Ductility Enhancement in Reinforced Concrete Structure with Buckling Restrained Braced Frames

Abstract:

Adding braces to moment frames is considered to be quite an efficient technique for increasing the global stiffness and strength of the structure. It has not only been used in steel moment frames, but also in reinforced concrete (RC) moment frames in recent years. It certainly can increase the energy absorption capacity of structures and also decrease the demand imposed by seismic ground motions. Steel braces are anchored firmly to boundary beams and columns. They are modeled as truss elements and increase earthquake resistance of the building. Buckling restrained braced frames (BRBFs) in which members yield under both tension and compression without significant buckling have been used in recent years in order to ensure the desired seismic performance of special concentrically braced frames. BRBFs are similar to the special concentrically braced frames in that seismic accelerations are resisted by a building-frame members and diagonal braces whereas the design procedure is different. BRBs should be designed to permit ductile yielding both in compression and tension. In this paper, flat-slab RC building with two different configurations of buckling restraint braces (BRBs) is studied. The buildings have 4-storey with 5 bays in both X-and Y-directions and have been designed according to Turkish Specification of Reinforced Concrete Design (TS 500). In order to explore overall behavior up to failure and lateral load resisting capacities for these buildings, nonlinear static analyses have then been performed using SAP 2000-V14.1. Pushover analysis under constant gravity loads and monotonically increasing lateral forces during an earthquake until a target displacement is reached is generally carried out as an effective tool for performance based design. The major outcome of a pushover analysis is the capacity curve which shows the base shear vs. the roof displacement relationship and represents the overall performance of the building. The results of the analyses are presented in terms of capacity curve and energy dissipation.

References

[1] KHAMPANIT, A., LEELATAVIWAT, S., KOCHANIN, J., PENNUNG, W., Energy-based seismic strengthening design of non-ductile reinforced concrete frames using buckling-restrained braces, Engineering Structures, Vol. 81, 2014, pp.110-122.

DOI: 10.1016/j.engstruct.2014.09.033

[2] VISWANATH, K.G., PRAKASH K.B., ANANT DESAI, A., Seismic analysis of steel braced reinforced concrete frames, International Journal of Civil and Structural Engineering, Vol. 1, No. 1, 2010, pp.114-122.

[3] GOEL, S.C., LEE, H.S., Seismic strengthening of RC structures by ductile steel bracing system, Proceedings of Fourth U. S National Conference on Earthquake Engineering, Vol. 3 , 1990, pp.323-331.

[4] PINCHEIRA, J.A., JIRSA, J.O., Seismic response of RC frames retrofitted with steel braces or walls, Journal of Structural Engineering, Vol. 121, No. 8, 1995, pp.1225-1235.

DOI: 10.1061/(asce)0733-9445(1995)121:8(1225)

[5] NATEGHI, A. F., Seismic strengthening of eight-story RC apartment building using steel Braces, Engineering Structures, Vol. 17, No. 6, 1995, pp.455-461.

DOI: 10.1016/0141-0296(95)00071-e

[6] GHOBARAH, A., ABOUELFATH, H., Rehabilitation of reinforced concrete frame using eccentric steel bracing, Engineering Structures, Vol. 23, 2001, pp.79-104.

DOI: 10.1016/s0141-0296(00)00100-0

[7] MAHERI, M., SAHEBI A., Use of steel bracing in reinforced concrete frames, Engineering Structures, Vol. 19, No. 12, 1995, pp.1018-1024.

DOI: 10.1016/s0141-0296(97)00041-2

[8] IWATA, M., KATO, T., WADA, A., Buckling-restrained braces as hysteretic dampers, Proceedings of the Third International Conference on Behavior of Steel Structures in Seismic Areas (STESSA 2000), 2000, p.33–8.

DOI: 10.1201/9781003211198-6

[9] BLACK, C.J., MAKRIS, N., AIKEN, I.D., Component testing, seismic evaluation and characterization of buckling restrained braces, Journal of Structural Engineering, Vol. 130, No. 6, 2004, p.880–94.

DOI: 10.1061/(asce)0733-9445(2004)130:6(880)

[10] BERMAN, J.W., BRUNEAU, M., Cyclic testing of buckling restrained braced frame with unconstrained gusset connections, Journal of Structural Engineering, Vol. 135, No. 12, 2009, p.1499–510.

DOI: 10.1061/(asce)st.1943-541x.0000078

[11] THERMOU, G.E., ELNASHAI, A.S., Seismic retrofitting schemes for RC structures and local-global consequences, Progress in Structural Engineering and Materials, Vol. 8, No. 1, 2006, pp.1-15.

DOI: 10.1002/pse.208

[12] DI SARNO, L., CHIODI, R., MANFREDI, M., PROTA, A., Probabilistic assessment of seismic behaviour of an existing RC building retrofitted with BRBs, Safety, Reliability, Risk and Life-Cycle Performance of Structures & Infrastructures, 2013, pp.4129-4136.

DOI: 10.1201/b16387-599

[13] DI SARNO, L., MANFREDI, M., Experimental tests on full-scale RC unretrofitted frame and retrofitted with buckling-restrained braces, Earthquake Engineering and Structural Dynamics, 2012, pp.315-333.

DOI: 10.1002/eqe.1131

[14] ALBANESI, T., BERGAMI, A.V., NUTI, C., Design procedure for buckling restrained braces to retrofit existing RC frames, The Fourteenth World Conference on Earthquake Engineering, (2008).

[15] KHAMPANIT, A., LEELATAVIWAT, S., KOCHANIN, J., PENNUNG, W., Energy-based seismic strengthening design of non-ductile reinforced concrete frames using buckling-restrained braces, Engineering Structures, Vol. 81, 2014, pp.110-122.

DOI: 10.1016/j.engstruct.2014.09.033

[16] CHANDRA, J., WARNITCHAI, P., Application of buckling-restrained braces for seismic strengthening of irregular gravity load designed concrete frame buildings, Civil Engineering Dimension, Vol. 13, No. 2, 2011, pp.65-74.

DOI: 10.9744/ced.13.2.65-74

[17] TS 500, Turkish Reinforced Concrete Design Code, (2005).

[18] CLARK, P., AIKEN, I., KASAI, K., KO, E., and KIMURA, I. Design procedures for buildings incorporating hysteretic damping devices,. Proceedings of the 69th Annual Convention, (1999).

[19] WADA, A., SAEKI, E., TAKEUCHI, T., AND WATANABE, A., Development of Unbonded Brace", Nippon Steel, s Unbonded Braces (promotional document), pp.1-16, (1998).

[20] AISC 341, Seismic Provisions for Structural Steel Buildings, American Institute of Steel Construction, (2010).

DOI: 10.1201/b11248-16

[21] DORAN, B., AKBAŞ, B., ŞENOL, E., ŞEKER, O., Non-linear static analysis of strengthened existing RC frame building using steel braces, Vienna Congress on Recent Advances in Earthquake Engineering and Structural Dynamics, (2013).

[22] TSC-1997, Turkish Seismic Code, (1997).

[23] TSC-2007, Turkish Seismic Code, (2007).

[24] SAP 2000 v14. 1, Computers & Structures Inc., Berkeley, USA.

[25] FEMA 356, Federal Emergency Management Agency, (2000).