Future Steel Buildings/Properties
Properties of Structural Steel
Following properties of structural steel are considered before using them for a construction. These properties are useful for determining the quality of steel. High quality steel is used so that dependable and long lasting construction is possible. The most important components include the following:
- 1. Density
- Density of a material is defined as mass per unit volume. Structural steel has density of 7.75 to 8.1 g/cm3.
- 2. Elastic Modulus
- Elastic modulus or modulus of elasticity is the measurement of tendency of an object to be deformed when force or stress is applied to it. Typical values for structural steel range from 190-210 gigapascals.
- 3. Poisson's Ratio
- It is the ratio between contraction and elongation of the material. Lower the value, lesser the object will shrink in thickness when stretched. Acceptable values for structural steel are 0.27 to 0.3.
- 4. Tensile Strength
- Tensile strength of an object is the determination of limit up to which an object can be stretched without breaking. Fracture point is the point at which an object breaks after application of stress. Structural steel has high tensile strength so is preferred over other materials for construction.
- 5. Yield Strength
- Yield strength or yield point is the stress at which an object deforms permanently. It cannot return to its original shape when stress is removed. Structural steel made of carbon has yield strengths of 187 to 758 megapascals. Structural steel made of alloys has values from 366 to 1793 megapascals.
- 6. Melting Point
- There is no defined value for melting point due to the wide variations in types of structural steel. Melting point is the temperature at which object starts to melt when heated.
- 7. Specific Heat
- Specific heat or heat capacity is the amount of heat which needs to be applied to the object to raise its temperature by a given amount. A higher value of specific heat denotes greater insulation ability of the object. Values are measured in Joules per Kilogram Kelvin. Structural steel made of carbon has values from 450 to 2081 and that made from alloys has values ranging from 452 to 1499.
- 8. Hardness
- Hardness is the resistance of an object to shape change when force is applied. There are 3 types of hardness measurements. Scratch, indentation and rebound. Structural steel made by using alloys has hardness value between 149-627 Kg. Structural steels made of carbon has value of 86 to 388 Kg.
Components of Steel
Modern steel buildings are made of many individual components that have evolved over time. With the benefit of CAD manufacturers are able to produce more variations in dimensions and format of steel buildings. The building construction is done using different steel shapes and pieces. In most of the developed countries, standard approved shapes are available. Smaller steel buildings are prefabricated, so they are simple to assemble. The larger steel buildings require skilled workers so that safe assembly of the structure is ensured.
There are five main components of structural steel, including tension members, compression members, bending members, combined force members and their connections.
|Tension Members||Tension members can be found as web and chord in trusses and open web steel joints. They carry tensile and pulling forces preventing force to be applied on the other members used in construction.|
|Compression Members||Columns, Struts or posts make up the compression members. They are the vertical members in trusses and joists that are in compression.|
|Bending Members||Beams, joists, girders, spandrels, lintels are known as bending members. Each member has its own application but typically bending members carry moments and shear forces.|
|Combined Force Members||Combined force members are also known as beam-columns and are subjected to bending compression. Connecting members bring the entire building together.|
|Connections||Steel beam forms basic skeleton of the building and provides great support and strength. These beams usually hold the floor or the roof. I beams are widely used and come in different sizes. I beam can be used both as a beam and a column. The girder or I beam is used in construction of nearly all metal buildings. It gives strength in all directions. Every structural component of a steel building can be made by varying sizes of I beam. Similarly, Reinforced Bars is a type of steel rod which is used to create reinforced concrete. Steel rods are inserted into concrete to add strength and give flexibility to concrete. These bars are important in buildings made of concrete or which have substantial amounts of concrete used in construction. Steel joists are used to support floors or ceilings. These are laid in rows across girders. They are attached using joist hangers.|