ArcelorMittal Europe - Long products Sections and Merchant Bars ACB® and Angelina® beams A new generation of beams with large web openings

Exposed cellular beams in a roof application at a motorway services

ACB® and Angelina® beams, with their circular and sinusoidal large web openings, elegantly combine function with flexibility. Alternatives to trusses and open-web joist systems, cellular beams are lightweight, long-spanning, structural elements that enable the design of vast column-free spaces. They can be used in composite and non-composite systems. Information includes analysis recommendations for use of these elements in traditional applications, such as floors and roofs; assumptions when considering how the sections will behave in response to fire; and information about using cellular beams...

 Technical fabrication Cellular ACB® and Angelina® beams are manufactured from standard hot-rolled steel sections. The length of the beam is established based from the framing layout. Dimensions that define the shape and layout of the openings – i.e. a0 (opening, depth), s (length of sinusoidal curve), and w (length of the intermediate web post) – are governed by strength and serviceability requirements and will be verified by the designer. ACB® - Cellular beam with circular large web openings Angelina® - Beam with sinusoidal large web openings total beam height T-section height at opening diameter...

2.1. Roof support systems 2.2. Floor support systems ACB® and Angelina® beams are an attractive solution in roof applications as they provide the functionality of trusses with one simple, prefabricated element. When used as long span roof members cellular beams are economical for spans of 20m and above, and have successfully been used for spans in excess of 40m. They can be used as simply supported members, cantilever elements or as part of moment or portal frame structures. Modern construction increasingly demands accommodation of building services (heating, ventilation, air conditioning, etc.)...

Studios d'Architecture ORY & Associés Figure 4: Renovation using ACB® beams at headquarters of Crédit Lyonnais, Paris 2.3. Specialty applications 2.3.1. Building renovations and adaptive reuse ACB® and Angelina® beams are often employed in the renovation and adaptive reuse of existing structures (Fig. 4). With their perforations, they fit in beautifully to such buildings and help to preserve architecture, openness and flexibility of the spaces. often dark spaces. In addition, the openings facilitate smoke evacuation and improved air circulation between sections. Cellular beams can be cambered...

3. Design and fabrication Flame cutting of hot rolled sections ACB® and Angelina® beams are fabricated exclusively using hot-rolled structural sections. The fabrication shop is located close to the ArcelorMittal Differdange (Luxembourg) heavy section rolling mill. The close proximity of these two sites limits transport, maximises responsiveness and minimises manufacturing costs. Fabrication of ACB® and Angelina® beams, is described below and illustrated in Fig. 6: A double (ACB®) or single (Angelina®) cut following a specified path is made in the web through flame cutting. The two resulting T-sections...

Figure 7: Fabrication of Angelina® beams 3.1. Determination of size and spacing of openings For a given section, there are endless combinations of opening sizes and spacing that can be implemented. Items that are typically considered when determining the appropriate layout for a project follow: • To maintain aesthetic proportions, the ratio between the opening height (a0), spacing (e) and final height (Ht) should be kept in a specific range. The range is generally governed by the application in which the system will be used (Fig. 8). In some cases, opening height (a0) is governed by the size...

Cellular beams spanning 25 meters and featuring important camber 3.2. Customisation of cellular beams 3.2.1. Curving or cambering Where required for architectural or serviceability reasons (i.e. create positive roof slopes for rainwater run off or to manage dead load deflection, cellular beams can be curved and cambered. Achieved during fabrication, the top and bottom tee’s are curved/cambered prior to assembly and welding into the final state (Fig. 9). A minimum camber of 15 mm is recommended, and in order to avoid any risk of inverted installation, cambers will be clearly marked on each beam...

Figure 11: Asymmetrical ACB® beam 3.2.3. Asymmetrical sections Top and bottom T from differing profiles, or even steel grades, can be welded together to produce asymmetric profiles (Fig. 11). Asymmetric beams are adapted to composite design, having the ideal distribution of mass resulting in the lightest possible section. For such systems, it is common to have a heavier bottom T as it is subject to tension from global bending. The top T's primary function is to support the wet concrete at the construction stage, and so this is typically 30% lighter than the bottom T. 3.2.4. Elongated openings...

ACB® beam featuring filled openings at support 3.2.7. Web reinforcement Serviceability limit states require sufficient stiffness to reduce deflection and minimise vibrations. Cellular beams can efficiently meet these needs by optimising the distribution of steel throughout the profile. At times, optimisation may result in a risk of buckling at one or two web posts near the supports. In order to fortify the section, the following options can be considered: • selection of a heavier section • use of a higher steel grade, which would increase the load bearing capacity of the web posts • infilling...

Select examples of fabrication options are shown in Figure 16. When designing the framework, special care should be given to the positions of the openings in order to avoid unnecessary filling (Fig. 17). Figure 16: Fabrication options delivered “as fabricated” and overlength • The first step is to optimise the beam from a structural point of view. • The second step is to adjust the spacing between openings so as to have a complete web post at the ends of the beam. delivered “as is”, overlength and with filled openings Figure 17: Optimisation of openings layout 1/2 disc Full disc delivered cut...