TAREA- VIDEOS FUNDAMENTOS
FORCES
NORMAL FORCES
SHEAR FORCES
that are oriented in the vertical direction, parallel to the beam cross-section
that are oriented along the axis of the beam, perpendicular to the beam cross-section
usefulness of shear force and bending moment diagrams
Shear force and bending moment diagrams are used to analyse and design beams. By showing how the shear force and bending moment vary along the length of a beam, they allow the loading on the beam to be quantified.
Beam Loads and Supports
The most common ways of applying loads to a beam are concentrated forces, distributed forces, and concentrated moments. Distributed forces can be uniform, or non-uniform.
DISTRIBUTED FORCE
CONCENTRATED FORCE
CONCENTRATED FORCE
SUPPORTS
FIXED SUPPORT
ROLLER SUPPORT
PINNED SUPPORT
(NO) vertical displacement (NO) horizontal displacement
(SI) rotation
.
(NO) vertical displacement (SI) horizontal displacement ( SI) rotation
(NO) vertical displacement (NO) horizontal displacement
(NO) rotation
SIGN CONVENTIONS
A consistent sign convention needs to be used when calculating shear forces and bending moments. The most common sign convention is as follows
If the beam is on the left side of the imaginary cutting plane shear forces pointing downwards are positive. If the beam is on the right side of the cutting plane, shear forces pointing upwards are positive.
If a bending moment causes sagging then it is positive, and if it causes hogging then it is negative.
Applied forces are positive if they are acting in the downwards direction.
Stresses in Beams
But the state of stress within the beam includes shear stresses due to the shear force in addition to the major normal stresses due to bending although the former are generally of smaller order when compared to the latter.