falsework

plural falseworks

1. uncountableusuallyengineeringA temporary framework used in the building of bridges and arched structures in order to hold items in place until the structure is able to support itself.

   Each [girder] measuring 38 metres long, they will sit below four steel tripods which will support the falsework and formwork.

   2024 May 17, “Network News: Viaduct carrying HS2 into Curzon Street takes shape”, in RAIL, number 1009, page 11

   1 more example

   Both steel and timber forms were used, supported on a falsework of steel beams erected on the new abutments at each end and on temporary piles which were driven into the river bed at mid-span.

   1955 February, “Notes and News: Construction of River Leen Bridge”, in Railway Magazine, page 140

2. uncountableusuallyengineeringScaffolding, a temporary frame serving to support and brace a building under construction until it can stand alone.

   ... the woefully incomplete Ferris Wheel ... was a half-moon of steel encased in a skyscraper of wooden falsework.

   2003, Erik Larson, The Devil in the White City, page 236