Effect of Debonding of Rebars on the Seismic Response of Boundary Elements of Lightly Reinforced Shear Walls

Document Type: Regular Paper

Authors

Department of Civil Engineering, Faculty of Engineering, Urmia University, Urmia, Iran

10.22075/jrce.2020.19626.1375

Abstract

Rebar fracture in boundary elements of lightly reinforced shear walls in recent earthquakes motivated research on the minimum longitudinal reinforcement of shear walls. These researches lead to change in the ACI 318-19 requirement for minimum longitudinal reinforcement of boundary elements. New ACI 318 requirement increases minimum longitudinal reinforcement ratio for boundary elements of shear walls with low demand, that could have economic burden. This study experimentally investigates is it possible to avoid this increase in minimum rebar by debonding rebars in critical region of boundary elements in lightly reinforced shear walls. Tests includes specimens with bonded and debonded rebars, which are tested under monotonic and cyclic loading. Load protocol to account for failure types of low reinforcement shear walls is asymmetric.  Test results show that out of plane buckling of specimens with debonded rebars initiates at lower axial strains that could be attributed to reduction in element lateral stiffness due to use of debonding. On the other hand debonding resulted in reduction of local strain demand on rebar. It could be concluded that larger minimum dimension for boundary elements will be required when debonding is employed.

Keywords


Eligehausen, R., Ozbolt, J., Mayer, U. (1998). “Contribution of concrete between cracks at inelastic steel strains and conclusion for the optimization of bond, Bond and development of reinforcement.” SP 180, American Concrete Institute, Farmington Hills, MI, pp. 45-80.
Collins, M.P., Mitchell, D. (1990). “Prestressed Concrete Structures.” Prentice-Hall Inc., Englewood Cliffs, NJ, 766 p.
Mohle, J. (2015). “Seismic Design of Reinforced Concrete Buildings.” McGraw-Hill, 760 p.
CEB-FIP. (2007). “Bulletin 39: Seismic Bridge Design and Retrofit – Structural Solutions, International Federation for Structural Concrete”, Lausanne, Swiss.
ACI 318-19. (2019). “Building code requirements for structural concrete (ACI 318-19) and commentary.” American Concrete Institute, Farmington Hills, MI.
Lu, Y., Henri, R.S., Ma, Q.T. (2014). “Numerical modelling and testing of concrete walls with minimum vertical reinforcement.” NZSEE conference.
Arteta, C.A., To, D.V., Moehle, J.P. (2014). “Experimental response of boundary elements of code-compliant reinforced concrete shear walls.” Tenth U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering, Anchorage, Alaska.
Cook, D.T., To, D., Moehle, J. (2012). “Ductility of RC shear wall boundary element in compression.” PEER Internship Program.
Sritharan, S., Beyer, K., Henry, R.S., Chai, Y.H., Kowalsky, M., Bullf, D. (2014). “Understanding Poor Seismic Performance of Concrete Walls and Design Implications.” Earthquake Spectra, Vol. 30, Issue 1, pp. 307-334, doi:10.1193/021713EQS036M.
Hoult, R.D., Goldsworthy, H.M., Lumantana, E. (2016). “Displacement capacity of lightly reinforced rectangular concrete walls.” Australian Earthquake Engineering Society 2016 Conference, Melbourne, Victoria.
Hoult, R.D., Goldsworthy, H.M., Lumantana, E. (2016). “Seismic Performance of lightly reinforced and unconfined C-saped walls.” Australian Earthquake Engineering Society 2017 Conference, Canberra, ACT.
Lu, Y., Henry, R.S., Gultom, R., Ma, Q.T. (2017 ). “Cyclic testing of reinforced concrete walls with distributed minimum vertical reinforcement.” ASCE Journal of Structural Engineering, Vol. 143, Issue 5, doi:10.1061/(ASCE)ST.1943-541X.0001723.
NZS 3101 (2006 ). “Concrete structures standard (Amendment 3).” Wellington, New Zealand.
Shimazaki, K. (2004). “De-Bonded Diagonally Reinforced Beam for Good Repairability.” 13th World Conference on Earthquake Engineering, Vancouver, B.C., Canada, Paper No. 3173.
Patel, V.J., , Van, B.C., Henry, R.S., Clifton, G.C. (2015). “Effect of reinforcing steel bond on the cracking behaviour of lightly reinforced concrete members.” Construction and Building Materials, Vol. 96, Issue 2, pp. 238–247, doi.org/10.1016/j.conbuildmat.2015.08.014.
Paulay, T., and Priestley, M. J. N., (1993). “Stability of ductile structural walls.” ACI Structural Journal, Vol. 90, Issue 4, pp. 385–392.
Rosso, A., Jimenez-Roa, L.A., Almeida, J.P., Blando, C.A., Bonett, R.L., Beyer, K. (2018). “Cyclic tensile-compressive tests on thin concrete boundary elements with a single layer of reinforcement prone to out-of-plane instability.” Bulletin of Earthquake Engineering, Vol. 16, Issue 2, pp. 859-887, doi:10.1007/s10518-017-0228-1.
Haro, A.G., Kowalsky, M., Chai, Y.H., Luciera, G.W. (2018). “Boundary Elements of Special Reinforced Concrete Walls Tested under Different Loading Paths.” Earthquake Spectra, Vol. 34, Issue 3, pp. 1267-1288, doi:10.1193/081617EQS160M.
Altheeb, A., Albidah, A., Lam, N.T.K., Wilson, J. (2013). “The development of strain penetration in lightly reinforced concrete shear walls.”, Australian Earthquake Engineering Society 2013, Hobart, Tasmania.
Sezen, H., Setzler, E.J. (2008). “Reinforcement slip in reinforced concrete column.” ACI Structural Journal, Vol. 105, Issue 3, 280-288.
Mander, J.B., Priestley, M.J.N., Park, R. (1984). “Seismic design of bridge piers.” Report 84-02, Department of Civil Engineering, University of Canterbury, Christchurch, New Zealand.
Hilson, C.W., Segura, C.L., Wallace, J.W. (2014). “Experimental study of longitudinal reinforcement buckling in reinforced concrete structural wall boundary element.” Tenth U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering, Anchorage Alaska.