Above ground multi-storey car parks

Parking garage
United States

Many multi-storey parking garages in the United States use a 2-way-post tensioned concrete slab with a composite honeycomb (castellated) high strength steel girder system of 450-480 N/mm2 (ASTM A852- Grades 65 and 70). The slab pre-stressing prevents cracking and moisture penetration. The steel frame, approximately 30kg/m2, is about 20% lighter than a traditional steel structure and much lighter than concrete, thereby reducing foundation costs.

Interaction of the concrete slab and HSS offers the following advantages:
  • Deflection of the composite sections is less than that of the beam alone
  • The concrete slab prevents lateral torsional buckling of longspan beams
  • The efficiency of the composite section means that the beam carries mainly tensile forces
  • Spans up to 20 meters are achieved easily which, in combination with the honeycomb beams (castellations), provide a very open structure that requires less artificial lighting.