Introduction
Although steel was first produced in the Middle Ages, its use in structural engineering did not begin until just over a century ago. Today, numerous emblematic steel structures demonstrate the possibilities offered by this material.
There are several reasons to choose steel as a primary construction material, including its excellent strength/volume ratio, its wide range of applications, the availability of standardized parts, its reliability, and its ability to shape almost any architectural idea.
Index
Introduction
History of Steel.
Variety of steels
The steel designs
The Eurocodes
Characteristics and Advantages of Steel for Construction
Types of steel and their different uses in construction
steel classification
How to choose the right type of steel for your project
There are several reasons to choose steel as a primary construction material, including its excellent strength/volume ratio, its wide range of applications, the availability of standardized parts, its reliability, and its ability to shape almost any architectural idea. Quality and manufacturing control guarantee the safety and resistance of the structures. Carefully designing the details, prefabricating in modern workshops equipped with trained personnel and advanced corrosion protection systems, guarantees an almost unlimited service life with minimal maintenance.
Steel is a revolutionary material in the construction industry for its ability to offer endless design possibilities. Steel structures are characterized by their outstanding physical and mechanical properties, with high resistance to bending and compression.
History of Steel.
Steel is an alloy of iron and carbon, which can also include other components depending on its end use. Its importance as a material is reflected in iconic constructions that have marked the history of the industry, symbolizing the beginning of a new era at the beginning of the 20th century: the Modern Era.
Although metal structures have their roots in the 18th century, steel structures as such became popular in the second half of the 19th century. At this time, steel production techniques were improved, a more resistant and industrialized material than puddled iron. This boosted the steel industry, and with the Industrial Revolution, steel became the most used material in construction, surpassing even iron.
Although steel was first produced in the Middle Ages, its use in structural engineering did not begin until just over a century ago. Today, numerous emblematic steel structures demonstrate the possibilities offered by this material.
There are several reasons to choose steel as a primary construction material, including its excellent strength/volume ratio, its wide range of applications, the availability of standardized parts, its reliability, and its ability to shape almost any architectural idea. Quality and manufacturing control guarantee the safety and resistance of the structures. Carefully designing the details, prefabricating in modern workshops equipped with trained personnel and advanced corrosion protection systems, guarantees an almost unlimited service life with minimal maintenance.
Steel is a revolutionary material in the construction industry for its ability to offer endless design possibilities. Steel structures are characterized by their outstanding physical and mechanical properties, with high resistance to bending and compression.
Steel is an alloy of iron and carbon, which can also include other components depending on its end use. Its importance as a material is reflected in iconic constructions that have marked the history of the industry, symbolizing the beginning of a new era at the beginning of the 20th century: the Modern Era.
Although metal structures have their roots in the 18th century, steel structures as such became popular in the second half of the 19th century. At this time, steel production techniques were improved, and a more resistant and industrialized material than puddled iron. This boosted the steel industry, and with the Industrial Revolution, steel became the most used material in construction, surpassing even iron.
Three steel constructions that marked the history of this material are:
• Joseph Paxton's Crystal Palace, built in London in 1851.
• The Gallery of Machines in Paris, built in 1889 and designed by the engineer Ferdinand Dutert.
• The Eiffel Tower in Paris, was completed in 1889. The latter is a 300-meter-tall steel construction that he further popularized as the new construction material at the time. For this reason, from the year 1900, it was increasingly common to see it in all kinds of buildings.
In the first half of the 20th century, steel buildings were very successful in countries like the United States. Skyscrapers like the Chrysler or the Empire State Building in New York were built largely out of steel. It is interesting to note that 60,000 tons of steel were used to build the Empire State. The Brooklyn Bridge is another iconic steel structure, where four steel cables support the bridge deck while attached to anchor towers. After World War II, steel became a material present in most construction projects. With its different shapes and alloys, it presents physical and mechanical properties such as elasticity, corrosion resistance and ductility that make it perfect for construction. In addition, the inherent advantages of steel have been significantly enhanced thanks to the constant effort of the steel structure industry to improve its performance in an increasingly competitive world.
Variety of steels
Steel production has evolved significantly since its first processes that produced material of uncertain composition and variable properties. Today, most of the steel used in structures is produced through the basic oxygenation process and modern refining processes, which result in a fine-grained material with excellent weldability, strength and toughness properties.
