TATU City Warehouse Mezzanine Floor, Nairobi.
Somers Engineering was appointed as the post-tensioning specialist for the design and build of a Mezzanine Floor above the Warehouse spanning 15m between supports.
Post-tensioning technology was adopted as a value engineering option as there was a cost saving of 20% on the project. The post-tensioning design of the members resulted in a beam depth of 900mm with a clear span of 15m between supports.
Post-tensioning is a method of prestressing concrete that employs the use high strength steel tendons that are stressed after concrete placement. Post-tensioning allows for the creation of longer, slender spans with fewer supports hence allowing for thinner slabs thereby reducing material quantities and facilitating the design of aesthetically pleasing structures.
Post-tensioning offers direct cost reduction over conventionally reinforced members primarily by reducing concrete and rebar material quantities as well as rebar installation labor. Typically, savings between 10% -20% indirect cost are achieved
Factors contributing to direct cost reduction
• Thinner slab (1/3 of RC alternative) with less reinforcement
• Reduction of material quantities and cost
• Reduction of labor and material handling costs
• Reduced total building height and cladding cost
• Reduction of beams and steps- Simplified and cheaper formwork
• Rapid reuse of formwork- Less formwork needed on Jobsite