Non Linear Behaviour of RCC Core Steel Composite Column

Abstract

In RCC core steel composite column the concrete and steel are combined in such a fashion that the advantages of both the materials are utilized effectively. The core steel composite column helps to improve the strength and ductility of column when compared to the ordinary reinforced concrete column. Core steel section is helpful in resisting column from large axial compressive force, bending moment, and shear failure. A materially nonlinear model is proposed using ANSYS software with proper boundary conditions. This paper presents nonlinear finite element analysis of concrete encased steel column subjected to reverse cyclic, buckling and monotonic loading condition and to understand maximum deformation, load it can withstand, and stress distribution. The result obtained from finite element analysis showing that the core steel composite column is a effective solution for seismic and non seismic areas. Core steel composite column shows large deformation capacity, lateral load resistance and stiffness. Keywords-RCC core steel composite column, RC column 1.INTRODUCTION Composite column are structural members composed of steel and concrete joined together to act as a single unit. The composite structural members are often used for medium-rise to high-rise buildings. Two types of composite columns frequently used in the buildings which are concrete-encased steel (core steel) columns and concrete filled steel tube columns [1]. The core steel composite column can be divided into two: fully encased core steel composite column and partially encased core steel composite column (Fig. 1). (a) (b) (c) (d) (e) Fig. 1: Different types of RCC Core steel composite column: a, b &c-fully encased composite column, d &e-partially encased composite column Steel and concrete are merged in such a fashion that the advantages of both the materials are utilized effectively in core steel composite column. In this type of column both the steel and concrete would resist the external loading by interacting together by bond and friction.A composite column is a combination of concrete, structural steel and reinforcing steel to provide an sufficient load carrying capacity of the member [2], increases its strength and stiffness, but also protects it from fire damages. Encased core steel makes the deformation capacity of the RC column to be large [3]. In core steel columns, the encased steel section can improve the shear resistance of the column [4]. To understand the behavior, several researches where conducted on core steel composite column. An analysis is conducted on concrete encased steel special shaped column (CESC) by providing combined axial and cyclic lateral loading and the results indicates that CESC column exhibits higher lateral bearing capacity and better seismic performances and are recommended to be widely applied to high rise buildings and in seismic prone areas[5]. To know more about core steel composite column an experimental study conducted on normal strength and high strength core steel composite column under monotonic and cyclic loading [6]. The result obtained showing that the column made with high strength concrete showed improved performance. The experimental results concrete-encased composite beam-columns with T-shaped steel section indicate that the behaviour of column under cyclic load and failure modes of the beam-columns are greatly affected by the direction of the bending moment due to the unsymmetrical cross section [7]. Pedro et al.,[8] conducted studies for concrete-encased I-shaped steel composite columns to investigate the axial load-carrying capacity, behaviour under uniaxial bending and axial compressive load, and behaviour under biaxial bending and axial compressive load. The composite structural member produced by inserting an additional steel section into the inside of the cross section takes the axial compressive force shows the best performance for the cyclic loading. The studies reveals that there are some factors which influence the performance of core steel composite column, which are axial compressive ratio, stirrup ratio and steel shape. These factors also affect seismic behaviour of composite column. A structural steel with H, I or cross-shaped steel section is generally used in an inner column of the composite building. As it shows better performance compared to other sections [9]. The behavior of column under fire is one of the main problems to be studied. Joao Paulo et