Evolutionary Modeling to Evaluate the Shear Behavior of Circular Reinforced Concrete Columns

Despite their frequent occurrence in practice, only limited studies on the shear behavior of reinforced concrete (RC) circular members are available in the literature. Such studies are based on poor assumptions about the physical model, often resulting in being too conservative, as well as technical codes that essentially propose empirical conversion rules. On this topic in this paper, an evolutionary approach named EPR is used to create a structured polynomial model for predicting the shear strength of circular sections. The adopted technique is an evolutionary data mining methodology that generates a transparent and structured representation of the behavior of a system directly from experimental data. In this study experimental data of 61 RC circular columns, as reported in the technical literature, are used to develop the EPR models. As final result, physically consistent shear strength models for circular columns are obtained, to be used in different design situations. The proposed formulations are compared with models available from building codes and literature expressions, showing that EPR technique is capable of capturing and predicting the shear behavior of RC circular elements with very high accuracy. A parametric study is also carried out to evaluate the physical consistency of the proposed models. 1. Introduction It is well known that columns are the most vulnerable elements in reinforced concrete (RC) structures. These elements are principally designed to bear axial loads, but as a result of lateral loads, for example, wind pressure or earthquake ground motion, they could deal with relevant shear loads and thus should inevitably be designed to avoid possible shear failures [1–6]. Composite and steel columns [7] are particularly suitable at this aim. Circular columns are very popular for bridge pier design, due to simplicity of construction and because their strength characteristics under wind and seismic loads are similar in any direction. Circular elements are also used extensively as columns in buildings, or as piles for foundations, or as secant piling to form diaphragm walls. Despite their frequent occurrence in practice, only limited researches on the shear behavior of RC circular members have been carried out. Most of the researchers and codes state that the shear strength of a beam is the sum of the contributions of concrete and shear reinforcement , if present. The first takes into account the shear stress transferred by the compressed zone of the beam, the dowel action, the aggregate interlock, and the arch effect and depends on