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For a long time, timber and concrete are dominant materials used in the construction. With the fast development of technology and technique as well as the rapid growth of ecnomy, steel construction is being extensively used in the modern design. And the properties of this material show that it is suitable for modernist architecture and it owns a lot of benefits during the constrution and for the later use.
Why is steel construction being widely used nowadays? Via the introduction of the background of modern architecture, the report is to make a detailed analysis of the three materials and their relavant constructions and tell the advantages and disadvantages of timber, concrete and steel from various perspect. Then, I'll give an example to discribe the use of steel construction in the world, which could tell the practicability and applicability of steel construction in the modern design. Finally make the conclusion.
Background of problem
Background of steel structure building
A steel building is a metal structure fabricated with steel for the internal support and, commonly but not exclusively, for exterior cladding. Such buildings are used for a variety of purposes including storage, office space and living space. They have evolved into specific types depending on how they are used.
They first gained popularity in the early 20th century.Their use became more widespread during World War II and significantly expanded after the war when steel became more available. Steel buildings have been widely accepted, in part due to cost efficiency. The range of application has expanded with improved materials,products and design capabilities with the availability of computer aided design software.
Background of Modern Architecture
Modern architecture is art with similar characteristics, primarily the simplification of form and creation of ornament from the structure and theme of the building. The first variants were conceived early in the 20th century. Modern architecture was adopted by many influential architects and architectural educators, however very few "Modern buildings" were built in the first half of the century. It gained popularity after the Second World War and became the dominant architectural style for institutional and corporate buildings for three decades. Modernist architecture has been more widely accepted as an appropriate residential style in Europe, where the populace is generally more exposed to culture and art than much of the world.
Characteristics of Modern Architecture
Modern architecture is usually characterized by:
an adoption of the principle that the materials and functional requirements determine the result
an adoption of the machine aesthetic
an emphasis of horizontal and vertical lines
a creation of ornament using the structure and theme of the building. Not rejection of ornamentation.
a simplification of form and elimination of "unnecessary detail"
an adoption of expressed structure
Form follows function
CHAPTER â…¡. LITERATURE STUDY
2.1 Main materials in buildings
2.1.1 Timber material
Strength depend on:
Grain direction. Wood is stronger parallel to grain than perpendicular to grain.
Load direction. Wood is stronger in compression than in tension.
Serve condition: Length of time the wood will be subjected to its maximum load,
temperature and moisture.
Size and shape of the piece.
Wood and steel are the only materials with tensile strength.
The availability of a wide range of timbers, means wood can be suitable for most
Wood is a highâ€performance material, low in weight, flexible, high in density, with
excellent loadâ€bearing and thermal properties.
With good design structural wood needs no chemical treatment to achieve a long life.
Wood is resistant to heat, frost, corrosion and pollution, but moisture needs to be controlled.
Wood's naturally good thermal insulation makes it the material of choice in cold
climates. But wood framed buildings are also efficient in hot climates, making use of
wood's natural ability to dissipate at night the heat built up during the day.
Wood provides a great sense of wellâ€being.
Almost every piece of timber contains one or more discontinuities that reduce its
structural strength and make it difficult to cut and shape.The most common ones are:
Knots: place where branches joined the trunk.
Knotholes: holes left by knots dropping out of wood and insect damage.
If wood was defectâ€free its strength would be similar as steel strength per unit length.
But due to the discontinuities is smaller.
Decay or insect damage may affect the wood's properties if they are still alive in the
The splits, crooks and twists produced in the seasoning process because of the shrinkage of the piece.
2.1.2 Concrete material
Concrete is a material produced by mixing fine aggregates, Portland cement and water.
The aggregates are usually gravel and fine sand.
Concrete reinforcement: As concrete has no useful tensile strength its application was limited in structural uses until the concept of steel reinforcing was developed. The compatibility between steel and concrete is fortuitous accident. The steel bars are putted where tension occurs and concrete is the responsible to resist compression.
Concrete is the universal material of construction.
Concrete does not burn.
Concrete is relatively low in cost.
It can be used for every building purpose.
Poured concrete structures rise relatively slowly and with the high cost of labour.
2.1.3 Steel material
Steel is one of a range of alloys of iron and carbon that contains less than 2% carbon.
Ordinary steel, called mild steel, contains less than threeâ€tenths of 1% carbon, plus a few
Carbon content is a crucial determinant of the properties of a ferrous metal. Too much
carbon makes a hard but a brittle metal, while too little produces a soft and weak material.
Thus, mild steel is iron whose properties have been optimized for structural purposes by
controlling the amounts of carbon and other elements in the metal. This alloy (ASTM A36) is the predominant type used in steel building frames, but nowadays, using scrap as their primary raw material, it is possible to produce a stronger steel (ASTM A572).
In time, this is expected to replace ASTM A36 as the steel used for most construction.
