To calculate the bending moment of any point:
WL/2 x X - WX x X/2
W = Weight
L = Length of beam
X = distance
it occur where moment becomes zero in bending moment diagram.
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.
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
Shear force in a cantilever beam at the support due to a concentrated load is equal to the magnitude of the concentrated load (or sum of the loads) regardless of their position along the beam. Shear force in a cantilever beam increases linearly from zero at the free end to a magnitude of (wL) at the support, where w is the uniform load and L is the length of the beam.
Contrafluctre, or contraflecture, is the point in a bending beam in which no bending occurs. This is more readily and easily observed in an over hanging beam.
On SFD's and BMD's: The shear force will be 0, the shear force is the derivative of the bending moment at a point on shear force and bending moment diagrams. Otherwise: It depends on the loading.
0, bending moment is at maximum
moment
monment is force by distance however the deflection is a displacement of point measured by distance
To determine the internal shear forces and moments at any given point on a rigid body.
it occur where moment becomes zero in bending moment diagram.
the shear force diagram and the bending moment diagram are two separate diagrams each depicting their respective quantities.shear force and bending moment diagrams are extremely important as these two diagrams give what is needed of the beam that is to be designed. the procedure of sectioning the beam and finding the system of forces at the section is the most fundamental approach. for example the bending moment diagram can show at one glimpse the point of beam which is going to experience the maximum loading conditions and this point can be selected as the minimum requirement of the beam.
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.
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.
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.
Moment=>This is the turning effect of a force about a point
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.