Precast system for industrial buildings
Industrial roof systems are the pride of Italian prefabrication in the world. ONDAL® is the last and most advanced precast system for industrial use patented under the surname Dal Lago. The previous are the Dalla, Ura no, Tit ano, Nike, Pitti and Star systems.
The system has been patented and launched on the market in 1988 and since then it has been subject to a constant evolution up to the patent of 2012 (ONDAL 12 ®), characterised by several functional innovations . The product has been getting a foothold at international level due to its performance. It is estimated that more than 16 million square metres of precast buildings have been made with the ONDAL® system from 1989 mainly in Italy, France and Spain, but also in Latin America and Northern Africa.
The ONDAL® system allow s the construction of large structures completely precast with wing -shaped pre- stressed slab members distanced by shells, pre -stressed beams, columns and foundation footings in reinforced concrete. It is cladded with precast concrete panels. Dry mechanical connections are used, allowing for a high speed assemblage.
The structural optimisation of the system brought to the attainment of an average m3 of concrete over m 2 of the building ratio as low as 0,12. Lightness, architectural appeal and economy are among the fa ctors that allowed its success.
The ONDAL 12® system is based on three technologic al solutions based on the maximum bay a chievable :
01. ONDAL standard: 12 x 30 m
02. BigONDAL: 12 x 42 m
03. ONDAL Strallo: 75 x 30 m
ONDAL SLAB MEMBER
The ONDAL slab member is a wing-shaped member with average thickness of 7 c m and subsequent high lightness. It is produced in the depth of 70, 100, 120 and 150 c m and they are mounted at an inter -axis of 6 m interposing between slab and slab shell elements.
His reduced weight allows to cover long spans:
For longer spans, a closed core lightened element named BigONDAL is been engineered.
Th e maximum spans a chievable are:
Despite the low thickness , the position of the pre- stressing tendons provides a high fire resistance of all roof members .
The clear spa cing of 3,5 m left between ONDAL elements mounted at an inter -axis of 6 m is covered by s hells of the following types:
used singularly or in c ombination. Metallic sheet, ventilation chamber and thermal insulation are placed on top of the grid concrete shells, making a ventilated roof.Shed elements are compatible with the installation of photovoltaic panels.
All ONDAL 12® elements are energetically optimised to have high thermal performance both for heating with the elimination of thermal bridges and for cooling with natural ventilation .
The shells are provided with air valves that ensure the remotely controlled air change of the environment and that automatic ally enter in function in c ase of fire, expelling smoke.
Beam, column and foundation elements
The pre-stressed beams that support the ONDAL roof elements generally have I cross-sectional shape. Cranes are installed on TT pre-stressed beams.
The beams are installed and connected on top of rectangular or square cross -se ction c olumns with c orbels. The rain water is taken down to wa ste through ducts that c an be inside the cross section of the columns or c an run externally.
The Strallo has been engineered to cover bays of up to 30 x 75 m. The ONDAL Strallo system c an be employed to build exceptional span structures such as hangars of exposition pavilions. The beam element has an omega shaped cross- section and hosts inside it an a cce ssible catwalk where also equipment can be distributed. The ONDAL standard elements are supported on this beam.
The beam is supported at the edges on top of pylon corbels and along its span by steel c ables that are anchored in the pylon top bulbs. The high pylons are only placed in the inner bays, whilst the perimeter of the building is made with standard modular frames.
The cladding panels , placed vertically or horizontally, a re made with reinforced concrete with continuous thermal insulation pla ced in between the inner grid screed and the outer suspended screed.
In between the two concrete layers a natural ventilation chamber c an be left . The panels and their connections are energetically optimised so to get a total envelope transmittance U down to 0,2 W/m 2K.
Several finishes techniques c an be mechanically applied to the outer surface of the panels, also in combination, among which: