For ultimate strength and to fit within the client’s criteria, a truss design will be
used for the observation deck. Not only does a trussed cantilever better strength
than a suspension design it also ensures that there are no obstructions to the
view above the deck. This will give sightseers 360-degree views of the
breathtaking scenery around them.
Truss girders are an efficient and economical structural system where the
material is fully utilised. For short to medium spans, it is more economical to use
a parallel chord truss such as a Warren, Pratt or Howe truss as these designs
minimise the cost of fabrication and erection. However for short spans, a Warren
truss is more appropriate as it is more economical as it uses fewer materials than
a Howe or Pratt truss. For aesthetic purposes, it is ideal to have an even number
of bays on a Pratt or Warren design to avoid a central bay with cross diagonals.
A compressive member, or strut, is a component of a structure that
undergoes “pushing” forces when under load. This “pushing” or
“squeezing” force is constant throughout the member; both ends
experience the same force. When designing a compressive member on a
truss, some knowledge about how different members act when under a
load needs to be understood to get the ultimate strength out of the design.
When a load is placed onto a compressive member, it is stronger in one
plane compared to another and is just as likely to buckle in plane or out of
plane. To account for this, a compressive member should be designed to
be as short as possible with additional bracing considered to prevent any
A tension member is a component of a structure that undergoes “pulling”
forces when under load. Just like a compressive member, this force is
constant throughout the member with both ends experience the same
force. These members should be as compact as possible to allow for the
“stretching” forces that they undergo. A tension member should be kept
as light as possible while still be structurally strong to keep overall costs
down for the structure.
Patented by James Warren in 1848, theWarren truss is the most popular and
recognisable truss bridge design in the world. This design uses equilateral
triangles to spread loads, minimising forces to only compression and tension. As
a load moves across a Warren truss bridge, centre members can swap between
compression and tension depending on the position of the load. With minimal components, this design requires fewer materials than others, making it the
most economical for short spans.
When it comes to light, strong materials for constructing the scaled model, there
is no better economically viable material like Balsa Wood. Being quite a dense
timber, Balsa is the only timber in the world that is both a hard wood and a soft
wood due to its properties. With a range of dens