In locations where corrosion is expected to be a problem, steel structural members are often galvanized.
Strong and material.
Precise and predictable, what means accurate measurements.
Light in proportion to its strength.
Uniquely plentiful and inexpensive.
Long service life.
Risk of corrosion in certain environments.
Loss of strength during building fires.
2.2 Main construction types
2.2.1 Timber Frame construction
18.104.22.168 Heavy Timber Frame Construction:
Heavy timber is an economic alternative to steel and concrete, although quality of
forest has diminished and shipping cost have risen.
Large wood has a great capacity to absorb heat. For this reason, it is much slower to
catch and burn. It burns gradually and continues supporting its load while it burns. Instead,
unprotected steel would collapse. However large wood present some problems, it is subjected to large amounts of expansion and contraction due to the seasonal change in moisture content. Because of this, perimeter and floors must be supported on concrete or masonry. In spite of this, interior area can be supported on heavy wood columns.
22.214.171.124 Timber Light Frame Construction:
Properties is Light frame buildings are easily and swiftly constructed with a minimal investment in tools.and Wood Light Frame construction has its deficiencies:(1) If ignited, it burns rapidly.(2) If exposed to dampness, it decays.
2.2.2 Concrete construction
Concrete is reinforced to give it extra tensile strength; without reinforcement, many concrete buildings would not have been possible.
Reinforced concrete can encompass many types of structures and components, including slabs, walls, beams, columns, foundations, frames and more.
Reinforced concrete can be classified as precast or cast in-situ concrete.
Much of the focus on reinforcing concrete is placed on floor systems. Designing and implementing the most efficient floor system is key to creating optimal building structures. Small changes in the design of a floor system can have significant impact on material costs, construction schedule, ultimate strength, operating costs, occupancy levels and end use of a building.
2.2.3 Steel Frame construction
Building fires are not enough to melt steel, but are able to weaken it to cause structural failure. For this reason, building codes generally limit the use of exposed steel framing to buildings between one and three stories, where escape in case of fire is rapid and where collapse of the building is unlikely lo endanger people or other buildings. If the buildings
are taller, they must be protected from heat in order to buildings can be fully evacuated and the fire extinguished.
The main methods for fireproofing steel columns are(1) Encasement in reinforced concrete. (2)Enclosure in metal lath and plaster.(3) Enclosure in multiple layers of gypsum board. (4)Sprayâ€on fireproofing.
The main methods for fireproofing steel beams are(1)casement in reinforced concrete.(2)Enclosure in metal lath and plaster.(3)Rigid slab fireproofing.(4) spray- on fireproofing
Several recent highâ€rise buildings use very large steel pipe columns filled with very high
strength concrete to carry a major portion of both vertical and lateral loads.
126.96.36.199 Light Gauge Steel Frame Construction:
A Light Gauge Steel Frame is the nonâ€combustible equivalent of Wood Light Frame
construction. It may be insulated, wired and finished inside and out in the same way as a Wood Light Frame building.
Can be applied to singleâ€family homes and multiâ€housing.
Low weight (around 150Kg/m2).
It is possible to combine this technique with others.
Precision of measurements.
High degree of components prefabrication.
Rapid assembly because all the elements are manufactured to tight tolerances.
It is dry construction, what means reducing the risk of moisture problems.
Structure 100% recyclable because all the material have closed cycle life.
Combination of light gauge steel stud framing and gypsum boards provides a construction of high strengthâ€weightâ€ ratio.
Buildings with steel frame have a very long service life because steel's properties don't
change during its service life if it is well rust proofing. Hot dip galvanization prevents
steel from corrosion at least 100 years.
Light gauge steel framing from an environmental point of view:
Means less energy consumption during production than equivalent housing with a
framework of concrete poured onâ€site.
It uses one fourth of the amount of raw material used for equivalent homes of
Less waste means cleaner work site and low dead weight and this reduces the
Since steel's properties don't change during its service life, energy consumption
doesn't change either, keeping low all the time.
Steel constructions are easy to be disassembled and then reâ€use them because steel's loadâ€bearing capacity is maintained.
Structure 100% recyclable: All steel contains 10â€100% recycled steel and the high
quality of the material is maintained. New mineral wool is produced using 75% of the
original material and gypsum wallboards are made using 0â€10% recycled gypsum.
Steel is a very stable material and durable material, for this reason a smaller amount of
material is required than wood or concrete. Besides, since steel is also very exactly
dimensioned material, it can be supplied in exact lengths with no waste.
CHAPTER â…¢. CASE
3.1 case 1
In this chapter, I want to introduce one of most greatest modern Architecure in the world which made of steel construction in china. We are proud of this one.
