Unidome means up to:
35% weight reduction
20% lower energy consumption
20% less recessed reinforcement
10% less slab thickness
40% larger span
* compared to a solid slab
Benefits: reduced construction height, increased spans, increased construction durability, increased safety, increased comfort, accelerated construction process, reduced costs.
How to design a slab with Unidome shapers?
- Estimation of slab thickness and first run of FE- calculation:
Analogous to the design of a solid flat slab, a first slab rough slab thickness to start the FR – based computation is determined. Before running the calculation , a reduce dead load has to be taken into consideration on the impact-side (determineted by the weight of the solid slab reduced by the load reduction trough the concrete shapers /m2). At the same time, the bending stiffness of the cross section needs to be manipulated according to the Unidome tables. By applying both parametars to the entire slab, we assume 100% of the slab are covered with concrete shapers.
2.Verification of distribution of shear forces:
In order to guarantee the admired performance and in order to adapt the technology entirely, the distribution of shear forces has to be counterchecked. Unidome concrete shapers are admissible in all areas where the governing shear forces are less than 50% of the shear resistance of the solid flat slab.
VRD,UD=fshear*[ *fck) ] *b*d
fshear Factor for the consideration of the reduced shear resistance of a slab with cavities, to be taken from Data sheet
ꝩc Safety coefficient for reinforced concrete acc DIN EN 1992-1-1,184.108.40.206 NA 2.1
k Factor (scaling)
Ratio of longhitudinal reinforment related to the cross section ≤0,02
b Width of cross section
d Effective depth of the bending reinforcement in the considerd cross section
Concrete shapers have to be removed again in all areas providing higher shear forces, which happens to benear suppotings, providing that the initial assumption (concrete shapers covering the entire slab) is proven wrong. By those means partial solid areas are now established by re-manipulation dead load and stiffness back to solid properties.
Now that the slab design precisely provides separate for both areas (concrete shaper area and solid area) run a final calculation to check whether all results remained within the boundary condition.
Shear punching areas of columns/wall endings must not interfere with the Unidome areas. Also keep the minimum solid distance to the slab adges of 40 cm for XS and 60 cm XL if necessary.