InTrans / Aug 14, 2018
Curved Glulam Beams In Changing Relative Humidity
The is project deals with curved timber beams and researched to determine how changing relative humidity conditions affect the deflections and bearing capacity of small bending specimens, loaded for the longer period of time (one year). Beams were made from European spruce and glued with resorcinol-phenol-formaldehyde type of glue. The 15 of 20 beams of special shape, assuring radial tension failure, were loaded with load equal to 1/3 of ultimate load for the period of one year, while continuous measurings of strains and deflections were carried out. After recording residual deformations at unloading, failure tests to determine residual bending strength of previously loaded beams were performed.
Some results were similar to those of straight beams (creep is more pronounced in high moisture conditions, bending strength is affected by moisture content more as by long-term load), but also some interested effects can be observed by tension perpendicular-to-grain.