Viktor Sigrist / IABSE Conference 2013, Rotterdam page 1/7 Assessment of Structural Concrete Members using the fib ModelCode 2010 Shear Provisions Viktor SIGRIST Professor Hamburg University of Technology Hamburg, Germany sigrist@tu-hamburg.de Viktor Sigrist, born 1960, received his civil engineering and doctoral degrees from ETH Zurich, Switzerland. He worked as a structural engineer in Switzerland before becoming Professor of concrete structures at the Hamburg University of Technology (TUHH), Germany, in 2002. Summary In this contribution the fib Model Code 2010 (MC10) shear provisions for members with shear reinforcement are outlined. Furthermore, they are compared to those of the Eurocode 2 (EC2). The Model Code developments comprise two novelties: These include the concept of the Levels of Approximation (LoA) and the dependence of the member's strength on its strain state. The idea behind MC10 is to have a solid basis for the design as well as the structural analysis of members in shear (assessment). Additionally, future developments should be enabled and a framework for this defined. In the comparison of the two codes it is shown that the results are partially in good agreement but deviate from each other in certain ranges of parameters. Keywords: assessment, concrete structures, design, ModelCode, shear 1. Introduction Current code provisions for shear in beams, i.e. members with shear reinforcement, are based on the so-called truss model concept. This holds true for the fib Model Code 1990 [1], Eurocode 2 [2], ACI 318 [3], CSA A23.3 [4] and others. However, over the years codes have diverged; depending on national conventions and research activities, one or another improvement and refinement has been included or added. Thus, for the development of the shear chapters of the new fib Model Code 2010 (MC10) [5] the following goals were identified: The provisions should be based on physical models (understandable), include the important influences (such as e.g. the strain dependence of the strength) and be open for future developments. Furthermore, it was agreed to introduce the Level of Approximation approach [6] as in engineering practice the assessment of structures significantly gains in importance and hence, more refined models are required. To achieve consistency within the code, the shear equations are further developed with reference to the well known approaches [7-11] and adjusted with help of a wide comparison with experimental data. One of the underlying ideas was to bring different design philosophies closer together by explicitly taking account of a concrete contribution to the shear resistance and creating a link between the analysis of members without and with shear reinforcement. As expected (and quite usual in code writing), not all aspects could be treated with the same thoroughness but overall, the equations given in the code yield good results and are more general and accurate as in any design code before. 2. General considerations For members with shear reinforcement the MC10 shear provisions are based on a general stress field approach [8,9,11]. As it is preferred in engineering practice, a cross sectional calculation procedure is outlined in the code. Such an analysis starts with the determination of the control section that quite often (as long as there is no abrupt change in the structure's geometry and the reinforcement layout) is located at a distance d from the face of the support, with d denoting the effective flexural depth of the beam (Fig. 1). The effective shear depth z can be taken as 0,9d.