It's designed like any other pretensioned concrete, except the strands are horizontal. You have to locate a text that explains the design of pre-tensioned concrete. There are lots of them out there.
They have a stressing bed and six or so stands are tensioned. Size of strand and force depends on the design load of the strand. A maching connected to the bed 'extrudes' the hollow core shape, and the holes are the location of the augers that consolidate the zero slump concrete. I think the extrusion machine was invented by a guy named Spirol (sp?). The slab is hard enough that you can walk on it once the Once the concrete is placed the stressing bed is usually covered and the HC slabs are steam cured. Once cured, the HC slab is sawcut into the lengths required.
HC slab is often supported by bearing walls. A 'corolath' or masonite strip is placed on the wall and the HC slab is placed on it. This is to prevent any 'hard' points in the support. The walls have vert reinforcing extended above the floor and there are #4, 10M or 15M bars placed in the joints between the slabs. They are about 4' long with 2' extending on each side of the wall. Beams are similar, but may have 'hoops' extending at the ends of the HC slab. This is to engage bars or dowels that fit between the HC planks.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