Symbolic significance: the Chinese traditional culture methods hollowing, ceramics lines, the brilliant red and warm, and modern most advanced steel structure design perfectly blending together.design by Jacques Herzog and Chinese design group
The National Stadium is the main stadium of the 29th Olympiad in 2008. Occupying an area of 21 hectares, it has a floor space of 258,000 square meters. Its seating capacity amounts to 91,000, including 11,000 temporary seats.
The main body of the National Stadium is a colossal saddle-shaped elliptic steel structure weighing 42,000 tons. It is 333 meters long from north to south, 294 meters wide from east to west, and 69 meters tall.Building roof stadium saddle-shaped surface, long axis to 332.3 meters, 296.4 meters for the short axis, the highest height of 68.5 meters, the lowest height of 42.8 meters.
The main body's elements support each other and converge into a grid formation, just like a bird's nest with interlocking branches and twigs. Being a seven-story shear wall system, the stadium's stand has a concrete framework. The upper part of the stand and the stadium's steel structure are separated from each other, but both are based on a joint footing. The roof of the National Stadium is covered by a double-layer membrane structure, with a transparent ETFE membrane fixed on the upper part of the roofing structure and a translucent PTFE membrane fixed on its lower part. A PTFE acoustic ceiling is attached to the side walls of the inner ring.
The main body of the National Stadium has a design life of 100 years. Its fire resistance capability is first-rate, and it can withstand an eight-magnitude earthquake. The water-resistance capability of its underground project is also first-rate.
As we can see from the case upon, Chinese traditional culture and modern most advanced steel structure design perfectly blend together. In this chapter, I want to make an in-depth analysis from this specific one so that you will understand why steel construction is being widely used in the design of modern architecture.
The physical properties of steel, such as its durability, flexibility and strength offer significant advantages in the material efficiency of a product application. Steel is one of the most sustainable building materials with unique characteristics that favour its use in the construction industry.
(2)Steel for long lasting homes
The benefits of steel use and technologies in the homebuilding industry is gaining momentum and creating additional customer value. The strength to weight ratio of steel is the highest of any residential building material and it can be easily formed and joined. Because steel is strong and lightweight, it is beneficial for builders to work with and can be engineered to better withstand hurricanes and earthquakes. Steel is unique in that it is dimensionally stable. Unlike other materials that shrink, expand, warp and twist with age to cause settlement cracks or floor squeaks that require builders to make costly repairs.
(3)Steel for architecture
Steel offers new solutions and opportunities, allowing architects to expand their artistic expression and actually create some of the most challenging buildings they have designed in their minds. Today it provides not only strength to buildings, but also beauty and drama - enhancements that are difficult or too costly to produce with other materials. Curving and bending is now possible in ways that were never thought possible before. 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.
(4)Steel to build faster
The speed and accuracy of construction is critical to the creation of building and stakeholder value. 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.
(5) Steel for sustainable development
Steel has many significant advantages with regard to the demands of sustainable development. Compared with brick and concrete structure of residence, save energy and reduce air conditioning needs maintenance cost.
(6)Steel to optimize space
Reducing storey heights will cut the costs for steel and other building materials. From an energy-efficiency standpoint, minimizing floor-to-floor heights also helps curb heating and cooling costs.
(7)Steel for flexibility
Building owners often are faced with the challenge of modifying an existing space to meet changing needs. 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.
(8)Steel for earthquake safety
Light gauge steel framing is capable of meeting this standard due to its ductility and the strict process used to manufacture steel studs, the inherent properties of steel, and typical construction methods used in steel framing.
CHAPTER â…¤. CONCLUSION
Steel is one of the most sustainable building materials with unique characteristics that favour its use in the construction industry. The physical properties of steel, such as its durability, flexibility and strength offer significant advantages in the material efficiency of a product application.
Its benefits are for various aspects as follows:
Steel for sustainable development
Steel for long lasting homes
Steel for architecture
Steel to build faster
Steel for earthquake safety
Steel to optimize space
Steel for flexibility
Like every coin has two sides, steel cnstruction can't avoid being faced with some difficulties such as fireproofing, anti-corrosion and sound insulation. Now methods have been taken to solve these problems. Scientists and specialists are still developing and searching better measures.
To sum up, the design and performance of steel construction show significant meaning and value in the modern society and it will definitely become a trend in the modern architecture.
CHAPTER â…¥ . LITERATURE LIST
Allen, Edward (1999), Fundamentals of buildings construction : materials and methods.3rd edition. Ed John Wiley & Sons, New York.
Thelandersson, Sven ,Aasheim, Erik AASHEIM :New timber construction in Nordic Countries.Enginerred wood products Association. P069-
Johansson ,Marie , Kliger, Robert, : Steel and timber constructions , Chalmers University of technology
AISI - American Iron & Steel Institute
Living Steel ---- -----http://www.livingsteel.org/building-with-steel
BCSA (British Constructional Steelwork Association) - -------www.steelconstruction.org
Steel Framing Alliance ---------------www.steelframingalliance.com