Seismic strengthening of columns by adding new concrete
DOI:
https://doi.org/10.5459/bnzsee.40.2.49-68Abstract
Placing reinforced concrete jackets or layers to strengthen or repair and strengthen concrete columns is a normal construction practice but there are many unresolved issues regarding the capacity of the strengthened elements. In the absence of any guidance, engineering judgement is often used. This paper sets out to assist the engineer when considering some of these unresolved issues. Revised values for factors of safety are proposed for design. A procedure to guarantee a sufficient connection between contact surfaces and to determine the performance of retrofitted columns is presented, considering the strengthened columns as “composite” elements. The parameters affecting the main mechanisms for the transfer of shear stress at the interface between new and old concrete are described and practical design considerations are given. An approximate procedure is presented, based on the design of monolithic elements, supplemented by the use of specific modification factors (monolithic factors), in order to evaluate the capacity of a strengthened element. Available experimental results are processed to derive appropriate values for monolithic behaviour factors and an extended analytical analysis is used to fill in gaps in the experimental work. Although this paper has particular relevance to seismic strengthening, its contents will have a wider application to strengthening in general. The object of this paper is to provide guidance so that the engineer is better equipped to deal with the practical design needs of today.
References
ANSYS (2002). “User’s Maual”. The Element Library, ANSYS Element Reference, ANSYS Release 6.1. SAP IP, Inc..
ATC 40 (1996). “Seismic Evaluation and Retrofit of Concrete Buildings”. Applied Technology Council, Vol. 1, California, USA.
Bett, B. J., Klinger, R. E. and Jirsa, J. O. (1988). “Lateral Load Response of Strengthened and Repair Reinforced Concrete Columns”. ACI Structural Journal, Vol. 85, No. 5, pp. 499-508.
Bousias, S., Spathis, A. L. and Fardis, M. N. (2004). “Seismic Retrofitting of Columns with Lap-splices via RC Jackets”. Proceedings of the 13th World Conference on Earthquake Engineering, Vancouver, Canada, paper No. 1937.
CEB Bul. No. 162 (1983). “Assessment of Concrete Structures and Design Procedures for Upgrading (Redesign)”. Bulletin D’Information, Comite Eurointernational du Beton, Paris.
CEB/fib (1993). “CEB/fib Model Code 1990”. Comite Eurointernational du Beton. Published by Thomas Telford, London.
Cervenka, V., Jendele, L. and Cervenka, J. (2005). “ATENA Program Documentation 2005. Part 1 Theory”. Prague.
Chai, Y. H., Priestley, M. J. N. and Seible, F. (1991). “Seismic Retrofit of Circular Bridge Columns for Enhanced Flexural Performance”. ACI Structural Journal, Vol. 88, No.5, pp. 572-584.
Chai, Y. H., Priestley, M. J. N. and Seible, F. (1994). “Analytical Model for Steel-Jacketed RC Circural Bridge Columns”. Journal of Structural Engineering (ASCE), Vol. 120, No. 8, pp. 2358-2376. DOI: https://doi.org/10.1061/(ASCE)0733-9445(1994)120:8(2358)
Dritsos, S. E. (1994). “Ultimate Strength of Flexurally Strengthened RC Members”. Proceedings of the 10th European Conference on Earthquake Engineering, Vienna, Vol. 3, pp. 1637-1642.
Dritsos, S. E. (1996). “Flexural Behaviour of Retrofitted RC Beams”. Proceedings of the 11th World Conference on Earthquake Engineering, Acapulco, paper No. 516.
Dritsos, S. E. (2005a). “Seismic Retrofit of Buildings: A Greek Perspective”. Bulletin of the New Zealand Society for Earthquake Engineering, Vol. 38, No. 3, pp. 165-181. DOI: https://doi.org/10.5459/bnzsee.38.3.165-181
Dritsos, S. E. (2005b). “Repairs and Strengthening of Reinforced Concrete Structures”. University of Patras, Patras, Greece. (In Greek).
Dritsos, S. E., Taylor, C. A. and Vandoros K. G. (1997). “Seismic Strengthening of Reinforced Concrete Structures by Concrete Jacketing”. Proceedings of the 7th International Conference on Structural Faults and Repair, 1997, Edinburgh, UK, Vol. 3, pp. 391-402.
