In structural engineering, understanding the types of loads and supports is essential for designing stable and efficient structures. This article explains the different types of loads that beams experience and the various types of supports used in construction.
Types of Loads
A beam is typically horizontal, and the loads acting on it are generally vertical. Below are the main types of loads:
1. Concentrated or Point Loads
A concentrated load is a load that acts at a specific point on the beam. Although, in practice, it is distributed over a small area, it is idealized as acting at a single point.
Example: A person standing at the center of a wooden plank supported at both ends.
2. Uniformly Distributed Loads (U.D.L)
A uniformly distributed load is spread along the length of a beam such that the rate of loading (ω) is constant. This means each unit length of the beam carries the same load.
- Expression: Loading rate (ω) is in N/m.
- Example: A bookshelf loaded uniformly with books.
3. Uniformly Varying Loads
A uniformly varying load has a loading rate that changes along the beam’s length. Typically, the load starts at zero at one end and increases uniformly to the other end, forming a triangular distribution.
- Example: A sloped roof covered with snow.
4. Dead Loads
These are the loads due to the self-weight of structural members, such as beams and columns.
- Example: The weight of a concrete slab.
5. Live Loads
Live loads are temporary or movable loads, such as people, furniture, and equipment within a structure. These loads are also referred to as superimposed loads.
- Example: Occupants in a building.
Types of Supports
To ensure stability, beams are supported in various ways. Here are the common types of supports:
1. Simple or Free Support
A simple support allows the beam to rest freely on it. It exerts a reaction force perpendicular to the support surface.
- Example: A plank resting on two bricks.
2. Hinged or Pinned Support
A hinged support permits the beam to rotate but not translate. The reaction force passes through the hinge or pin and can act in any direction.
- Example: A drawbridge mechanism.
3. Built-in or Fixed Support
A fixed support restricts all movement and rotation of the beam. This type of support ensures complete restraint in both position and direction.
- Example: A cantilever beam attached to a wall.
Summary
Understanding these load types and supports is crucial for designing safe and efficient structural systems. By analyzing the distribution and type of loads, engineers can select appropriate support mechanisms to ensure stability and durability.
The reaction will pass through the centre of the hinge or pin and can be in
any direction.
There will be no restraint to the angular rotation of the beam at the hinge.
iii) A built-in or fixed or encastred support.
It is that support which restrains complete movement of the beam
both in position as well as direction.