After a night in Salzburg and experiencing the local Wiener Schnitzel (very nice) at the Old Fox we headed out early to experience a day learning more about the capabilities of glulam. Our guide for the day was Johannes Rebhahn of WIEHAG, thank you for your time and patience during the day, sometimes I know it was like herding cats.
Our first stop was at a new Porsche-VW distribution centre for the region. This is a very typical project demonstrating the use of glulam beams. The building has a concrete base and precast concrete beams produced locally covering a total area of 9000m2. The main beams are some 15m in length with spans of 7.5m between columns. The secondary beams are actually longer at 22m. The roof, which was being rapidly swung into place, is OSB panels with roof joists. The glulam being used was normal strength glulam of an industrial quality i.e., not of a high visual grade. The range of joints used is visible in the photos, neoprene once again being used at the point of contact between timber and concrete. Most of the structure was prefabricated offsite including positioning of connectors. The whole timberwork will take 5 men only 6 weeks, to build.
Of note is that this is regarded as a typical and very regular construction, there is nothing complicated about this and the very rapid build time is clearly a great benefit.
The WIEHAG factory is headquartered in Altheim, Upper Austria, and has over 160 years of experience in timber construction. Founded in 1849 as a small carpentry shop, WIEHAG is now one of the leading providers of bearing systems, roofs and glulam products. With around 300 employees, WIEHAG generates annual sales of roughly €77 million, with an export rate of around 75%. The production volume is currently 85,000m3 pa. The focus is glulam especially curved and complex projects.
The factory was a fascinating experience and having spent many years in manufacturing industries I always enjoy seeing the assembly of products. The tour started with a lunch and slide show of the capabilities of WIEHAG including the new rail station in Canary Wharf London and a 50m beam used in the Bangor leisure centre. Imagine the transporting of that 50m beam, I am sure no sharp turns were involved. A quick look at the references page on their website will show you some of the projects. The longest beams have been the 50m length and 2.5m deep. All products are PEFC certified and now FSC is being added as an option. Larch is also available as an option and provides a redder colour to the product
The business has been making glulam products since the 1950s. Projects include an exhibition hall at Karlsruhe involving 600m3 of timber; Audi is a big customer, and the Wels exhibition hall, which is discussed later, has a 90m free span. Other projects include University of reading Library, Tesco (UK) warehouses, garden centres, Spar group centre, top tower Bavaria and a speed skating hall in Eilat Israel with a 105m diameter. All products for projects are designed in house and as much work is done as possible in the factory including fixing plates.
The factory takes spruce boards, racks them and then kiln dries them. These are then processed into the factory where they are quality graded, planed and then finger jointed into the required length for the glulam sections. Every piece is quality checked for colour and cracks. Quality checking includes an x-ray examination for faults. The lengths of board are then glued together and compressed in a series of clamps until the glue dries. The clamps also provide the ability to bend and shape the sections to the required curvature. Once the large boards of glulam are glued and dried they are passed through a CNC machine to provide any additional cuts for the project. The beams then have any additional fixings added prior to packing and shipment. It is worth noting that the factory structure is glulam exhibiting its capabilities.
From what I could see the manufacturing process was not overly complex but was incredibly efficient well planned and used cutting edge technology (CNC) to refine the product as required. This was a very efficient factory delivering a high quality and very flexible product. Just have a look at their website to see what a versatile product glulam can be.
Wels exhibition Centre
After our visit to the factory we headed out again to the Wels exhibition centre currently housing a large camping and caravan show. This is a large/ very large hall covering some 16,000m2 and using 5,500m3 of timber. This was a project, which involved a high degree of prefabrication and consequently a short construction time.
Our first visit in the hall was to observe the roof above the large glulam arches of the main halls. These open halls have spans of 90 meters, achieved by using two massive curved glued laminated timber arches as a top chord and a post tensioned timber bottom chord with struts from steel tension cables.
The 90m span was made out of two smaller spans of 46m, the near maximum size which could be prefabricated. The large size required a specialised transport system for the 46m lengths, 5.85m width and weight of some 43 tonnes. Moved at night the route required a 40m turn and necessitated the removal of traffic lights and rail barriers. Four cranes were required to lift these beams into place and the construction was completed in 5 months.
The exhibition hall is massive and a real tribute to the capabilities of glulam. The whole building is further insulated, with triple glazing and blinds to manage the light input. This is a classic example of how glulam constructions can be used for large arenas and warehouses, with the prefabrication permitting a fast construction time.
- Architecture: AT4 Architekten ZT GmbH
- Structural analysis: DI Georg Hochreiner
- Construction: STRABAG, DYWIDAG, and WIEHAG