The FDB Filigran punching shear reinforcement consists of spatial welded reinforcement elements with optimized geometry. The punching shear resistance of flat slabs is more than doubled by using FDB, featuring an increase by a factor of 2.1 of a reinforced concrete slab without punching shear reinforcement. According to the manufacturer, this increase factor is higher than that of other punching shear systems. This is the outcome of a comparison with stirrups in accordance with current design standards and double-head studs according to European Technical Assessment (Fig. 1).
The maximum punching shear resistance of slabs with stirrups used as punching shear reinforcement is exceeded significantly. While the use of double-head studs increases the resistance by 40 % compared to stirrups, the use of Filigran punching shear reinforcement improves the resistance by 50 %.
Design program of Filigran free of charge
The simple, parallel installation of the elongated elements of the Filigran punching shear reinforcement in the precast slabs with lattice girders, which are supplemented with in-situ concrete on the construction site, has proven its worth for many years. Additional tests were conducted and evaluated on the basis of a European evaluation document, and the conditions of application were newly assessed and extended.
Simplified verification of punching shear reinforcement quantity
The improved design concept with an adapted decay function for the tensions at wall edges and wall corners results in smaller areas which require punching shear reinforcement. The verification of the punching shear reinforcement quantity has been simplified. Maximum distances between the reinforcement elements were determined instead of an increase factor for the determination of the steel cross-section required for high loads. Due to these adaptations, the design result as a whole is more realistic and more efficient.