Jefferson Lab Site Tour

Experimental Hall C Post-Tensioning Cables - September 1991

Experimental Hall C - Construction Photo

September 17, 1991: Wrapping the "Post-Tensioning" cables around the Hall C "Tension Ring". These steel strands, which are stressed to over 70,000 PSI, resist the outward forces which will be produced by the weight of the earth that will ultimately cover the dome. The winding apparatus was pulled by a large tractor for hundreds of revolutions around the dome. Electronics mounted on the winder allowed the operator (standing on tractor) to precisely control the tension in the Post-Tensioning cables. The winder, and many of the techniques used in the construction of the domes, were invented and perfected by the subcontractor, Crom Corp.