Structural steel designing is the science of creating the basic framework of any structure, such as buildings, bridges, skyscrapers etc. This framework has to be strong enough to withstand all kinds of external forces like earthquakes and storms. The structural design is the skeleton of a structure, it should be strong enough to sustain the roof load, imposition of other building materials, and floor loads.
Structural steel fabricators use certain methods for designing structures. Below is a list of some commonly used methods:
Simple Design
This is the most commonly used type of design. In this design, it is assumed that no moment is transferred from one connected member to the other members or the structure as a whole. This method assumes the design structure to be pin jointed. Simple design method involves following a few assumptions:
All connections of beams, girders, and trusses are virtually flexible and proportioned for reaction shears applied at the appropriate eccentricity.
The plane sections normal to the axis remain plane after bending.
Continuous Design
In this design, it is assumed that members are rigid and the moment is transferred between members. Continuous design is way more complex than simple design, so various software are used to analyze the frame. In this design, frames are capable of resisting lateral loads without relying on the additional bracing system for stability.
The two main advantages of this method are:
Connections perform better in load reversal situations or earthquakes.
Beams can be less deep in comparison to beams in the simple design method.
Semi-Continuous Design
This design method is more complex than simple and continuous design methods. Analytical routines to study the behavior of close connections requires sophisticated computer software. It is to solve this problem that there are two simplified procedures for braced frames and unbraced frames.
-The wind moment method for unbraced frames.
-The semi-continuous design method for braced frames.
Plastic Design
This method of design is relatively newer compared to the other designs. This design is difficult to implement. One major drawback of the plastic design is that structural usefulness of the material is limited up to the ultimate load. Therefore it is important to determine the ultimate load capacity and strength of the joint. The stiffness of the joints is important when it comes to calculating beam deflection, sway deflections and sway stability. The plastic design method is more economical compared to simple and continuous designs.
Structural steel fabricators have to be adept with these methods to work on huge construction projects. It is for this purpose that structural fabricating companies hire certified metal fabricators. Northern Weldarc has a team of specialized structural steel fabricators who can take care of all your fabrication needs.
