Capacity Assessment of RC Subassemblages Upgraded with CFRP

Abstract

Many gravity load designed (GLD) reinforced concrete (RC) structures located in seismic areas are in need of upgrade. As an alternative to traditional upgrade solutions, an innovative technique based on the use of Fiber Reinforced Polymer (FRP) composites was proposed and experimentally validated. The technique consists of strengthening reinforced concrete connections by means of the combined use of FRP laminates and FRP near surface mounted (NSM) bars. In parallel, a theoretical approach for the assessment of the connection capacity was developed based on the analysis of each component (i.e., column, beam and joint), in order to determine which component controls failure. The outcomes of the analysis were compared to the experimental results with considerations on the reliability of the approach and aspects slated for future investigations. The behavior of the FRP-confined column cross section was also analyzed and it is herein discussed based on recorded strains in internal steel bars and FRP jacket.

Get full access to this article

View all access options for this article.

References

1. Bonacci, J.F., and Wight, J.K. (1996). Displacement-Based Assessment of Reinforced Concrete Frames in Earthquake, ACI Publication SP 162: 117-133.

2. ACI-ASCE Committee 352 (1985). Recommendations for Design of Beam-Column Joints in Monolithic Reinforced Concrete Structures, American Concrete Institute, Detroit USA .

3. Prota, A., Nanni, A., Manfredi, G. and Cosenza, E. (2002). Selective Seismic Strengthening of RC Frames with Composites , In: Proceeding CD-ROM of the Seventh U.S. National Conference on Earthquake Engineering, Boston, Massachusetts, July 21-25, 2002, sponsored by the Earthquake Engineering Research Institute, Paper N. 383.

4. Realfonzo, R., Prota, A., Manfredi, G. and Pecce, M. (2002). Flexural Strength of FRP-Confined RC Columns , In: Proceedings of the First fib Congress: Concrete Structures in the 21st Century, 13-19 October 2002, Osaka, Japan.

5. Spoelstra, M.R. and Monti, G. (1999). FRP-confined Concrete Model , ASCE Journal of Composites for Construction, 3(3): 143-150 .

6. Mander, J.B., Priestley, M.J.N. and Park, R. (1988). Theoretical Stress-strain Model for Confined Concrete , ASCE Journal of Structural Engineering, 114(8): 1824-1826 .

7. ACI Committee 440. (2001). Guide for the Design and Construction of Concrete Reinforced with FRP Bars, 440.1R-01. American Concrete Institute, Farmington Hills, MI .

8. Paulay, T. and Priestley, M.J.N. (1992). Seismic Design of Reinforced Concrete and Masonry Buildings, John Wiley & Sons, Inc., New York .

9. Priestley, M.J.N., Seible, F. and Calvi, G.M. (1996). Seismic Design and Retrofit of Bridges, John Wiley & Sons, Inc., New York .

10.

10. Priestley, M.J.N. (1997). Displacement-Based Seismic Assessment of Reinforced Concrete Buildings , Journal of Earthquake Engineering, 1(1): 157-192 .

11.

11. Kupfer, B.H. and Gerstle, K.H. (1973). Behavior of Concrete under Biaxial Stresses , Journal of the Engineering Mechanics Division, 99(4): 853-866 .

12.

12. ATC40 (1996). Seismic Evaluation and Retrofit of Concrete Buildings, California Seismic Safety Commission, Report SSC 96-01.