bending moment varies with the distance & the load carried by the beam. And also there is a hogging behavior and a sagging behavior occurs in the beam. According to the sign convention hogging and sagging bears opposite signs.(- & +). So if we are asked to find the maximum bending moment whether it is sagging or hogging we should consider the maximum value without considering the sign. That value is called maximum absolute bending moment.
0, bending moment is at maximum
When a cantilever beam is loaded with a Uniformly Distributed Load (UDL), the maximum bending moment occurs at the fixed support or the point of fixation. In other words, the point where the cantilever is attached to the wall or the ground experiences the highest bending moment. A cantilever beam is a structural element that is fixed at one end and free at the other end. When a UDL is applied to the free end of the cantilever, the load is distributed uniformly along the length of the beam. As a result, the bending moment gradually increases from zero at the free end to its maximum value at the fixed support. The bending moment at any section along the cantilever can be calculated using the following formula for a UDL: Bending Moment (M) = (UDL × distance from support) × (length of the cantilever - distance from support) At the fixed support, the distance from the support is zero, which means that the bending moment at that point is: Maximum Bending Moment (Mmax) = UDL × length of the cantilever Therefore, the maximum bending moment in a cantilever beam loaded with a UDL occurs at the fixed support. This information is essential for designing and analyzing cantilever structures to ensure they can withstand the applied loads without failure.
The term "point of contraflexure" is often used in structural engineering, specifically in the context of analyzing and designing beams subjected to bending loads. In simple terms, the point of contraflexure is the location along the length of a beam where the bending moment is zero. When a beam is subjected to bending loads, it experiences tensile (positive) bending moments and compressive (negative) bending moments along its length. The bending moment varies along the beam, reaching a maximum at the points where the bending is the most significant. These points are usually located near the supports of the beam. However, in some cases, particularly in continuous beams or beams with complex loading conditions, there may be a section along the beam where the bending moment changes direction from positive to negative or vice versa. This section is known as the point of contraflexure. At the point of contraflexure, the bending moment is zero, and the beam's curvature changes direction. This point is essential in the analysis and design of structures as it affects the internal forces and stresses within the beam. Identifying the point of contraflexure is crucial for engineers to ensure the beam's stability and design it appropriately to handle the bending loads effectively. The bending moment diagram is used to visualize the variation of bending moments along the length of the beam and to locate the point of contraflexure if it exists.
Bending moment is the same throughout the beam.
Positive and Negative are just directions. The main concern is whether there exist a bending moment or not. Then according to sign convention we classify bending moment as positive or negative. Elaborating on this point, If clockwise bending moments are taken as negative, then a negative bending moment within an element will cause "sagging", and a positive moment will cause "hogging" Sagging and hogging moments are important to differentiate. As hogging causes tension in the upper part of the beam x-section whereas sagging causes tension in the lower part of the x-section. This concept is of great importance in designing reinforced concrete members as we have to provide steel rebar in the zone of beam having tensile stress as concrete is weak in tension.
Shear is the rate at which bending moment changes or shear is its derivative with respect to span. The integral, bending moment, goes through a maximum when shear goes from positive to negative or vice-versa.
MAXIMUM SHEAR force bending moment is zero shear force change inside is called bending moment
0, bending moment is at maximum
When a cantilever beam is loaded with a Uniformly Distributed Load (UDL), the maximum bending moment occurs at the fixed support or the point of fixation. In other words, the point where the cantilever is attached to the wall or the ground experiences the highest bending moment. A cantilever beam is a structural element that is fixed at one end and free at the other end. When a UDL is applied to the free end of the cantilever, the load is distributed uniformly along the length of the beam. As a result, the bending moment gradually increases from zero at the free end to its maximum value at the fixed support. The bending moment at any section along the cantilever can be calculated using the following formula for a UDL: Bending Moment (M) = (UDL × distance from support) × (length of the cantilever - distance from support) At the fixed support, the distance from the support is zero, which means that the bending moment at that point is: Maximum Bending Moment (Mmax) = UDL × length of the cantilever Therefore, the maximum bending moment in a cantilever beam loaded with a UDL occurs at the fixed support. This information is essential for designing and analyzing cantilever structures to ensure they can withstand the applied loads without failure.
a simple definition " IT'S A COUPLE OF FORCE HAVING EQUAL MAGNITUDE BUT OPPOSITE IN DIRECTION & HAVING VERY LESS DISTANCE BETWEEN THEM"
It is the maximum stress at which a material will fail when subject to flexural ( moment producing) bending loads. These stresses occur a the material outer fibers.
Assuming linear elastic bending with small deformations and planes perpendicular to the neutral axis remain plane after bending, then for a rectangular beam: Moment = (Yield Stress)*(Second Moment of Area)/(Distance of surface to Neutral Axis) For Ultimate Bending Moment, assume stress is uniform throughout the beam, and acting through half the distance from surface to neutral axis, then: Moment = Stress * (Area/2)*(h/4 + h/4) For a better visualization check out Popov's textbook, Engineering Mechanics of Solids, Chapter 6, Section 6.10
It is the maximum stress at which a material will fail when subject to flexural ( moment producing) bending loads. These stresses occur a the material outer fibers.
Picture a beam cantilevered out from a wall with a weight hung off the outer end. The place it would need to resist bending the most is right next to the wall
moment
It depends on the loading conditions of the beam, it will generally occur close to the middle of the span.
Bending moment With "bending" you really mean the bending moment. The bending moment in an inner stress within a member (usually beam) that allows it to carry a load. The bending moment doesn't say anything about how much a beam would actually bend (deflect). Deflection Deflection measures the actual change in a material you could call "bending." It measures the physical displacement of a member under a load.