Determining Plastic Hinge Length of High Performance RC Beams

During earthquake concrete structures dissipate energy by deforming inelastically. The plastic deformation localized in a small zone namely the plastic hinge zone is critical for flexural members as it governs the load carrying and deformation capacities of the member. Pushover analysis, one method of nonlinear static analysis, is generally used in the assessment of existing buildings. Pushover analysis gives more realistic results when compared to linear analysis methods to achieve seismic performance level of structures. In pushover analysis nonlinear hinge properties of each member should be addressed. The formation of a plastic hinge in structural member depends on both the dynamic characteristic of earthquake and structural member properties such as dimension and material properties. Because of the difficulty and high complexity included, the behavior of plastic hinge of reinforced concrete flexural members has been previously investigated experimentally. Due to the high non-linearity occurs in plastic hinge zone and restrictions by the time and cost especially in large tests, very limited knowledge has been obtained up to date. Moreover past studies showed that none of the existing empirical models is adequate for prediction of plastic hinge length. This study tries to investigate the problem numerically using Nonlinear Finite Element Modeling (FEM) approach by employing software package ABAQUS. To achieve this, a numerical model is generated and verified with existing experimental studies obtained from the literature, by comparing load deflection response and rotational capacity of the test elements. Parametric studies are performed to investigate the plastic hinge length in terms of material properties concrete and dimensions of the member. High performance concrete is selected to be as C50, C60 and C80. With the calibrated FEM model, the extent of the rebar yielding zone and concrete crush zone are examined to define the plastic hinge length.