The precast components consist of hollow core slabs, beams, columns and staircase flights, a. Hollow core slabs
The design of hollow core slabs (215 mm thick) is based on class 2 prestressed concrete structure with minimum 2 hours fire rating. The hollow core slabs are cast with C50 concrete. Each unit (1.2 m nominal width) is designed as simply supported with nominal 100 mm seating at the support.
Resultant stresses are checked at serviceability and at prestress transfer. Design of the slab is carried out by the specialist supplier.
b. Precast beams
535 mm deep full precast beams are used in the office area. The beams, which are unpropped during construction, are seated directly onto column corbels and are designed as simply supported structures at the final stage. To limit cracking of the topping concrete at the supports, site placed reinforcement is provided as shown in the typical details in Figure 4.2.