Journal of Earthquake Engineering, 16:188–210, 2012 Copyright © A. S. Elnashai & N. N. Ambraseys ISSN: 1363-2469 print / 1559-808X online DOI: 10.1080/13632469.2011.597485 Plastic Hinge Length Considering Shear Reversal in Reinforced Concrete Elements ABDELSAMIE ELMENSHAWI 1 , TOM BROWN 2 , and SALAH EL-METWALLY 1 1 Department of Structural Engineering, Mansoura University, Mansoura, Egypt 2 Department of Civil Engineering, Schulich School of Engineering, University of Calgary, Calgary, Alberta, Canada Concrete structures can dissipate seismic energy during moderate to severe earthquakes by deform- ing inelastically. The inelastic deformation should concentrate at specific locations, referred to as plastic hinges. An experimental program was conducted to explore the factors affecting plas- tic hinge formation and length in beams. The test variables included the concrete compressive strength, bottom/top reinforcement ratio, shear strength, and shear demand. The increase in concrete strength did not influence the plastic hinge length, which was increased significantly by the effect of shear spread. The shear spread depended on the shear strength/demand ratio and was predicted successfully by the analytical model proposed. Keywords Plastic Hinge; Shear Demand; Curvature; Seismic Design 1. Introduction A successful seismic design of a structure depends on the structure’s ability to dissipate earthquake-input energy. There are many mechanisms by which a structure can dissipate the earthquake-induced forces. Of these mechanisms, formation of the so-called plastic hinges, if they are designed properly, is one effective mechanism. The lateral strength of a structure can be fully achieved as designed, if the structure is able to form a beam mechanism. In this mechanism, the inelastic deformations are concentrated at the beam ends and the column ends of the first story (column base). These locations are identified as the plastic hinges. The formation of the plastic hinges at the ends of columns of a middle story can lead to a column or soft story mechanism. The latter mechanisms will increase and concentrate the rotational demand in one story vs. the former beam mechanism that distributes the rotational demand throughout the structure. In addition, the column mechanism can cause instability in the building and negatively affect the gravity resisting mechanism. Moreover, the rotational capacity associated with the column mechanism is usually much smaller than the rotational capacity associated with the beam mechanism. Prediction of the inelastic capacity and drift for an element or a structure depends on the length over which the inelastic deformation will occur (plastic hinge length). In general, there are many factors that can affect plastic hinge length including post-yield characteristics of the reinforcement, moment-shear interaction, and element Received 4 January 2010; accepted 12 June 2011 Address correspondence to Abdelsamie Elmenshawi, Department of Structural Engineering, Faculty of Engineering, Mansoura University, Mansoura, 35516, Egypt; E-mail: samie@mans.edu.eg 188