ABSTRACT
A large portion of existing reinforced concrete (RC) flat-plate buildings are seismically deficient and pose a risk of catastrophic failure if subjected to earthquakes of low to moderate intensity. Many of these buildings, pmticularly in the central and eastern parts of the United States, were only designed for gravity and wind loading and therefore do not have the lateral stiffness and proper connection detailing needed to withstand a seismic event ence from past earthquakes including the Fernando (Mahin et al. 1983), 1985 Mexico City (Meli & Rodriguez 1988) and others, clearly elucidates the potential for overwhelming damage and loss of life. The vulnerability of flat-plate buildings is mainly attributed to excessive lateral drift and punching shear failure at Lhe slab-column conneclion. In many instances, the lack of continuous reinforcement (particularly bottom reinforcement) through the joint has resulted in the progressive collapse of floors during moderate emthquakes. Laboratory tests have demonstrated that slab-column connections in existing non-ductile flat-plate buildings exhibit insufficient lateral stiffness and have a limited moment-transfer capacity (Durrani et al. 1995).
