Post-earthquake reconnaissance and results of previously conducted experiments show thatudstiffness and strength deterioration of beam-column joints can have a detrimental effect on theudintegrity and vulnerability of reinforced concrete frame structures, especially in older buildingsudin developing countries. As a result, there is a need to develop efficient structural evaluationudtechniques that are capable of accurately estimating the strength and deformability of existingudbuildings to facilitate the development of safer, simpler, and lower cost retrofit solutions andudthus contributing to risk mitigation.udThe current research is part of a general effort that is being carried out at the University ofudSheffield to quantify and develop strategies for the mitigation of seismic risk in developingudcountries. The primary aim of this work is to improve the current understanding of the seismicudbehaviour of deficient exterior reinforce concrete beam-column joints. Seven full-scale isolatedudexterior beam-column joints were tested under quasi-static cyclic loading to investigate andudquantify the effects of using different types of beam reinforcement anchorages and low columnudaxial loads on the seismic shear performance of exterior beam-column joints with no shearudreinforcement.udContrary to what is reported in the literature, the test results show that increasing the columnudaxial load even at very low levels «O.2f'oAg,) can enhance the joint shear strength of deficientudexterior joints (exhibiting pure shear failure) by up to 15%. The test results also show that, forudthe same joint panel geometry and column axial load, the type of beam anchorage detail,udwhether it is a straight bar, long or short hook, can influence the joint shear strength by up toud34%.udA new analytical model that predicts the shear strength of deficient exterior beam-column jointsudin both loading directions and takes into account the column axial load and bond conditionsudwithin the joint is developed. The model predicts with good accuracy the strength of the testedudspecimens in addition to other specimens reported by other researchers. Furthermore, a springbasedudexterior beam-column joint model for finite element analysis of deficient RC frames isudproposed. The model development includes a joint shear stress-strain constitutive model basedudon the developed strength model. The simulated response using the proposed model shows goodudagreement with the experimentally observed response.
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