua A. K., 4th International Conference on Earthquake Engineering, Taiwan, 2006.

“Design of Concrete Structures", Thirteenth Edition, Nilson Arthur H., Darwin David, Dolan Charles W.

“Earthquake Resistant Design of Structures" Pankaj Aarwal, Manish Shrikhande.

FEMA 356, 273, (2002), “Pre-standard and Commentary for the Seismic Rehabilitation of Buildings", Federal Emergency Management Agency, Washington, D. C., USA.

“Reinforced Concrete Design", Fourth Edition, Wang Chu-Kia, Salmon Charles G.

“Explanatory Examples on Indian Seismic Code IS 1893 (Part I)", Jain Sudhir K., IITK-GSDMA-EQ21-V2.0.

“Non-Linear Pushover Analysis of Flat slab Building by using SAP2000", Priya K. Soni, Durgabhavani T., Mounika K., Nageswari M., Poluraju P.

“Nonlinear Static Analysis of RCC Frames (Software Implementation ETABS 9.7)", Shah Mrugesh D., Patel Sumant B.

“Performance Based Pushover Analysis of RCC Frames", Pambhar Dakshes J.


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