EC 2 (2004). “Eurocode 2: Design of Concrete Structures. Part 1-1: General Rules and Rules for Buildings”. EN 1992-1-1: European Committee for Standardization, CEN/TC250, Brussels.
EC 4 (2002). “Eurocode 4: Design of Composite Steel and Concrete Structures. Part 1-1: General Rules and Rules for Buildings”. PrEN 1994-1-1, European Committee for Standardization, CEN/TC250, Brussels.
EC 8 (1995). “Eurocode 8: Design Provisions for Earthquake Resistance of Structures: Part 1-4: Strengthening and Repair of Buildings”. PrEN 1998-1-4: 1995. European Committee for Standardization, CEN/TC250, Brussels.
EC 8 (2004). “Eurocode 8: Design of Structures for Earthquake Resistance. Part 3: Assessment and Retrofitting of Buildings”. Draft No. 5. prEN 1998-3: European Committee for Standardization, CEN/TC250, Brussels.
Economou, M. (2004). “Monolithic Coefficients for RC Columns”. MSc Thesis, University of Patras, Greece. (in Greek).
Ersoy, U., Tankut, A. T. and Suleiman, R. (1993). “Behaviour of Jacketed Columns”. ACI Structural Journal, Vol. 90, No. 3, pp. 288-293.
FEMA 356 (2000). “Prestandard and Commentary for the Seismic Rehabilitation of Buildings”. Federal Emergency Management Agency, Washington, D.C..
fib (2001). “Externally Bonded FRP Reinforcement for Reinforced Concrete Structures”. Bulletin 14. Federation International du Beton, TG 9.3.
fib (2003). “Seismic Assessment and Retrofit of Reinforced Concrete Buildings”. State-of-art Report, Bulletin 24. Federation International du Beton, Lausanne.
Gomes, A. M. and Appleton, J. (1998). “Repair and Strengthening of Reinforced Concrete Elements Under Cyclic Loading”. Proceedings of the 11th European Conference on Earthquake Engineering, 1998, Paris, France. CD Proceedings.
GRECO (2005). “Greek Retrofitting Code”. Second draft version by the Greek Organization for Seismic Planning and Protection, Greek Ministry for Environmental Planning and Public Works, Athens, Greece. (In Greek).
Hakuto, S. (1995). “Retrofitting of Reinforced Concrete Moment Resisting Frames”. PhD Thesis, Department of Civil Engineering, University of Canterbury, New Zealand.
Julio, E. S., Branco, F. and Silva, V. D. (2003). “Structural Rehabilitation of Columns with Reinforced Concrete Jacketing”. Progress in Structural Engineering and Materials, Vol. 5, pp. 29-37. DOI: https://doi.org/10.1002/pse.140
Julio, E. S., Branco, F. and Silva, V. D. (2005). “Reinforced Concrete Jacketing – Interface Influence on Monotonic Loading Response”. ACI Structural Journal, Vol. 102, No. 2, pp. 252-257.
Lampropoulos, A. P. and Dritsos, S. E. (2006). “Numerical Prediction of Behaviour of Strengthened RC Columns under Cyclic Loading”. Proceedings of the 11th International Conference on Structural Faults and Repair, Edinburgh. CD Proceedings.
Panagiotakos, T. B. and Fardis, M. N. (2001). “Deformations of Reinforced Concrete Members at Yielding and Ultimate”. ACI Structural Journal, Vol. 98, No. 2, pp. 135-148.
Pauley, T. and Priestley, M. J. N. (1992). “Seismic Design of Reinforced Concrete and Masonry Buildings”. John Wiley and Sons Inc., New York. DOI: https://doi.org/10.1002/9780470172841
Priestley, M. J. N., Seible, F., Xiao, Y. and Verma, R. (1994a). “Steel Jacket Retrofitting of Reinforced Bridge Columns for Enhanced Shear Strength-Part 1: Theoretical Considerations and Test Design”. ACI Structural Journal, Vol. 91, No. 4, pp. 394-405. DOI: https://doi.org/10.14359/9885
Priestley, M. J. N., Seible, F., Xiao, Y. and Verma, R. (1994b). “Steel Jacket Retrofitting of Reinforced Bridge Columns for Enhanced Shear Strength-Part 2: Test Results and Comparison with Theory”. ACI Structural Journal, Vol. 91, No. 5, pp. 537-551. DOI: https://doi.org/10.14359/4168
Rasmussen, B. H. (1963). “The Carrying Capacity of Transversely Loaded Bolts and Dowels Embedded in Concrete”. Bygningsstatiske Meddelser, Vol. 34, No. 2.