In recent decades, steel production methods have experienced impressive progress. Since the mid-1970s, steel productivity has increased considerably, from producing between 60-100 kg/man-hour to 1,250 kg/man-hour in modern steel mills. This has had a significant effect on material costs.
In addition, investments in new and better rolling mills have gone hand in hand with improvements in basic production. Today, the hot rolling mill can produce profiles with a greater variety of shapes, tighter tolerances, better finish and more homogeneous composition. Temperature-controlled lamination allows full control and improves the mechanical properties of the product. Also, the cold rolling process can be used to produce a coil of strapping that is later turned into a wide variety of profiles.
This revolution in manufacturing techniques has been the cause and effect of a major restructuring of the entire steel industry. Notably, the European Coal and Steel Community, one of the components of the European Community, was established in 1952 to ensure the restructuring of these crucial industries after World War II. Although it has been a difficult, long and painful process for the industry, it has led to the emergence of a new, modern and healthy steel industry.
The steel industry has innovated and although low-carbon steels remain a popular choice due to their good quality and low cost, there is now a wide range of commercially available structural steels. High-yield strength steel has become increasingly popular as it allows designers to create structures at a more competitive cost. In addition, it is now possible to specify steels with thermodynamically controlled rolling to obtain improved mechanical properties. An example of the improvement in the mechanical properties of steel is the Eiffel Tower, which required almost 7,000 tons of steel when it was built in 1888, but if it were built today, only 2,000 tons would be needed.
The range of available steels also includes materials with resistance to corrosion, which is especially useful in the construction of bridges and other structures exposed to the environment. Stainless steels are a popular choice and are available in a variety of compositions and finishes, allowing designers to create durable and attractive structures.
Additionally, cold-rolled steel is widely used in cladding, allowing for the creation of a wide variety of colours and finishes. Coated steel products are also widely used in siding, providing increased durability.
The steel designs
Steel design was considered a complex art in which proficiency was acquired after 20 years of arduous experience. Although experience is still important, designers now have more resources and precise tools to support their work. Computers have simplified levels of analysis that previously required large amounts of manual calculation. Codes of practice are more understandable and limit state design concentrating the designer on the most relevant aspects of a project. Evolution in frame design A modern example is the box girder bridge.
Steel box girders are used as main members in the superstructure of bridges with spans between 50 and 150 meters in length. In addition, this type of system presents good torsional rigidity characteristics, which makes it a viable alternative in the design of curved bridges.
Steel box girders in particular have characteristics that make them a favourable type of support system in certain scenarios. They are mainly composed of a lower fin joined by two souls (commonly inclined) to two upper fins. In addition, they are normally found in two types of configurations: concrete deck composite beams and orthotropic deck beams.
This elegant structure allows the use of wide wings, reducing the height of the structure. The inherent torsional stiffness of the closed section is used to distribute eccentric loading effects over the full width of the section, thus reducing peak bending stresses. Internal diaphragms are used to hold caisson parts together during manufacturing and reduce the torsional resistance of the closed section.
Steel fabrication and production have become more efficient with the introduction of new technologies and processes. Productivity in the steel industry has doubled in the last decade of the 20th century, thanks to the implementation of numerical control machines that have reduced preparation and material handling time, thus contributing to improving product quality. Today, profile shot blasting is a technique commonly used in steelmaking to improve the surface quality and durability of the material. Steel Design Previously, steel design was considered a complex art in which proficiency was acquired after 20 years of painstaking experience. Although experience is still important, designers now have more resources and precise tools to support their work. Computers have simplified levels of analysis that previously required large amounts of manual calculation. Codes of practice are more understandable and limit state design concentrating the designer on the most relevant aspects of a project. Evolution in frame design A modern example is the box girder bridge. This elegant structure allows the use of wide wings, reducing the height of the structure. The inherent torsional stiffness of the closed section is used to distribute eccentric loading effects over the full width of the section, thus reducing peak bending stresses. Internal diaphragms are used to hold caisson parts together during manufacturing and reduce the torsional resistance of the closed section. Manufacturing Steel production has become more efficient with the introduction of new technologies and processes. Productivity in the steel industry has doubled in the last decade of the 20th century, thanks to the implementation of numerical control machines that have reduced preparation and material handling time, thus contributing to improving product quality. Today, profile shot blasting is a technique commonly used in steelmaking to improve the surface quality and durability of the material.
