Keywords: non-linear analysis, steel structures, web openings, steel design and behaviours, finite element method.

Height limitations are frequent in multi-storey buildings due to zoning regulations, economic requirements and esthetic considerations. High spaces are normally required to enable the passage of large pipes and ducts beneath steel beams leading to uneconomic floor heights. Various solutions can be used to overcome these problems, for example tapered and haunched beams, stub girders and composite trusses. Despite theses facts, the most adopted solution is the use of holes at the steel beam webs in order to enable the passage of services.

Chung et al. [1,3] and Chung and Lawson [2] stated that services that require web openings of up to 75% of the beam height are not uncommon. These openings could lead to a significant decrease of the beam load carrying capacity depending on the adopted holes shape, size and location.

This motivated the present investigation that used finite element simulations to quantitatively and qualitatively evaluate the structural behaviour of steel beams with web openings. The hole height usually controls the bending and shear collapse at the perforated sections. The hole width controls the Vierendeel failure that also depend on the local shear and bending resistances of the upper and lower "Tees".

These numerical models were calibrated against numerical investigation made by Chung et al. [1,3] and by experimental results performed by Redwood and Mccutcheon [4]. An additional finite element model of cellular beams with circular web opening was also made in the present investigation and later calibrated against the results of Bitar et al. [5].

The finite element method proved to be a valuable tool for evaluating and predicting the structural response of steel beams with web openings. The method proved to be reliable for estimating stress distributions, collapse load magnitude and associated failure modes. The comparisons between the finite element predictions and the experimental results for the cellular beam model were good in terms of failure modes (Vierendeel mechanism) and ultimate loads.

1

Chung K.F., Liu T.C.H. and Ko A.C.H., "Investigation on Vierendeel mechanism in steel beams with circular web openings", Journal of Constructional Steel Research, 57(5), pp. 467-490, 2001. doi:10.1016/S0143-974X(00)00035-3

2

Chung K.F. and Lawson R.M., "Simplified design of composite beams with large web openings to Eurocode 4", J. of Constructional Steel Research, Elsevier, pp. 135-163, 2001. doi:10.1016/S0143-974X(00)00011-0

3

Chung K.F., Liu T.C.H. and Ko A.C.H., "Steel beams with large web openings of various shapes and sizes: an empirical design method using a generalised moment-shear interaction curve", Journal of Constructional Steel Research, 59(9), pp. 1177-1200, 2003. doi:10.1016/S0143-974X(03)00029-4

4

Redwood R.G. and Mccutcheon J.O., "Beam tests with un-reinforced web openings", J. Structural Division, ASCE, 94(1), pp.1-17, 1968.

5

Bitar D., DeMarco T., Martin P.O., "Steel and composite cellular beams - Novel approach for design based on experimental studies and numerical investigations", Eurosteel 2005, 4th European Conf. on Steel and Composite Structures, Maastricht, v. B, p. 1.10.1-1.10.8, 2005.

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