Hybrid Buildings
Hybrid building structures are designed with multiple materials (steel framing with post-tensioned concrete decks or precast double tees; cast in place concrete frame with masonry in fill) to gain the greatest benefit of all materials within one structure.
Castcon Value Added
Compared to either cast in place or steel pan stairs, precast stairs erect 30% to 50% faster onsite. Call us for design assist in your stair tower. The Castcon staff is highly knowledgeable and helpful regarding code updates and code changes. If we don’t know the answer, we’ll find out for you immediately. Castcon precast stairs are cast indoors in our factory year-round and have a superior architectural grade finish at the time they are set in the building.
Stair & Landing
Hybrid buildings lend themselves to most any stair configuration. If the stair cores are cast in place concrete with steel framing, stairs with integral intermediate landings (Half-Z) with separate floor landings may be the best design. The integral landings can bear on shelf angles at the concrete wall and the floor landings can either sit on shelf angles or framing steel, depending on the design and location of the chase/air shaft in the tower. This design means only lifting three pieces into the tower instead of four, but it also allows for a joint between stairs and floor landings for additional erection tolerances.
Open Zee
This stair has integral landings at the head and foot. The head landing of one stair will be connected to the foot of an ascending stair, which means only two pieces per level must be erected. The landings must be supported at the ends. Open Zee stairs can be used in most structural tower designs (steel, masonry, cast in place, or precast). If the system is steel, then the mid-level landing will have to be suspended by a hanger rod from the floor steel and the floor level landing will rest on steel (support steel could be steel beams or tube steel). If the stair wall structure is masonry, then the stair landings will typically rest on shelf angles that are expansion-bolted to the concrete masonry units. If the stair wall is cast in place, they may be supported off of shelf angles, cast in ledges, or RVK’s. If the walls are precast, the stair landings may rest on precast haunches, ledger beams, shelf angles or other support designs.
Half – Z
This design is similar to an Open Zee except that it only has one integral landing (at either the head or the foot), hence the term “Half-Z”. This design would usually have an integral mid-level landing that is supported at the mid-level wall and rest on either a separate slab at the floor level or another type of bearing surface. If the mid-level landing is integral, then end-wall bearing support is needed. In a steel structure, this would be a hanger rod that is suspended from the floor steel (support steel can be steel beams or possibly tube steel). In a masonry structure, the landings would usually be supported off of a shelf angle. The floor landing would usually bear into the block. In a cast in place wall structure, they may be supported off of shelf angles, cast in ledges, or RVK’s. In a precast wall structure, the stair landings may rest on precast haunches, ledger beams, shelf angles or other support designs.