Parametric Study of steel-concrete composite beams
Abstract
In this paper a numerical model is developed to predict the behaviour of steel-concrete composite beams with circular openings up to failure. The numerical model takes into account both material and geometric non-linearity and nonlinear behavior of the connection. Calibration with experimental data obtained from previous work shows that the model is able to predict, with relatively good accuracy, the ultimate load. A parametric study is then followed to study the influence of post dimensions and the shape and spacing of the openings on the behavior of such beams under the action of three types of static loading
Keywords
Download Options
Introduction
Use of cellular composite beams is become very popular now a days due to its advantageous structural applications. Considering the high usage of cellular composite beams with web openings, particularly in high-rise buildings, study of their behavior is essential. Many investigations have been conducted regarding the behavior of these beams [1], [2], [3]. The information available on beams with web openings does not cover some points for circular openings. Different research studies are carried out for analysis and design of cellular steel beams with and without the presence of slab concrete. Ehab Ellobody [4] studied the interaction of buckling modes in castellated beam with hexagonal opening analytically as well as experimentally. 96 models of castellated beam were developed with all non linear material properties in ABAQUS Finite Element programming software. The parametric study was extended in order to study the effects on the beam when the geometries of the specimen is changed also the length of the beam was considered. It was observed that normal strength castellated beam generally fails in lateral torsional buckling, while high strength castellated beam fails by web distortional buckling. B. Anupriya and Dr. K. Jagadeesan [5] studied analytically shear strength and deflection properties of castellated beams with hexagonal openings using ANSYS14. Study shows that, as the depth of castellated beam increases, the stress concentration at corners as well as at the loading point increases. Konstantinos Daniel Tsavdaridis and Cedric D’Mello [6] studied the performance, modes of failure and the load carrying capacity of various types of cellular beams analytically as well experimentally, providing web openings at close spacing. Ehab Ellobody analyzed the castellated beam with circular openings by nonlinear analysis, where the combined modes of buckling of these beams were considered. The behavior was checked for high strength of beam by considering the parameters like imperfection of geometry, remaining stresses and also non linear material properties of material were considered. The non linear finite element method helped in predicting deflection, failure modes and also the loads causing failure. Wakchaure M.R. and al. [8] carried out experimental investigation on simply supported hexagonal castellated beam under two point loading. Modes of failure of the castellated were examined for different depths of openings. From the experimentation, researchers conclude that the castellated beam behaves satisfactorily up to a maximum depth of 0.6 times the depth of opening (0.6D). Siddheshwari. A. and al. [9] presented a review existing literature in which he explains the parameters that were considered and the numerical and experimental results.
The use of composite steel-concrete structures results in optimal performance of the two materials (the steel in tension and the concrete in compression) but in design process it is necessary to evaluate the influence of the connection between the two materials on the overall behavior of the structure. Consequently, slippage between the steel beam and the concrete slab cannot be neglected as suggested by the European Code of steel-concrete composite construction EC4 [10].
Conclusion
The modelization of the structural behavior of steel-concrete composite beams subjected to concentrated static load at midspan was developed in this study. The 3D numerical model presented here, allows provide a better understanding of the relationship between the slip and shear connectors. We can notice that the estimate of the deflection and curvature seems to be more influenced by the constitutive relations introduced to materials and shear connectors. The difference between the results of linear analysis and analysis by FEM can be explained by a misinterpretation of the connection behavior in the analytical method. As regards the sliping, the results show good agreement with the results of tests particularly for landslides at the end of the beam, with a difference of no more than 2.5% for the elastic limit load. When the failure load is reached, a good agreement between the curves "Moment-Curvature" is found, the registered difference is of the order of 17%.