final-report-of-the-advisory-committee-on-falsework-bragg-report - Flipbook - Page 112
Movement of falsework
Early in 1972 the steel falsework for the construction of the span of the southern
carriageway over the River Loddon had been erected without incident and used
to support the full weight of the concrete deck. In August 1972 operations were
commenced to move the falsework to the corresponding span of the northern
carnageway.
Skates were fitted under the trestle legs and single rows of sheet piles were
placed horizontally on top of, and welded to, each 33 in x 11 ½ in steel foundation
beam, forming a flat track along which the assembly was hauled to its new
position by means of a pulling device, operated from each bank of the river.
Checks were made after every foot of travel and no difficulties were experienced.
The falsework for the southern carriageway of the river span had been thoroughly
inspected by an experienced person before concreting of that span took place.
This inspection had revealed many bracing members missing and some bolts
not properly tightened; these defects were rectified before the concrete was
poured. A thorough check was made and certain defects were rectified before
the concrete was poured on the falsework for the northern carriageway.
Concreting operations
On the day of the collapse the pouring of the concrete had commenced at
8.30 a.m. and the intention was to complete the continuous pour of 750 cubic
yards by 6 p.m. on the same day. Of this, 500 cubic yards would be carried by the
falsework between the piers. The remaining 250 cubic yards, was to extend
the deck over the permanent piers just beyond the trestles to the adjacent
spans, where it would be supported by other falsework.
Four reciprocating type pumps were used. The concrete was conveyed from the
pumps, through flexible pipes to the placing positions. Four separate gangs
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Part Section Through Finished Bridge
113
