BCGBC4010A Apply structural principles to residential low-rise constructions

Structural principles - Forces

Statics

Point load on a beam
Diagram 1
A picture of a beam with a column on either end supporting it is shown. The point load 6 kN is on the beam.
Diagram 2
A diagram shows how the 6 kN load is distributed evenly with 3 kN on each of the columns. The force moves down both columns.
Question
What reaction forces must be in operation to balance the resultant forces?
A.	An upwards force of 1.5 kN and a downwards force of 1.5 kN
B.	A downwards force of 3 kN on both columns
C.	An upwards force of 3 kN on both columns
D.	An upwards force of 6 kN
The correct answer is C - An upwards force of 3 kN on both columns. The reaction forces must operate up through the two columns and each force is 3 kN.
The reaction must be equal and opposite to the resultant downwards force of two 3 kN so the reaction must be an upward force of two 3 kN.

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