Sagging and hogging bending moments are 2 types of moments a structure can experience. A structure can bend upward or downward.
Table of Contents
What Is Sagging Bending Moment?
Sagging bending moment is a type of bending moment that causes the concave side of a beam or structural member to experience tension or elongation. When a beam is subjected to external loads, such as a downward force or weight, it induces internal forces and moments within the beam. These internal forces are known as bending moments.
In the case of sagging bending moment, the external loads cause the beam to bend in a concave shape, resulting in the bottom fibers of the beam being stretched or put under tension. The magnitude of the sagging bending moment is highest at the location where the beam experiences the greatest deflection.
To ensure the structural integrity of a beam, we must consider the sagging bending moment along with other factors such as the material properties, dimensions of the beam, and the applied loads. Engineers analyze and design beams to ensure that they can withstand the anticipated bending moments without failure or excessive deformation.
What Is Hogging Bending Moment?
Hogging bending moment is a type of moment in which beam is bent in a manner that the top part of the beam is stretched or pulled, while the bottom part is compressed or pushed. It creates a bending force that causes the beam to curve upwards in the middle.
Hogging ding moment can occur when a load is applied to the top of the beam, causing the top part to stretch and the bottom fibers to compress. It is called “hogging” because the beam appears to be hunched or hog-like in shape.
Hogging bending moments can be important to consider in structural engineering and design, as they can affect the strength and stability of the beam. Engineers need to make sure that the beam is able to handle the bending forces and not exceed its limits, so they can design safe and reliable structures.
Read also: Shear Force and Bending Moment Diagram for Simply Supported Beam
Sagging Vs Hogging Moment: Differences
Here are simplified table for sagging and hogging bending moments.
| Sagging Bending Moment | Hogging Bending Moment | |
|---|---|---|
| Definition | Beam bends like a smile. | Beam bends like a frown. |
| Beam Behavior | Normal condition for the beam. | Beam is under too much pressure. |
| Shape of Beam | Beam goes up in the middle. | Beam goes down in the middle. |
| Stress Distribution | Bottom of the beam is stretched, top is squeezed. | Bottom of the beam is squeezed, top is stretched. |
| Reinforcement Design | We make the bottom stronger. | We make the top stronger. |
| Critical Sections | The important part is at the bottom. | The important part is at the top. |
| Failure Possibility | Can break if stretched too much at the bottom. | Can break if squeezed too much at the bottom. |
| Common Causes | Putting too much weight or pushing too hard. | Taking away support or uneven pushing. |
| Structural Integrity | Not too bad for the beam. | Very bad for the beam, could break it. |