Seismic behavior of beam-column joints strengthened with ultra-high performance fiber reinforced concrete

This paper presents a study on evaluation of seismic performance of shear-deficient beam column joints (BCJs) strengthened by ultra-high performance fiber reinforced concrete (UHPFRC). Normal concrete BCJs having deficiencies in resisting the seismic action were cast, strengthened with a thin layer of UHPFRC, and tested under seismic loading. Two different methods were used for strengthening the normal concrete BCJ specimens consisted of: i) sandblasting the normal concrete substrate surface of BCJs and in-situ casting of a 30 mm thick UHPFRC jacket and ii) bonding 30 mm thick prefabricated UHPFRC plates to seismically deficient BCJ using epoxy resins and special fillers. The performance of UHPFRC jacketing in strengthening the seismically deficient BCJs was experimentally evaluated under reverse cyclic loading using displacement control approach keeping column axial load constant at 150 kN. The analysis of test results showed that the first method of strengthening was highly effective in terms of shear capacity, deformation capacity, stiffness characteristics and energy dissipation capacity, as compared to the second method.