Large-span glued wooden structures (LGWS) are large dimension building structures manufactured by joining, both along and face-to-face, of wood lamels using modern, reliable, and environmentally safe glue systems. These are frames, beams, arches, frameworks, poles, columns, etc.
In recent decades, in Europe, North America, Japan, when making decision on erection of large-span buildings and structures expected to have unique architecture and design, it often occurs that LGWS versions are preferred. In their performance characteristics, LGWS are no worth than concrete or metal structures. High strength characteristics and aesthetic features stimulate wide use of large-span glued structures in construction of buildings and structures of various purposes. First of all, if there is any necessity to overlap large spans with no intermediate supports while structure components are expected to become interior and exterior decorative elements. These may be any gymnasiums, swimming pools, restaurants, pavilions, concert and exhibition halls, decorative sheds, bridge structures, office buildings, and many other objects.
Since LGWS are expected to be used for overlapping large spans, any such project requires development of an architectural design and work papers. All structure elements are manufactured in a production process based on working drawings. Planed, calibrated, and shaped workpieces are used for cutting components, making various tenonings, notches, milling, drills, trimming for metal fasteners, etc., then unit assembly is performed. Thus, stable product quality and precision of all its components are ensured. Disassembled components are easy to be delivered to a building site.
Comparing LGWS bearing capacity with that of reinforced concrete and metal structures shows that in case of equal bearing capacity, wooden structures are weighing much less. This means less expenses for your foundations, too.
Wooden bridgings may be compared, with regard to their fire resistance, with reinforced concrete and metal ones:
1. we know that metals have high thermal conductivity. Thus, a metal quickly becomes hot in fire, its plasticity increases, while its bearing capacity lowers. Being rather heavy, such structures quickly collapse. Fire protection coatings for metals are expensive but not durable.
2. in reinforced concrete, metal works in tension with concrete being pressed. With temperature raise, irregularly heated concrete becomes cracking and losing its baring capacity. Concrete and metal lose their interaction, reinforcement structure becomes caved in, and the entire structure crushes immediately under its own weight.
3. generally, LGWS components have rather large cross sections. In any design, safety factors shall be taken into account. You probably noticed that large firewood pieces never start to burn immediately but gradually are charred from the outside (wood has low thermal conductance, so its internal parts are heated slowly). Some data published show that wood is charred with average rate of 0.65 mm per minute, so in an hour, cross section of a wooden part decreases from 30 to 40 mm. Even with no fireproof coating, the structure will not crush immediately, and the time required for the provided safety factor of the structure to exhaust may be calculated. And since wooden glued structures are easier and cheaper in processing them with fireproof materials, their advantage over reinforced concrete and metal ones is evident.
A great advantage of LGWS is their resistance to aggressive environments. With low operating expenses, wooden structures in aggressive environments – for example, in animal farm buildings, mineral fertilizer warehouses or those for acids, bases, and other chemicals may serve longer than those made of reinforced concrete or, especially, metal.
If you are planning to arrange a roof over your swimming pool, you ought to understand that having used LGWS processed with protective agents you will never more think much about wet air impacting it along with chlorine and other substances used for water disinfection and bearing structure corrosion caused by them. Instead, you will enjoy yourself looking at architectural forms of visible wooden beams, nice patterns of wood texture, appreciating its true nature creating friendly atmosphere disposing to rest.