'CAGE-LIKE' STEEL REINFORCEMENT IN SEISMIC PERFORMANCE OF REINFORCED CONCRETE ELEMENTS OF LOW ASPECT RATIO

摘要

In technical literature there is abundant information about the importance of the so-called "truss mechanism" in the strength of reinforced concrete elements with aspect ratio close to unity (length/height ≈1), such as squat shear walls and beam-column joints; however, little attention has been paid to the damage distribution and stress re-distribution associated with this mechanism. The aim of this paper is to analyze the influence of "cage-like" steel reinforcement in the seismic behavior of reinforced concrete elements with aspect ratio close to unity. Cage-like reinforcement is defined as those in which the steel rebars are distributed uniformly in the horizontal and vertical directions forming a grid. The results obtained in tests performed at the Instituto de Materiales y Modelos Estructurales of the Universidad Central de Venezuela (IMME-UCV) on four reinforced and unreinforced concrete elements under diagonal compression, two reinforced concrete shear walls and two reinforced masonry shear walls under lateral alternating loads are presented and discussed. A numerical model based on strut-and-tie model was developed with the aid of the commercial program SAP2000. The model allows us to evaluate the behavior of reinforced concrete elements with aspect ratio close to unity when subjected to pushover analysis until failure. The model considers the non-linear behavior of steel and concrete. The experimental and numerical results show that the cage-like reinforcement allows a better damage distribution, a better stress re-distribution and the improvement of the seismic performance of reinforced concrete elements with aspect ratio close to unity.