Steel is a common building material used throughout the construction industry.
Its primary purpose is to form a skeleton for the building or structure – essentially the part of the structure that holds everything up and together.
Steel has many advantages when compared to other structural building materials such as concrete, timber, plastics and the newer composite materials.
Steel is one of the friendliest environmental building materials – steel is 100% recyclable。
Steel, unlike wood, does not warp or twist and does not substantially expand and contract with the weather. Unlike concrete, steel does not need time to cure and is immediately at full strength. Steel is versatile, has more strength with less weight, has an attractive appearance, can be erected in most weather conditions, is of uniform quality, has proven durability and has low life cycle costs. These advantages make steel the building material of choice.
Steel as a building material has been studied and tested for many years. It might be said that we understand the behavior of steel better than any other building materials.
Structural design has evolved extensive with the advent of more research and new technology.
FROM DESIGN TO ERECTION
While the size and complexity of the project may drive and, in some way, change the process, the path of steel structural design and construction is predictable and proven.
Let us examine structural steel in the context of a building design requiring the services of an architect. However, there are many structures, constructed of steel, that do not require architectural input – these could include frames to mount equipment and machinery, offshore platforms, marine terminals, refineries, process plants and other non-aesthetic structures.
The production of conceptual, schematic and design development drawings are essential predecessor activities to finalizing the design of the structural framework.
In theory, it is the structural engineer’s job to make the vision of the architect come true. While most architects can appreciate the complexity of the structural design of their vision, only the structural engineer can gauge what needs to be done to satisfy the architect’s requirements.
After the architecture of the building is determined, the design of the framework – beams, columns, bracing etc. – proceeds with engineering calculations.
Structural engineering is the application of science and math to design a structure. With reference to the various building codes, the recommendations, and codes and the empirical data derived from all the testing done on steel structures, the structural engineer understands and can adequately predict the behavior of steel.
The engineer obtains other information from the architect on loads – dead load , live load , and special point loads . Initially, the structure must hold up its own weight ( dead load ) and must, in addition, hold up uniform and point loads (live loads ) that anticipate how the structure will be used during operation.
Detailing is the process of converting the structural design drawings to shop drawings. These shop drawings are used by the fabricator to identify the size, shape, and material grade of every single piece of structural steel in the framework.
Fabrication is the process of cutting, burning, welding , drilling, grinding, punching, bending, and generally producing the steel detail pieces shown on the detail drawings . The process of fabrication is systematic.
Erection is the process of erecting or connecting together the shipping pieces in the field at the project site. The success of erection is dependent on a few important factors. The first and most critical element is the erection of the columns. Column base plates are connected to the foundation using anchor bolts placed in the concrete by the foundation contractor. The location of the anchor bolts (usually four or more) for a single column in the foundation must match exactly the pattern of bolt holes in the base plate of a single column.
Problems in the design and construction of structural steel are, for the most part, caused by change. The change can result from an error, omission, or just the desire by one of the parties to change an element of the work, which then affects the structural design and geometry. As discussed earlier, the entire process involves four primary events – engineering, detailing , fabrication and erection. As a general rule the earlier in this four phase process the change is identified and modifications implemented, the less the impact on the project.