Engineering sections are the shapes that are most commonly used in the design of civil engineering structures like I-section, T-section, L-section etc… These sections are used in building columns, roof trusses, cantilevers, bridge girders, beams, stadiums, etc…
some common engineering sections are as shown below;
Engineering sections are of two types. These sections are either;
- Symmetrical sections
- Unsymmetrical sections
Sections will be called symmetrical, if a given section is cut around axes such that one portion is the exact image of the other. The axis with respect to which section divided is known as axis of symmetry.
Sections are symmetrical with respect to following three types;
- Symmetrical Sections with respect to x-axis
- Symmetrical sections with respect to y-axis
- Symmetrical sections with respect to both x-axis & Y-axis
Symmetrical Sections with Respect to X-axis
If a section is split with respect to x-axis such that section on one side of x-axis is exact image of the section that lie on the opposite face of x-axis, then section is said to be a symmetrical section with respect to x-axis. As shown below
Symmetrical Section With Respect to Y-axis
If a section is split with respect to y-axis, such that section on one side of y-axis is the exact image of the remaining portion of the section that lie on the opposite face of y-axis. Then this section is said to be a symmetrical section with respect to y-axis.
Symmetrical Section with respect to X-axis & Y-axis
if a given section is cut from either half x-axis or y-axis and such that one portion of a section is exact image of the other than it is said to be a symmetrical section w.r.t. x-axis and y-axis. As shown below.
A section will be unsymmetrical section, if a given section is cut around axis such that one portion of a cut section is not the exact image of the part of section that lie on the opposite face of axis. As shown in figure below.
The above sections are the example of unsymmetrical sections. If these sections are cut around their axis, then portion of section on both sides of axis will not be the same.