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If clockwise bending moments are taken as negative, then a negative bending moment within an element will cause "hogging", and a positive moment will cause "sagging". It is therefore clear that a point of zero bending moment within a beam is a point of contraflexure—that is, the point of transition from hogging to sagging or vice versa.
Likewise the normal convention for a positive bending moment is to warp the element in a "u" shape manner (Clockwise on the left, and counterclockwise on the right). Another way to remember this is if the moment is bending the beam into a "smile" then the moment is positive, with compression at the top of the beam and tension on the bottom. [1]
In the absence of a qualifier, the term bending is ambiguous because bending can occur locally in all objects. Therefore, to make the usage of the term more precise, engineers refer to a specific object such as; the bending of rods, [2] the bending of beams, [1] the bending of plates, [3] the bending of shells [2] and so on.
An influence line for a given function, such as a reaction, axial force, shear force, or bending moment, is a graph that shows the variation of that function at any given point on a structure due to the application of a unit load at any point on the structure. An influence line for a function differs from a shear, axial, or bending moment diagram.
The sign of the bending moment is taken as positive when the torque vector associated with the bending moment on the right hand side of the section is in the positive direction, that is, a positive value of produces compressive stress at the bottom surface.
In mathematics, the moments of a function are certain quantitative measures related to the shape of the function's graph.If the function represents mass density, then the zeroth moment is the total mass, the first moment (normalized by total mass) is the center of mass, and the second moment is the moment of inertia.
Although the moment () and displacement generally result from external loads and may vary along the length of the beam or rod, the flexural rigidity (defined as ) is a property of the beam itself and is generally constant for prismatic members. However, in cases of non-prismatic members, such as the case of the tapered beams or columns or ...
The bending moment applied to the beam also has to be specified. The rotation φ {\displaystyle \varphi } and the transverse shear force Q x {\displaystyle Q_{x}} are not specified. Clamped beams : The displacement w {\displaystyle w} and the rotation φ {\displaystyle \varphi } are specified to be zero at the clamped end.