Structural engineering

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(Redirected from Structural engineer)

Structural engineering is the field of civil engineering particularly concerned with the design of load-bearing structures. In practice, it is largely the implementation of mechanics to the design of structures, such as buildings, bridges, walls (including retaining walls), dams, tunnels, etc.

Structural engineers need to design structures so that while serving their useful function, they do not reach collapse (structural failure or ultimate limit), and do not bend, twist, sag or vibrate in undesirable ways (serviceability limit). This is usually done using limit state design. In addition strucutral engineers are responsible for making efficient use of funds and materials to achieve these structural goals. Typically, apprentice structural engineers may design simple beams, columns, and floors of a new building, including calculating the loads on each member and the load capacity of various building materials (steel, timber, masonry, concrete). An experienced engineer would tend to design more complex structures, such as multi-story buildings (including skyscrapers), or bridges.

Loads are generally classified as: live loads such as the weight of occupants and furniture in a building, the forces of wind or weights of water, and the forces due to an earthquake; or dead loads including the weight of the structure itself and all major architectural components.

Traditionally, structural engineering used careful placement of coordinate axes to simplify complex equations associated with tensor quantities such as stress and resulting deflection of structural elements, such as beams. This simplification was essential to being able to solve problems. A successful engineer must design a structure to withstand the loads specified to be placed upon it. As long as the design loads are not exceeded the structure should spring back when the load is lifted, or hold steady indefinitely. The advance of computer software has allowed many of the more complicated calculations to be carried out more accurately and quickly.

One of the most important structural analysis methods is static analysis. The sum of the forces acting on the structure are equal to the sum of the supporting reactions - the forces acting on the structure are in equilibrium.

Static analysis can be performed manually or by using computer and other methods including finite element analysis software. Due to the complexity and time constraints imposed in modern projects, computer analysis will commonly be used as a primary tool for structural analysis. Manual checks will only be performed on global structural behaviour and critical elements.

The materials that make up the structure are often assumed to be homogeneous and to deform elastically.

Another analytical method is called dynamic analysis. It involves calculating the dynamic properties, such as vibration periods and vibration shapes of the structure, to determine the maximum internal forces of all structural members when they response to external shaking. Dynamic analysis is very common in seismic design due to the dynamic nature of earthquake. Since only the maximum forces of each structural members can be calculated, the analytical result will no longer be in equilibrium. A simple method called Equivalent Static Method has been created to overcome this issue by simulating a set of static forces. However this method gives meaningful result only when the structure is regular and mass is uniformly distributed, which rarely occur in real project.


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