9416759 Sozen This project conducts a detailed evaluation of shear failures observed in bridge piers during the Northridge Earthquake. The primary objective of this study is to develop design and strengthening criteria for similar structures in regions of low to moderate seismicity. It is well known that many aspects of the shear strength of reinforced concrete elements are poorly understood. Applicability of existing design criteria are limited to the ranges of the variables involved in available experience and experiments. A reinterpretation of the available procedures and experimental data for shear strength are needed in the light of both positive and negative experiences during the Northridge event. Such a study is needed primarily because of observations that probable maximum unit shear stresses sustained by bridge piers failing in shear during the Northridge Earthquake were decisively less than measured unit shear strengths of comparable test specimens reported in the literature. Old as well as new hypotheses for shear strength will be evaluated in the light of (a) existing experimental data and (b) data from damaged and undamaged piers during the Northridge event. A set of design criteria applicable to similar structures in regions of low to moderate seismicity will be assembled on the results of this study. This is a Northridge Earthquake project. ***
