Metal profiles

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Metal profile sheet systems are used to build cost efficient and reliable envelopes of mostly commercial buildings. They have evolved from the single skin metal cladding often associated with agricultural buildings to multi-layer systems for industrial and leisure application. As with most construction components, the ability of the cladding to satisfy its functional requirements is dependent on its correct specification and installation. Also important is its interaction with other elements of the building envelope and structure. Metal profile sheets are metal structural members that due to the fact they can have different profiles, with different heights and different thickness, engineers and architects can use them for a variety of buildings, from a simple industrial building to a high demand design building. Trapezoidal profiles are large metal structural members, which, thanks to the profiling and thickness, retain their high load bearing capability. They have been developed from the corrugated profile. The profile programme offered by specific manufacturers covers a total of approximately 60 profile shapes with different heights. Cassettes are components that are mainly used as the inner shell in dual-shell wall constructions. They are mainly used in walls today, even though they were originally designed for use in roofs.

Contents

History

Trapezoidal profiles and cassettes have been known in Europe for around 100 years. Today's characteristic profile shape came to Europe from the USA in the 50s and has gained relevance since about 1960. At present the proportion of load bearing, room sealing trapezoidal profiles used in the overall area of new and slightly sloping roofs amounts to 90%. Above all else the wide acceptance has resulted from the simple constructive training, fast assembly, and the low costs of the trapezoidal profile construction.

Specification of the metal profile

Weathertightness

The primary function of the cladding system is to provide a weathertight building envelope, suitable for the intended use of the building. Trapezoidal metal roof sheets with through fix fasteners are generally suitable for slopes of 4% or steeper. This limit is critical to the performance of the cladding. For shallower pitches, down to 1.5%, a fix system with no exposed through fasteners, special side laps and preferably no end laps should be used. For low pitch roof, ponding is a potential problem that must be considered at the design stage in order to avoid the deleterious effects of prolonged soaking and the increased loading, due to the weight of the water. [1]

Building appearance

Building envelope made from metal sheet provide builders and architects with products, which meet all of the highest demand regarding construction characteristics and design. The steel from which profiled cladding sheets are made is available pre-coated in a wide range of colors and textures, allowing architects to choose a finish that best suits the location and function of the building. Profile shape is also a characteristic that can be adapted to the demand of the architects. [2]

Thermal performance

Buildings are responsible of the 40% of European energy consumption, consequently, improving the thermal performance of the cladding and associated components is very important. The elemental U-value (thermal transmittance, W/m2K) of a cladding panel, depends on the conductivity and thickness of the insulation which is added, the profile shape and the presence of thermal bridges. So, metal profile sheets can achieve thermal performance regulations thanks of insulations and profile shape. It is very important to analyze and avoid all possible thermal bridges within the roof and wall cladding assembly, to minimize local heat/cold losses. [3]

Acoustics

Roofs constructed with trapezoidal profiles have excellent sound suppression characteristics. Sound has been found to be reduced to by up to 53 dB. The measured sound reduction for wall constructions using cassettes has been assessed at an RW of 57 dB. The acoustic performance of a particular cladding system will depend on the insulation material, the weather sheet and liner sheet profiles and the method of assembly. To minimize reverberation architects may take advantage of the sound absorbing properties of the cladding insulation layer by replacing the standard liner sheet with a perforated liner. [4]

Durability

In order to ensure that the building envelope remains fully functional throughout its design life, it is important that it receives regular maintenance, including inspection, removal of debris, cleaning and repair of damage. Inspection can include man-made or natural wear. Weather exposure, natural movement, installation error and manufacturing defects are examples. [5] The need of maintenance may be greatly reduced using specific coating depending on the weather conditions, this coating guarantee the expected design life of the cladding. The commonly used 302 stainless steel alone is resistant to acetic acid, acetone and boric acid, among others. [6] [7]

Sustainability

Metal profiles sheets have a high recycled scrap steel content and all steel is recyclable. Many steel components can be unbolted and even reused for future applications. The possibility of reusing building elements makes steel construction even more sustainable than the already significant contribution of today's simple material recycling. Steel can be repeatedly recycled because it does not lose any of its inherent physical properties as a result of the recycling process. Stainless steel fasteners have excellent corrosion resistance and durability, as well as being a sustainable material. Custom fasteners in this material make for the utmost of sustainability with high recyclability. [8] [9]

