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Structural Engineering and Mechanics
  Volume 67, Number 1, July10 2018 , pages 001-8
DOI: https://doi.org/10.12989/sem.2018.67.1.001
 


Seismic performance of RC frames retrofitted with haunch technique
Junaid Akbar, Naveed Ahmad, Bashir Alam and Muhammad Ashraf

 
Abstract
    Shake table tests performed on five 1:3 reduced scale two story RC moment resisting frames having construction defects, have shown severe joint damageability in deficient RC frames, resulting in joint panels\' cover spalling and core concrete crushing. Haunch retrofitting technique was adopted herein to upgrade the seismic resistance of the deficient RC frames. Additional four deficient RC frames were built and retrofitted with steel haunch; both axially stiffer and deformable with energy dissipation, fixed to the beam-column connections to reduce shear demand on joint panels. The as-built and retrofitted frames\' seismic response parameters are calculated and compared to evaluate the viability of haunch retrofitting technique. The haunch retrofitting technique increased the lateral stiffness and strength of the structure, resulting in the increase of structure\'s overstrength. The retrofitting increased response modification factor R by 60% to 100%. Further, the input excitation PGA was correlated with the lateral roof displacement to derive structure response curve that have shown significant resistance of retrofitted models against input excitations. The technique can significantly enhance the seismic performance of deficient RC frames, particularly against the frequent and rare earthquake events, hence, promising for seismic risk mitigation.
 
Key Words
    seismic resistance; haunch retrofitting; shake-table; joint damage; response modification factor
 
Address
Junaid Akbar, Naveed Ahmad, Bashir Alam and Muhammad Ashraf: Department of Civil Engineering, Earthquake Engineering Center, UET Peshawar 25120 Khyber Pakhtunkhwa, Pakistan
 

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