Reinforced concrete (RC) buildings designed before the mid-1970s may have serious structural deficiencies and are considered substandard according to current seismic design criteria. Specifically, the failure of the beam-column joints has been the cause of building collapse in many recent earthquakes worldwide. This report evaluates the seismic performance of beam-column joints with three different details of beam and beam-column joint reinforcement. A total of six
full-scale RC exterior joints were tested and their performance was examined in terms of lateral load capacity, drift, plastic rotation, joint shear strength, ductility, residual strength, and other PEER-established performance criteria. Two levels of axial compression load in the columns were investigated, and their influence on the performance of the joint is discussed. Performance levels for two types of failure mechanisms are established and comparisons are made to FEMA 273, FEMA 356, and ACI 352. In addition, the bond-slip behavior of the bottom beam bars is discussed. Limit states models are created and new modeli ng criteria for exterior joints with substandard details are proposed. Finally, a strut-and-tie model is developed for verifying the experimental results.
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