We are currently prefabricating 8 foot long brick jack arches for a project in Philadelphia that have no angle iron support under the brickwork. Oh the joys of design-build. Actually it has given us the chance to try a system that Ray Wethington invented, of using post tension #4 epoxy coated rebar through he length of the arch.
Post-tensioned is the descriptive term for a method of applying compression after pouring concrete and the curing process. 99% of the brick jack arches we prefabricate are set on steel angle irons, and it is the steel that carries the load of the weight above the masonry opening. We do make structural jack arches but code usually dictates steel reinforcement unless a historical variance is given.
For this job we are drilling a 1" hole into the brick before we prefab the arch. Then we are inserting the rebar that has a hook on one end and threaded on the other end. We then tighten a nut on the rebar threaded end giving the brick jack arch post tension strength. The dramatic effect is 8 foot straight spans with brick and joints visible from below.