Structural performance

Metal cladding systems are required to carry externally applied loads, such as snow and wind loading without deflecting excessively or compromising the other performance requirements. The individual characteristic loads (actions) should be obtained from the appropriate part of EN 1991, taking into account the building geometry and location as applicable. These individual actions should then be combined using the appropriate safety factors from EN 1990 to obtain the load cases used in design. [10]

For most application of metal cladding technology, the only permanent action which the roof cladding needs to be designed is its own self-weight. For wall cladding, it is not normally necessary to consider permanent actions, since the self-weight acts in the plan of the cladding.

In addition to its self-weight, the roof cladding must also be designed for the following variable actions as specified in the appropriate parts of EN 1991: -Access for cleaning and maintenance. -A uniformly distributed load due to snow over the complete roof area. The value of this load will depend on the building's location. -Asymmetric snow load and loading due to snow drifts. -Wind loading due to pressure and suction.

Care must be taken on site to avoid excessive local deflection. Typical deflection limits imposed on the cladding are depend on the loading regime considered, the location of the structural component and whether a brittle material is present. Deflection limits may be specifies by National regulation. [11]

Main uses

Metal profile sheets due to their versatility mechanical and design properties can be used as roof and roof cladding, as external walls and wall cladding and also as floors. They are used in industry and in residential sector, and the two sectors can be used in both new construction and rehabilitation. Some of the applications where metal profile sheets are used are:

See also

Related Research Articles

Roof Top covering of a building

A roof is the top covering of a building, including all materials and constructions necessary to support it on the walls of the building or on uprights, providing protection against rain, snow, sunlight, extremes of temperature, and wind. A roof is part of the building envelope.

Earth shelter House partially or entirely surrounded by earth

An earth shelter, also called an earth house, earth bermed house, or underground house, is a structure with earth (soil) against the walls, on the roof, or that is entirely buried underground.

Structural insulated panel

A structural insulated panel, or structural insulating panel, (SIP), is a form of sandwich panel used in the construction industry.

Curtain wall (architecture) Outer non-structural walls of a building

A curtain wall is an outer covering of a building in which the outer walls are non-structural, utilized only to keep the weather out and the occupants in. Since the curtain wall is non-structural, it can be made of lightweight materials, such as glass, thereby potentially reducing construction costs. An additional advantage of glass is that natural light can penetrate deeper within the building. The curtain wall façade does not carry any structural load from the building other than its own dead load weight. The wall transfers lateral wind loads that are incident upon it to the main building structure through connections at floors or columns of the building. A curtain wall is designed to resist air and water infiltration, absorb sway induced by wind and seismic forces acting on the building, withstand wind loads, and support its own weight.

Concrete masonry unit Standard-sized block used in construction

A concrete masonry unit (CMU) is a standard-size rectangular block used in building construction. CMUs are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them.

This page is a list of construction topics.

Steel frame Building technique using skeleton frames of vertical steel columns

Steel frame is a building technique with a "skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The development of this technique made the construction of the skyscraper possible.

Formwork

Formwork is molds into which concrete or similar materials are either precast or cast-in-place. In the context of concrete construction, the falsework supports the shuttering molds. In specialty applications formwork may be permanently incorporated into the final structure, adding insulation or helping reinforce the finished structure.

A structural load or structural action is a force, deformation, or acceleration applied to structural elements. A load causes stress, deformation, and displacement in a structure. Structural analysis, a discipline in engineering, analyzes the effects of loads on structures and structural elements. Excess load may cause structural failure, so this should be considered and controlled during the design of a structure. Particular mechanical structures—such as aircraft, satellites, rockets, space stations, ships, and submarines—are subject to their own particular structural loads and actions. Engineers often evaluate structural loads based upon published regulations, contracts, or specifications. Accepted technical standards are used for acceptance testing and inspection.

Precast concrete Construction product produced by casting concrete in a reusable mold

Precast concrete is a construction product produced by casting concrete in a reusable mold or "form" which is then cured in a controlled environment, transported to the construction site and maneuvered into place; examples include precast beams, and wall panels for tilt up construction. In contrast, cast-in-place concrete is poured into site-specific forms and cured on site.

