In our composite system we make a distinction between basic construction variants.
1. V-HB-S, Timber+Concrete Composite, Standard Form
Single or multiple field systems. Here the composite structure is applied on the upper side of the timber beams. If the old shuttering is intact, i.e. if there is no damage to the wood of the timber beam, and if the defective floor cavity is filled with a sound insulating mass, then the old floor boards - provided they are properly anchored to the beam, can be treated as lost formwork. The minimum thickness of the concrete layer is 6 cm here.
Advantages of variant VHB-S:
+ Strengthening of the supporting structure by a factor of 10
+ No discernible residual vibration
+ Net increase of load bearing strength by a factor of 3
+ Statically rigid slab
+ Supporting structure provides transverse distribution
+ Single loads can be readily integrated
+ Levelling is possible
+ F90 fire protection of upper face
+ Improvement in solid-borne sound attenuation Δ Ln'w = 5-7 dB by the concrete
+ Interception of secondary sound travel by means of integrated wall connection
Points to be considered:
- Internal height of room decrease by at least 6 cm
V-HB-S timber concrete standard
2. V-HB-S, Timber+Concrete Composite, Thin Ceiling
Here the timber+concrete composite structure is implemented in the volume at the level, of the defective floor. Measured downwards from the top edge of the beam, a height of at least 6 cm is required. The SFix shear connectors are screwed into the beams from the side. The Elascon Floor C 25/30 F 6.5 G 8 LVB is now poured in field by field, so that it is finishes flush with the top edge of the beam. It is necessary to check that the defective floor making of the formwork can support the weight of the freshly poured concrete; this is 150 kg per square metre.
Advantages of the variant VHB-F
+ No loss of internal room height
+ Net increase of load bearing capacity by a factor of 3
Points to be considered:
- No supporting transverse distribution structure
- Fire protection must be implement on the upper face
- cost of implementation 15% higher
3. V-HBV, Variable Timber+Concrete Composite Ceiling
Essentially, this solution represents a combination of V-HB-S and V-HB-V. As a rule, the Elascon floor concrete is poured between and over the beams. Then the shear connectors are installed in accordance with the room geometry so that they work both in downward direction in the area of the defective floor and in upward direction into the pressure zone. To prevent the concrete breaking away again along the longitudinal axis of the beam, the beams require a concrete covering with a thickness of at least 4 cm. In addition, a reinforcement layer is used which limits fissuring.