Original Research Article Novel non-invasive seismic upgradation strategies for gravity load designed exterior beam-column joints Ashok Kumar Kanchana Devi a,b, * , Ramajaneyulu Karusala a,b,1 , Mayank Tripathi b , Saptarshi Sasmal a,b,2 a CSIR-Structural Engineering Research Centre, Chennai 600113, Tamil Nadu, India b Academy of Scientific and Innovative Research (AcSIR), Taramani, Chennai 600113, Tamil Nadu, India 1. Introduction Prior to the introduction of modern seismic codes, the structures were designed to cater for gravity loads, i.e. the self-weight of the structural components and possible imposed vertical load acting on the structure. Hence, struc- tural components of GLD structures do not have adequate reinforcement to cater for the seismic forces. Further, joints of GLD buildings lack confinement, transverse reinforcement a r c h i v e s o f c i v i l a n d m e c h a n i c a l e n g i n e e r i n g 1 8 ( 2 0 1 8 ) 4 7 9 – 4 8 9 a r t i c l e i n f o Article history: Received 15 February 2017 Accepted 23 August 2017 Available online Keywords: Beam-column joint Upgradation Energy dissipation Strength degradation Reverse cyclic a b s t r a c t Existing gravity load designed (GLD) structures are vulnerable to seismic event due to their inherent weaknesses. The present study, focuses on the development of non-invasive and feasible strategies for seismic upgradation of these non-seismically designed structures. Three novel schemes, namely (i) single haunch upgradation scheme (U1), (ii) straight bar upgradation scheme (U2) and (iii) simple angle upgradation scheme (U3) are proposed for seismic upgrada- tion of GLD specimens. The efficacy and effectiveness of these upgradation schemes are evaluated by conducting the reverse cyclic load tests on control and upgraded GLD exterior beam-column sub-assemblages. The performance of the upgraded specimens is compared with that of the control GLD beam-column sub-assemblage, in terms of load–displacement hystereses, energy dissipation capacities and global strength degradation behaviour. Tremen- dous improvement in the energy dissipation capacity to the tune of 2.63, 2.83 and 1.54 times the energy dissipated by the control GLD specimen is observed in single haunch upgraded specimens, straight bar upgraded specimen and simple angle upgraded specimen respectively. The specimen with single haunch upgradation performed much better compared to the GLD specimens upgraded with the other two schemes, by preventing the brittle anchorage failure, delaying the joint shear damage and redirecting the damage partially towards the beam. © 2017 Politechnika Wroclawska. Published by Elsevier Sp. z o.o. All rights reserved. * Corresponding author at: Advanced Concrete Testing and Evaluation Laboratory, CSIR-SERC, Taramani, Chennai 600113, Tamil Nadu, India. E-mail addresses: kanchana@serc.res.in (A.K. Kanchana Devi), rams@serc.res.in (R. Karusala), tripathimayank93@gmail.com (M. Tripathi), saptarshi@serc.res.in (S. Sasmal). 1 Address: Advanced Concrete Testing and Evaluation Laboratory, CSIR-SERC, Taramani, Chennai 600113, Tamil Nadu, India. 2 Address: Bridge Engineering, CSIR-SERC, Taramani, Chennai 600113, Tamil Nadu, India. Available online at www.sciencedirect.com ScienceDirect journal homepage: http://www.elsevier.com/locate/acme http://dx.doi.org/10.1016/j.acme.2017.08.005 1644-9665/© 2017 Politechnika Wroclawska. Published by Elsevier Sp. z o.o. All rights reserved.