For a ladder beam to be TG20 compliant, moment resistance (restraint at 1.2m c/c) must be 12.5 kNm & shear resistance must be 8.3 kN.
780 Combisafe beams have resistances on a 4m span with a mid span load of 12.3 kNm & 6.2 kN (restrained at 1.0m c/c). There are no figures for 1.2m c/c restraint but at 1.5m, the figures drop to 7.6 kNm & 3.9 kN
Therefore 780 beams can't be used in place of steel ladder beams in TG20 compliant bridges.
The equivalent figures for 2 bay spans show that you need 3 x 780 beams to replace a single unit beam.
They cannot be serious! Or can they?
780 Combisafe beams have resistances on a 4m span with a mid span load of 12.3 kNm & 6.2 kN (restrained at 1.0m c/c). There are no figures for 1.2m c/c restraint but at 1.5m, the figures drop to 7.6 kNm & 3.9 kN
Therefore 780 beams can't be used in place of steel ladder beams in TG20 compliant bridges.
The equivalent figures for 2 bay spans show that you need 3 x 780 beams to replace a single unit beam.
They cannot be serious! Or can they?