Rodriguez, M. and Park, R. (1991). “Repair and Strengthening of Reinforced Concrete Buildings for Seimic Resistance”. Earthquake Spectra, EERI, Vol. 7, No. 3, pp. 439-459. DOI: https://doi.org/10.1193/1.1585636
Rodriguez, M. and Park, R. (1994). “Seismic Load Tests of Reinforced Concrete Columns Strengthened by Jacketing ”. ACI Structural Journal, Vol. 91, No. 2, pp. 150-159.
Rodriguez, M. E. and Santiago, S. A. (1998). “Simulated Seismic Load Tests on Two Story Waffle Flat Plate Structure Rehabilitated by Jacketing”. ACI Structural Journal, Vol. 95, No. 2, pp. 129-141.
Stoppenhagen, D. R, Jirsa, J. O. and Wyllie, L. A. (1995). “Seismic Repair and Strengthening of a Severely Damaged Concrete Frame”. ACI Structural Journal, Vol. 92, No. 2, pp. 177-187.
Tassios, T. P. (1983). “Physical and Mathematical Models for Redesign of Damaged Structures”. Proceedings of the IABSE Symposium: Strengthening of Building Structures Diagnosis and Therapy, Venice, pp. 30-52.
Tassios, T. P. (2004). Postgraduate studies course notes on: Theory for design of repaired and strengthened structures. School of Civil Engineering, National Technical University of Athens, Athens, Greece. (In Greek).
Tassios, T. P. (2005). Personal communication.
Tsioulou, O. T. and Dritsos S. E. (2006). “An Analytical Procedure for RC Beams Strengthened by New Concrete Layers”. Proceedings of the 11th International Conference on Structural Faults and Repair, Edinburgh. CD Proceedings.
Tsonos, A. G. (2004). “Effectiveness of CFRP-Jackets and RC-Jackets in Post-Earthquake and Pre-Eartquake Retrofitting of Beam-Column Subassembages”. Proceedings of the 13th World Conference on Earthquake Engineering, Vancouver, B.C., Canada, August 1-6, Paper No. 2558.
Tsoukantas S. G. and Tassios T. P. (1989). “Shear Resistance of Connections between Reinforced Concrete Linear Elements”. ACI Structural Journal, Vol. 86, No. 3, pp. 242–249.
Vandoros, K. G. and Dritsos, S. E. (2006a). “Axial Preloading Effects when Reinforced Concrete Columns are Strengthened by Concrete Jackets”. Progress in Structural Engineering and Materials, Vol. 8, pp. 78–92. DOI: https://doi.org/10.1002/pse.215
Vandoros, K. G. and Dritsos, S. E. (2006b). “Interface Treatment in Shotcrete Jacketing of Reinforced Concrete Columns to Improve Seismic Performance”. Structural Engineering and Mechanics Journal, Vol. 23, No. 1, pp. 43–61. DOI: https://doi.org/10.12989/sem.2006.23.1.043
Vandoros, K. G. and Dritsos, S. E. (2006c). “Concrete Jacket Construction Detail Effectiveness when Strengthening RC Columns. ” Journal of Construction and Building Materials. (In print).
Vassiliou, G. (1975). “An Investigation of the Behaviour of Repaired RC Elements Subjected to Bending”. PhD Thesis. National Technical University of Athens, Greece. (In Greek).
Vintzileou, E. N. and Tassios, T. P. (1986). “Mathematical Models for Dowel Action under Monotonic and Cyclic Conditions”. Magazine of Concrete Research, Vol. 38, No. 134, pp. 13-22. DOI: https://doi.org/10.1680/macr.1986.38.134.13
