PLAIN AND CIVIL: 4.0 SHEAR AND MOMENT IN BEAMS

Sunday 24 March 2019

Beams are structural members which receive lateral loads. Beams are sometimes called with different names such as purlins, shafts, elements, etc.

4.1. TYPES OF BEAMS

CANTILEVER BEAM. A type which has one end fixed and the other end free. With fixed support, all the reactions forces and moment are usually present in the fixed end.
SIMPLY SUPPORTED BEAM. A structural member which has supports located at its two ends.
OVERHANGING BEAM. A part of the beam which hangs out from the supports. This type of beam usually appears as an overhang of a simply supported beam.
FIXED BEAM. A fixed beam has both its end fixed rigidly. With two ends having 3 reactions each, this type of beam is usually indeterminate.
CONTINUOUS BEAM. A beam types which includes more than two simple supports which create 2 or more segments of the beam.

4.2. TYPES OF LOADS

POINT or CONCENTRATED LOAD. Load applied at a very small segment of the beam, like a point.
DISTRIBUTED LOAD. Load which is constant all throughout a segment of the beam. This kind of load is usually applied per unit length.

UNIFORM DISTRIBUTED LOAD. Illustrated as a rectangular distributed load. Load is constant from start to end of the application.
TRIANGULAR DISTRIBUTED LOAD. Load which starts from zero to a certain value.
TRAPEZOIDAL DISTRIBUTED LOAD. Combination of uniform and triangular loads.

3. COUPLE LOAD. Type of beam load by moments or by opposite, but equal magnitude loads.

Click for pdf notes on SHEAR AND MOMENT IN BEAMS

4.3. FINDING REACTIONS ON BEAM SUPPORTS

Reactions on the supports of beams would be determined by using the usual equilibrium of equations. Similar with the procedure on how you determined the support reactions on a truss, start with the summation of forces if applicable before moving on to summation of moments.