Keywords: flush end plate, finite element, non-linear, composite joint, static loading, moment-rotation curve.

This paper aims to develop an accurate, well-defined finite element model to evaluate and to predict the behaviour of the semi-continuous composite connection with flush endplate under static loading. Investigations of the semi-continuous approach have been started a few years ago both on experimental and theoretical basis. In this research, the approach for developing a finite element model is different compared to some previous researchers using different element types.

Xiao et al. [1,2] have performed numerous large-scale experiments and developed comprehensive mathematical models to predict the behaviour of different types of composite connections. Ahmed and Nethercot [3] have carried out analytical studies with finite element method by using ABAQUS and proposed a method to calculate the initial stiffness of the flush endplate connections based on a simple force mechanism. Recently, Maggi et al. [4] studied parametric analyses of the behaviour of extended end plate connections using finite element modelling with solid and contact elements. But in this research shell, solid, 3D-spar and contact elements were used to develop the finite element models.

A finite element (FE) analysis programme ANSYS version 8.1, [5] was selected for the development and the analysis of the three-dimensional finite element models. In order to evaluate the capability of the three-dimensional finite element models, together with a study of the behaviour of the connection, the experimental program reported by Xiao et al. [1] was examined analytically. To achieve the accurate finite element models, the bare-steel joint was initially modelled with hexagonal bolt holes and finally refined with circular bolt holes considering practical situations. The moment-rotation curve and the stresses of both cases are compared and found to vary by only 5 to 7%.

To make a direct comparison between the analytical and experimental studies, the results of the finite element analysis of the connections are expressed in terms of their moment versus rotations. The results of finite element model and the experimental investigation of SCJ4 and SCJ5 are in fairly good correlation with each other with marginal differences of between 5 to 10%. Also different parameters have been studied and the moment-rotation curve for each case have been evaluated. It is observed that if the thickness of the endplate is higher than the thickness of the column flange, the moment capacity of the connection will not increase to a higher order due to excessive deformation of column flange and web. Waiving of column web stiffeners is not advisable because their absence causes premature failure in the column web. This consequently leads to a drastic drop in moment and rotation capacities.

From the results it is concluded that the finite element model is well constructed and seems to be adequate and in good agreement with the experimental results. Confidence in the FE model is a result of the excellent level of detailing done to accurately reproduce the actual geometry of all the structural components as prescribed by the experimental setup. The considerations given to the level and location of the mesh refinement is adequate and contributed to the good agreement of the results obtained. Special attention is given to the description of the boundary conditions to simulate the experimental setup.

This work clearly demonstrates that if a proper FE model is constructed as presented in this research, many advantages can be achieved such as tremendous savings in time and cost. The FE model gives flexibility to model different geometries and setups under a variety of loading conditions and different parameters. The FE analysis provides a full field of results that enables the investigator to view results at any location with ease.

1

Y. Xiao, B.S. Choo & D.A. Nethercot, "Composite Connections in Steel and Concrete. Part1-Experimental behaviour of composite beam-column connections", Journal of Constructional Steel Research, 31(l), 3-30, 1994. doi:10.1016/0143-974X(94)90021-3

2

Y. Xiao, B.S. Choo & D.A. Nethercot, "Composite Connections in Steel and Concrete. Part2 - Moment capacity of end plate beam to column Connections", Journal of Constructional Steel Research, 37(l), 63-90, 1996. doi:10.1016/0143-974X(95)00015-N

3

B. Ahmed, D.A. Nethercot, "Prediction of initial stiffness and available rotation capacity of major axis composite flush end plate connection", Journal of Constructional Steel Research, 41, 31-60, 1997. doi:10.1016/S0143-974X(96)00053-3

4

Y.I. Maggi, R.M. Goncalves, R.T. Leon & L.F.L. Ribeiro, "Parametric analysis of steel and bolted end plate connections using finite element modelling", Journal of Constructional Steel Research, 61, 689-708, 2005. doi:10.1016/j.jcsr.2004.12.001

5

ANSYS reference, "Release 8.1", ANSYS Incorporation, Canonsburg, 1999.

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