opennings in beams ec3_1

Scheme Development: Web openings for services in beams in multi-storey buildings SS015a-EN-EU

Scheme Development: Web openings for services in beams in multi-storey buildings

Outlines the types of openings in beams in multi-storey buildings that are necessary to accommodate service within the depth of the beam. Gives guidance on practical geometric limits.

Contents

1. Form of Construction 2

2. Geometric Limits on Opening Size 2

Scheme Development: Web openings for services in beams in multi-storey buildingsC

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1. Form of Construction Web openings may be used in cases where the beam is over-designed in bending, or where shear forces are relatively low. Three generic types cases of beams with web openings exist:

Cellular beams with multiple circular openings.

Castellated beams with multiple hexagonal openings.

Fabricated or hot rolled steel beam with isolated openings.

For cellular or castellated beams, it is generally the conditions of high shear close to the supports that control design, whereas for fabricated beams, both the cross-section and opening size can be ‘tailor made’ for the application.

Cellular beams are increasingly used because their openings are efficient for circular service ducts. Elongated openings, for rectangular ducts, can be created by removing the web-post locally in regions of low shear.

2. Geometric Limits on Opening Size Limits on the size of the openings for concept design of beams with large web openings are summarised in Table 2.1 and in Figure 2.1. Rectangular openings may be required at major service routes.

Particular care is required in cases of heavy point loads, or openings close to the supports. At secondary beam locations, vertical stiffeners may be required.


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Table 2.1 Geometric limits for large web openings

Dimensional limit

Circular Opening Rectangular Opening

Diameter / depth ≤ 0.8 D ≤ 0.7 D

Spacing ≥ 0.4 do ≥ Ro and ≥ do

End distance ≥ 0.5 do ≥ D

Distance from point loads ≥ 0.5 do ≥ D

D = depth of section do = opening diameter or depth Ro = length of opening

0 0

0

D

D

D

>0.5d

≥ R R>

R0.25≥ 0 0≤d 0.7 D

>0.4d 00

d 0.8 D≤

Figure 1.1 Limits on sizes and spacing of circular and rectangular web openings


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An example of a series of rectangular openings in a primary beam is shown in


Figure 2.2.

An example of an elongated opening in a cellular beam is shown in Figure 2.3.

Figure 2.2 Series of rectangular openings in a primary beam

Figure 2.3 Elongated openings in cellular beams


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Quality Record RESOURCE TITLE Scheme Development: Web openings for services in beams in multi-

storey buildings

Reference(s)

ORIGINAL DOCUMENT

Name Company Date

Created by R.M. Lawson SCI Jan 05

Technical content checked by G.W. Owens SCI May 05

Editorial content checked by D.C. Iles SCI May 05

Technical content endorsed by the following STEEL Partners:

1. UK G.W. Owens SCI 26/5/05

2. France A. Bureau CTICM 26/5/05

3. Sweden A. Olsson SBI 26/5/05

4. Germany C. Mueller RWTH 11/5/05

5. Spain J. Chica Labein 20/5/05

6. Luxembourg M. Haller PARE 26/5/05

Resource approved by Technical Coordinator

G.W. Owens SCI 26/4/06

TRANSLATED DOCUMENT

This Translation made and checked by

Translated resource approved by


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opennings in beams ec3_1

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