Domestic roof construction

Domestic roof construction is the framing and roof covering which is found on most detached houses in cold and temperate climates. Such roofs are built with mostly timber, take a number of different shapes, and are covered with a variety of materials.

Building insulation materials

Building insulation materials are the building materials which form the thermal envelope of a building or otherwise reduce heat transfer.

Sandwich panel Structure made of three layers

A sandwich panel is any structure made of three layers: a low-density core, and a thin skin-layer bonded to each side. Sandwich panels are used in applications where a combination of high structural rigidity and low weight is required.

Cold-formed steel Steel products shaped by cold-working processes

Cold-formed steel (CFS) is the common term for steel products shaped by cold-working processes carried out near room temperature, such as rolling, pressing, stamping, bending, etc. Stock bars and sheets of cold-rolled steel (CRS) are commonly used in all areas of manufacturing. The terms are opposed to hot-formed steel and hot-rolled steel.

Pre-engineered building

In structural engineering, a pre-engineered building (PEB) is designed by a PEB supplier or PEB manufacturer with a single design to be fabricated using various materials and methods to satisfy a wide range of structural and aesthetic design requirements. This is contrasted with a building built to a design that was created specifically for that building. Within some geographic industry sectors pre-engineered buildings are also called pre-engineered metal buildings (PEMB) or, as is becoming increasingly common due to the reduced amount of pre-engineering involved in custom computer-aided designs, simply engineered metal buildings (EMB).

In the Eurocode series of European standards (EN) related to construction, Eurocode 1: Actions on structures describes how to design load-bearing structures. It includes characteristic values for various types of loads and densities for all materials which are likely to be used in construction.

Cladding (construction) Layer of one material over another

Cladding is the application of one material over another to provide a skin or layer. In construction, cladding is used to provide a degree of thermal insulation and weather resistance, and to improve the appearance of buildings. Cladding can be made of any of a wide range of materials including wood, metal, brick, vinyl, and composite materials that can include aluminium, wood, blends of cement and recycled polystyrene, wheat/rice straw fibres. Rainscreen cladding is a form of weather cladding designed to protect against the elements, but also offers thermal insulation. The cladding does not itself need to be waterproof, merely a control element: it may serve only to direct water or wind safely away in order to control run-off and prevent its infiltration into the building structure. Cladding may also be a control element for noise, either entering or escaping. Cladding can become a fire risk by design or material.

Copper in architecture

Copper has earned a respected place in the related fields of architecture, building construction, and interior design. From cathedrals to castles and from homes to offices, copper is used for a variety of architectural elements, including roofs, flashings, gutters, downspouts, domes, spires, vaults, wall cladding, and building expansion joints.

The infill wall is the supported wall that closes the perimeter of a building constructed with a three-dimensional framework structure. Therefore, the structural frame ensures the bearing function, whereas the infill wall serves to separate inner and outer space, filling up the boxes of the outer frames. The infill wall has the unique static function to bear its own weight. The infill wall is an external vertical opaque type of closure. With respect to other categories of wall, the infill wall differs from the partition that serves to separate two interior spaces, yet also non-load bearing, and from the load bearing wall. The latter performs the same functions of the infill wall, hygro-thermically and acoustically, but performs static functions too.

References

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  2. European Convention for Constructional Steelwork. Committee TC7. Working Group TWG 7.3. (1983). European recommendations for steel construction : good practice in steel cladding and roofing. Constrado. OCLC   52910520.
  3. Steel Construction Institute (Great Britain) European Convention for Constructional Steelwork. Committee TC7. Technical Working Group 7.1. (1986). European recommendations for steel construction : the design of profiled sheeting. Steel Construction Institute. OCLC   154138387.
  4. European Committee for Standardization. British Standards Institution. Eurocode 1 : Actions on structures. British of Standards Institution. OCLC   456547815.
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  6. "Metals and Corrosion Resistance". The Engineering Toolbox. Retrieved 5 January 2016.
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  8. Kosaku Yoshino. "Stainless Steel Fasteners, Glaser & Associates, Inc". Glaser & Associates Inc. Retrieved 6 January 2016.
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  10. "Detail". The Visual Dictionary of Interior Architecture and Design: 73. 2009. doi:10.5040/9781350088719.0060. ISBN   9781350088719.
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