The two spans are lenticular trusses with the top chord of each truss comprising a heavy tubular arch in compression, while the bottom chord comprises a pair of chains.
22.
A ceiling of tongue and groove boards is fixed between the bottom chord of the trusses with a section of double beaded boarding over the entrance to the middle bay.
23.
The deep profile corrugated fibrous cement main roof is supported on single span steel trusses which have a segmentally curved bottom chord and have been manufactured from riveted angle iron sections.
24.
Each half arch consists of two adjacent trusses laced together at top and bottom chord level and each truss consists of a top and bottom chord laced together in arch form.
25.
Each half arch consists of two adjacent trusses laced together at top and bottom chord level and each truss consists of a top and bottom chord laced together in arch form.
26.
For instance, in example one above ( C 79 ) the triad of E major is a ( compound ) minor 3rd away from C ( root of the bottom chord ).
27.
The chains are suspended 2 metres ( 6 ft 6 in ) beneath each bottom chord of the bridge and tensioned after building, by pulling the reinforcing posts into the vertical position.
28.
A ceiling has been installed in the hall area, attached to the bottom chord of the timber roof trusses but with diagonal timber supporting members protruding through it along the north-west and south-east sides.
29.
However, the varying'live'thrust forces of traffic downward on its deck are translated by the bowed chord above into horizontal tensions along the longitudinal iron eyebars of the'string'or bottom chord running parallel to the deck.
30.
This is resisted by pinning the lattice members to the top and bottom chords, which are more substantial than the lattice members, but which may also be fabricated from relatively small elements rather than large beams.
