what is static equilibrium?
rest or COM is at constant velocity
what is principle of transmissibility?
forces can be moved along their lines of action without changing their overall effect on any rigid body
what do we draw on a FBD?
all forces and moments ON a body
what are the types of supports?
simple
pin joints
encastre
what are the types of simple supports?
knife edge
frictionless pin
what do simple supports do?
transmit forces in 1 direction
what do pin joints do?
transmit vertical and horizontal forces
what do encastre supports do?
transmit vertical forces, horizontal forces and bending moments
what type of forces occur in beams?
shear forces and bending moments
how do we work out internal forces and BM?
calculate external forces
make a cut along beam and draw FBD of one section
resolve forces
take moments about cut
what are sagging moments and what happens here?
moments that are negative
centre of beam is lower than edges
what are hogging moments and what happens here?
moments that are positive
centre of beam is higher than edges
what type of distortion takes place with tension?
elongation
what type of distortion do moments cause?
change in curvature
what can we assume about distortion with slender beams?
distortion due to tension and shear forces are negligible to BM
what does it mean if a beam is rigid?
no distortion takes place
what is shear force and BM like for point loads?
S = constant
BM = linear with respect to distance
what can sometimes happen to S with point loads?
there is a discontinuity at the point load
what does UDL stand for and what does it mean?
uniformly distributed load
load spread evenly along beam
where does weight act on a UDL?
total weight acts through COM
what is the relationship between S and length of a UDL?
linear
what is the relationship between BM and length of a UDL?
parabolic
what is shear force like at a pin joint?
constant throughout, unless an extra load is applied at the pin joint
what happens in a Macauley bracket when inside is negative?
set to 0
