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A new £1 million 'Target Zero' project is looking at five major building types (schools, warehouses, offices, supermarkets and mixed use) and will generate fully-costed solutions demonstrating how to achieve the three highest BREEAM ratings and meet the changes to Part L of the Building Regulations.
With today’s structural steel framing, grace, art and function can come together in almost limitless ways; it offers new solutions and opportunities, allowing architects to stretch their imagination and actually create some of the most challenging structures they have designed in their minds. What was once thought impossible is now a reality. Structural steel’s low cost, strength, durability, design flexibility, adaptability and recyclability continue to make it the material of choice in building construction.
Structural steel has entered a new era. Today it provides not only strength to buildings, but also beauty and drama – enhancements which are difficult or too costly to produce with other materials.
Advanced steel fabrication technology has unfolded exciting architectural opportunities, allowing architects to expand their artistic expression and design spectacular structures with steel.
Curving and bending is now possible in ways that were never thought possible before. Depending upon the size and radius of the desired curve, beams can be bent up to 360 degrees. Curves using steel beams bent to a certain radius or segmented curves or combinations of both can create members that follow the outlines of irregular facades, arches or domes.
Today’s precision fabricating allows steel pieces to be combined in unprecedented ways. Special steel sections, unusual angles and detailing are now economically viable thanks to CAD programs and computer-controlled cutting, punching and welding.
Architects’ artistic freedom is further enhanced by the variety of steel shapes that can be worked with to perform special functions. Regardless of its shape, structural steel will carry required loads using a minimal amount of material. And, as building styles change, steel structures are easily re-designed by adding new facades or other architectural treatments.
Scaling down building height is important in controlling costs. Eliminating half a metre from each floor will cut the costs for steel and other building materials. From an energy-efficiency standpoint, minimising floor-to-floor heights also helps curb heating and cooling costs.
Running mechanical systems through web openings is one solution for minimising building heights. Another way is integrating floor beams into interior walls or partitions. Keeping the floor layout in mind takes careful planning but results in an efficient design.
In some cases, it is possible to limit the depth of beams by choosing a member size that is shallower, though heavier, yet still offers the same required strength. In the past, this was usually not economical, but with today’s relatively lower structural steel costs, it has become a reasonable solution.
“Slimflor” and the Asymmetric Beam provide exciting new alternatives. These both promote the opportunity to limit the depth of the floor to the depth of the beam and the thickness of the concrete cover over the decking.
Steel’s high strength-to-weight ratio enables it to span large distances gracefully and economically – more so than any other building material – in single storey buildings rolled beams can provide clear spans of over 50 metres, while using trussed or lattice construction can stretch this to more than 150 metres.
The long spanning capability of steel also enables the creation of large areas of unobstructed space in multi-storey buildings. While short to medium span steel systems will typically provide the lowest construction costs for the structural frame, many clients now demand the increased flexibility which only steel can provide with column spacings of 15 metres and more.
Steel transfer girders may bridge two points to create column-free spaces by eliminating columns. The Vierendeel truss, in particular, does not use any diagonal members, which can inhibit sight lines and traffic flow.
Fewer columns make it easier to subdivide and customise office space for current and future tenants. Open space also is more attractive to speculative buyers and commands a premium price in a competitive market.
In warehouses or manufacturing facilities, fewer columns means less restrictions on the location of fixed equipment, as well as fewer obstructions when operating forklifts and other material handling equipment. It is also much easier to accommodate a variety of industrial tenants’ floor-plan needs when an area has fewer columns.
Building owners often are faced with the challenge of modifying an existing space to meet changing needs – perhaps adding a new staircase, elevator or column-free space, or even raising or lowering a ceiling. Changes may also be necessary to comply with legislation such as the need to provide access for the disabled.
Steel is the only material that allows the strength of a structure to be increased economically once it is built. This is critical when a tenant would like to increase floor loads by adding such things as file storage, computer systems, mechanical units or hospital diagnostic equipment. Non-composite steel beams can be made composite with the existing floor slab or cover plates may be added to the beams for increased strength. Additional steel may also be bolted or welded to the existing steel framework. Beams and girders can be easily reinforced, supplemented with additional framing or even relocated to support changed loads.
Connections can be strengthened. These strategies may also be applied to industrial buildings, where increased loads can be created by changes in the manufacturing process or the installation of new equipment supported by the overhead framing.
Additionally, walls can be repositioned to accommodate new interior layouts based on changing traffic patterns and space usage. This is possible because the interior and exterior walls of steel-framed buildings are not load bearing.
Electrical wiring, computer networking cables and communication systems are also constantly being upgraded or modified in today’s high-tech offices. Steel framing and floor systems allow easy access to the wiring without disrupting the operations of the facility or the workers in the area.
Steel beams may include web openings for aesthetic or functional purposes while still allowing the beams to carry the required loads. This creates a light and airy appearance.
Piping and ductwork can pass through the beam openings instead of being housed in a separate layer above or below each floor. This helps reduce the overall height of a structure, resulting in material and operating cost savings.
Computer software is available that helps engineers determine how large openings can be, where they can be located and whether or not they need to be reinforced. Web openings can even be added at a later date if needed.
When designing a building in extreme wind or earthquake zones, the first concern is protecting the people who live and work in the structure. The second consideration is preserving the contents of the building, such as expensive computer systems or irreplaceable documents. The last, though still important, concern is the condition and reparability of the building.
Steel is the material of choice for design because it is inherently ductile and flexible. It naturally flexes under extreme loads rather than crushing or crumbling. Additionally, steel structures have reserve strength. Many of the beam-to-column connections in a building are designed to support vertical or gravity loads only. But they also have the capacity to resist lateral loads caused by wind and earthquakes. In their entirety, these connections provide considerable reserve strength not usually considered in the building design.
The speed at which a building is built is critical. Earlier occupancy means an office owner can begin renting space sooner, a factory owner can start producing products faster and the store operator can bring in sales pounds quicker.
Fast construction also lowers financing costs and overhead expenses for construction management services.
Because structural steel is lighter than other framing materials, it needs a smaller and simpler foundation. This reduces both cost and the time spent on construction.
Steel framing’s simple “stick” design allows construction to proceed rapidly from the start of erection. Once the frame and steel floor decking are in, other tradespeople can begin their work using the deck as a working surface. It is common for electricians and other trades to be well into their work before the concrete slab is put in place. Additionally, properly stabilised steel can be loaded immediately, enabling work to commence on the next level without delay.
Adverse weather conditions, unless extreme, do not impede the progress of steel erection. It is not necessary for additional inspection services, which cause further delays, because steel maintains its quality despite the weather.
Steel Buildings
Steel Detail
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