Keywords: finite element, numerical modeling, ANSYS, connections, fire, ISO 834 temperature-time curve.

The flush end-plate beam-to-column connection is an important structural system in steel structural design. It is commonly used in the construction of modern steel buildings. A typical flush end-plate connection consists of a rectangular steel plate nearly the beam depth and is welded to the beam-end. This assembly is connected to the flanges of a column by structural steel bolts. In the traditional steel structural design, the behaviour of beam-to-column connections was assumed to be either rigid or pinned and possess significant stiffness and strength at elevated temperatures. However, observation from the full-scale fire tests damaged structures [1,2] it has confirmed that the behaviour of beam-to-column connections used in actual structures exhibits a range of characteristics between the two extreme cases of fully rigid and ideally pinned [3]. The evidence from the collapse of the World Trade Center building [4] and full scale fire tests at Cardington [5] indicated that connections have a significant effect on the survival time of structures. Many experimental tests have been conducted in the last few decades to study the effect of both dynamic loads and service loads on flush end-plates, however, very little information on the behaviour of flush end-plates under fire conditions have been disseminated. In this research, the flush end-plate beam-to-column connections are investigated in fire conditions.

As a result of the high cost of experimental tests at elevated temperatures, a three-dimensional finite element analysis was conducted to study the behaviour of flush end-plate connections using the finite element software ANSYS. All the components of the connection were modelled by using solid elements, the contact element has been used for the contact surface to transfer the load from the beam to column. The finite element results were compared with experimental data. The results obtained showed good agreement both in elastic and plastic stages. The degradation of the connection stiffness and strength with increasing temperatures is well predicted by the model. This has demonstrated that the finite element technique is capable of predicting the connection response at elevated temperatures.

1

K.S. Al-Jabri, T. Lennon, I.W. Burgess, R.J. Plank, "Behaviour of steel and composite beam-column connections in fire", J Construct Steel Res, 46(1-3), paper 180, 1998. doi:10.1016/S0143-974X(98)00059-5

2

K.S. Al-Jabri, T. Lennon, I.W. Burgess, R.J. Plank, "The performance of frame connections in fire", ACTA Polytech, 39(5), 65-75, 1999.

3

W.F. Chen, E.M. Lui, "Stability design of steel frames", CRC Press, Inc., Boca Raton FL, USA, 1991.

4

NIST, "Final Report on the Collapse of the World Trade Center Towers", National Institute of Standards and Technology, USA, 2005.

5

G.M. Newman, J.T. Robinson, C.G. Bailey, "Fire safety design: A new approach to multi-storey steel-framed buildings", The Steel Construction Institute, 2004.

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