The Eurocodes
The Eurocodes represent the fruit of many years of hard work, compiling the best available information on the design of steel and composite structures. Two examples highlight the refinements achieved in structural form, thanks to a better understanding of structural behaviour, analysis and design. The first is the portico, the object of much research from 1950 to the present day. This elegant minimalist structure has an inherently efficient shape, as its centre line closely follows the thrust guideline, thus minimizing deflecting moments and achieving uniform distribution of resistance. With a modern plastic or elastic design, the frame allows the redistribution of moments, adjusting the bending diagram as much as possible to the uniform resistance diagram associated with prismatic sections. Also, to resist the peak moment in the cantilever, reinforcement can be used. Elastic analysis and modern manufacturing methods allow the construction of a frame whose variable resistance distribution conforms to the elastic bending moment diagram.
Characteristics and Advantages of Steel for Construction
Steel is a material widely used in construction due to its own characteristics. It is ideal for rapid construction, easy to transport and assemble, and its cost is low compared to other materials such as reinforced concrete. In addition, it has several advantages as a structural and construction material, such as:
Resistance: steel has great mechanical resistance, which makes it suitable for the construction of tall buildings and bridges.
Durability: With proper maintenance, steel constructions can withstand physical and chemical conditions throughout their useful life.
Ductility: steel has the ability to withstand deformation once its elastic limit is exceeded, maintaining its mechanical capacity. It is a material that admits deformations without failure.
Versatility: steel adapts to any type of application thanks to its physical and mechanical properties.
Uniformity: the properties of steel remain unchanged over time.
Toughness: steel has a high fracture toughness.
Elasticity: the steel reaches many stresses and approaches a linearly elastic behaviour.
Recyclable: steel is a 100% recyclable and degradable material. In the construction industry, around 85% of the steel used worldwide is recycled.
Structural steel is one of the best materials to carry out construction quickly and is long-lasting and sustainable. Its use has been key in the development of large cities since buildings, bridges or tunnels can be built with it.
Types of steel and their different uses in construction
Steel is a material widely used in the construction of structures for Civil Engineering projects due to the inherent mechanical properties that make it an ideal candidate for the construction of high-rise buildings, cable-stayed and suspension bridges, electric power transmission towers, offshore platforms and more. However, before deciding to use steel in your project, it is important to understand the different types of steel and their specific characteristics.
Steel is classified into four categories based on its chemical composition:
Carbon Steel: Most steel products fall into this category, and it is divided into three subcategories: low, medium, and high carbon. For structural shapes, low-carbon steel is used due to its high malleability and ability to be manufactured in a wide variety of shapes and sizes.
Alloyed Steel: Other elements such as manganese, phosphorus, sulphur, copper, nickel, chromium, molybdenum, vanadium, cobalt, or niobium are added to steel to give it additional properties such as increased strength, weldability, or ductility.
Stainless steel: It is an alloy that contains between 10% and 20% chromium, and may also contain nickel and molybdenum. This gives it excellent resistance to corrosion and wear.
Tool Steel: Some steel alloys are made with the intention of increasing their hardness, durability, and strength. These can contain tungsten, molybdenum, cobalt and vanadium in different amounts. They are mainly used for the manufacture of heavy-duty tools.
Steel is a material widely used in the construction of structures for Civil Engineering projects due to the inherent mechanical properties that make it an ideal candidate for the construction of high-rise buildings, cable-stayed and suspension bridges, electric power transmission towers, offshore platforms and more. However, before deciding to use steel in your project, it is important to understand the different types of steel and their specific characteristics.
How to choose the right type of steel for your project
To choose the right type of steel for a construction project, it is essential to consider various characteristics and mechanical properties. Among the elements to take into account are: the resistance, rigidity, ductility, weldability and tenacity of the steel, as well as its location in the structure. In addition, there are different types of steel, each with unique characteristics, which fit different needs.
For example, Corten steel is a corrosion-resistant material with a reddish colour, which is mainly used in metal structures, facades and doors. Rebar is a steel sheet made up of bars with reliefs, which is easily adhered to and used in conjunction with concrete. Galvanized steel is a type of zinc-coated steel that is highly resistant to corrosion and is used in items that are in contact with water.
On the other hand, rolled steel is used in the structure of buildings and Civil Engineering works, and there are different profiles, such as the plate, LI/LM or LD angles, CE channels and IR profile, each with its own applications. It is important to know the mechanical properties of each type of steel, its chemical composition and the products that are manufactured on the market to determine which is the most suitable for each project.
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