Timber composite floor beams under 2 years long-term load

The long-term behaviour of composite beams is characterised by the response of its component parts (flanges and webs) to load, moisture content, temperature and relative humidity of the environment. This paper reports the results of a two years long-term test on two 6 m span composite floor beams made of laminated veneer lumber (LVL) under service load performed in an indoor, semi-controlled, and unheated environment. The environmental conditions were characterized by artificially induced cyclic air humidity with quasi-constant temperature. These conditions can be characterized as reasonably severe and presumably close to service class 3 according to Eurocode 5. During the test, the mid-span deflection, moisture content and air humidity were monitored. The paper recommends a creep factor for design of timber composite beams in severe environmental conditions