Steel Design - Identification and Application PDF

Steel Design Steel design is a branch of structural engineering that deals with the design of steel structures. The main purpose of structural steel design is to check the viability of steel for any kind of project. Importance of steel in the construction industry The material provides strength th...

Steel Design Steel design is a branch of structural engineering that deals with the design of steel structures. The main purpose of structural steel design is to check the viability of steel for any kind of project. Importance of steel in the construction industry The material provides strength that is unavailable for buildings built with wood frames and brick walls. It does not warp, buckle, twist, or bend and is flexible and easy to install. Because of its increased quality and ease of maintenance steel is an attractive building material. Identification of Structures for which Steel is Practical for Use.  Parallel Flange Channels (PFC) These channeled beams are U- shaped with right angled corners, similar to the shape of a staple. They come in various different sizes, however, the two sides are always the same length and are parallel to one another. They also offer a high strength to weight ratio and have similar uses to angled sections.  Tapered Flange Beam It comes in an I-shaped and are also available in a vast variety of sizes. In construction, these are often used as cross-sections for girders. Though they have a particularly resistance ratio, it is not usually recommended when pressure is present along the length as they are not torsion (twisting) resistant.  Tapered Flange Beam  Universal Beam & Column (also called as American Standard Beam or Wide- Flange Shape) Universal beams and Columns, also known as I- beams or H-beams, come in the shape of their namesake: an ‘I’ when standing upright, and a ‘H’ on their side. They are usually made of structural steel and are used in construction industries and have a brilliant load-bearing capabilities..  Universal Beam & Column. Installation of Steel Columns (Wide Flange) using Boom Truck.mp4  Angled Sections Both will be right angled, however, unequal sections have different sized axis’ making them L-shaped.. Angled sections are used in residential.construction, infrastructure, mining and transport. Also, they are available in a wide range of lengths and sizes.  Angled Sections  Circular Hollow Sections Circular Hollow Sections come as a hollow tubular cross sections and have a much higher resistance to torsion than tapered flange beams. The density of the walls is uniform within the entire circle which makes this beam great for use with multi- axis loading processes.  Circular Hollow Sections LATTICE BEAM  Circular Hollow Sections  Circular Hollow Sections  Rectangular Hollow Sections These types of structural steel are much like the circular hollow sections, they are very popular in many mechanical and construction steel applications. Their flat surfaces make them prime for use in joining and metal fabrication.  Rectangular Hollow Sections  Rectangular Hollow Sections These are used within smaller applications such as columns or posts. However, they are unsuitable for beams as their shapes are inherently difficult to bolt into other types of shape. They are also known as ‘box sections’  Rectangular Hollow Sections  Flat Sections Arguably the most versatile type of steel section as they require to be attached to another section. In some cases, they can be attached to another section as a strengthening tool. They are also often referred to as ‘plates’ (for example, checker plates).  Flat Sections Ms Chequered plates fixing and welding of tie beam joint.mp4  T- Sections T section consists of flange and web arranged in “T” shape. They are used in steel roof trusses to form built up sections. Two angle sections can also be joined to get T section.  T- Sections  Deformed and Round Bars These bars contain circular cross sections and used as reinforcement in concrete and steel grill work respectively. It is available in various diameters. (10mm, 12mm, 16mm, 20mm, 25mm, 28mm, 32mm, 36mm, 40mm, 45mm, 50mm)  Deformed Bars Round Bars  Square Bars Square bars contain square cross sections and these are widely used for gates, windows grill works etc. the sides of square cross section ranges from 5 mm to 250 mm.  Square Bars  Rolling In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness, to make the thickness uniform, and/or to impart a desired mechanical property. The concept is similar to the rolling of dough. Producing Hot Rolled Steel.mp4  Two Types of Rolled Steel 1. Hot Rolled Steel Hot rolled steel refers to steel produced with extreme heat treatment. That is, the production occurs at extreme temperatures. Manufacturers begin with large, rectangular metals (billets). They then heat the billets before sending them for processing — a stage where they are flattened into large rolls.  Two Types of Rolled Steel 2. Cold Rolled Steel While making hot rolled steel only involves heating at high temperatures and cooling, cold rolled steel involves an additional process. At the cold reduction mills, the manufacturer cools the steel and re-rolls it at room temperature either by cold roll forming or press-braking. This process helps to achieve desired shape and dimensions.  Two Types of Rolled Steel Common Uses Hot Rolled Steel Automobile parts, e.g., wheel rims and frames Agricultural equipment Railway equipment, e.g., tracks and train components Construction materials Common Uses of Cold Rolled Steel Aerospace parts Rods, bars, strips, and sheets Mechanical components Metal furniture structures Home appliances Specifications and Building Codes. Specifications and Building Codes The design of structural steel is controlled and governed by building codes. These codes provide general guidelines of the minimum requirements for the design of a structural components or a system. These codes, which are actually laws or ordinances, specify minimum: Design Loads Construction Types Material Quality Other Factor Specifications and Building Codes Some of these codes are written specifically for certain areas and disciplines of an engineering practice. The design of Steel bridges is generally in accordance with specifications of the American Association of State Highway and Transportation Officials (AASHTO). Reinforce Concrete Structures are generally designed according to American Concrete Institute (ACI) Structural Steel Design is based on the specification of the American Institute of Steel Construction (AISC). Specifications and Building Codes The term building codes is sometimes used synonymously with specifications. More correctly, a building code is a set of rules that specify the standards for construction objects such as buildings and non-building structures. Specifications and Building Codes The main purpose of building codes is to protect public health, safety and general welfare as they relate to the construction and occupancy of buildings and structures. “The important thing to remember about specifications and building codes is that they are written, not for the purpose of restricting engineers, but for the purpose of protecting the public. No matter which building code or specification is or is not being used, the ultimate responsibility for the design of safe structure lies with the structural design engineer.” Philosophies of Design Philosophies of Design The design of structural members entails the selection of a cross section that will safely and economically resist the applied loads. Economy usually means minimum weight – that is, the minimum amount of steel. The fundamental requirement of structural design is that the required strength not exceed the available strength, that is, Required Strength ≤ Available Strength Methods of Design (ASD and LRFD) Methods of Design (ASD and LRFD) Allowable Stress Design (ASD) is a method of proportioning and designing structural members such that elastically computed stresses produced in the members by nominal loads do not exceed specified allowable stress. It is also known as Working Stress Design or Elastic Design. Required Strength ≤ Allowable Strength where, Allowable = Nominal Strength/ Safety of Factor Methods of Design (ASD and LRFD) Load and Resistance Factor Design (LRFD) is a method of proportioning and designing structural elements using loads and resistance factors such that no applicable limit state is reached when the structure is subjected to all appropriate load combination. This is mostly used in the design of steel structures. LRFD is similar to plastic design in that strength, or the failure condition, is considered. Factored Load ≤ Factored Strength ∑(Loads x Load Factors) ≤ (Resistance x Resistance Factor)