Static and vibration moduli of elasticity of salvaged and new joists

Conservation ethics and material shortages are stimulating interest in reusing wood products from demolished buildings and reusing entire buildings. As one of an anticipated series of reports coming from our research project titled, `Nondestructive structural evaluation of wood floor systems in historic buildings,' this paper reports the results of determining the modulus of elasticity (MOE) of wood joists via static and vibration methods in both edgewise and flatwise orientations. Fifteen new southern pine joists (2- by 16- in. by 30 ft.) and nine joists (2- by 16- in. by 20 ft.) salvaged from a 90-year old warehouse were examined. For the salvaged joists, a considerable difference was observed between the edgewise MOE and flatwise MOE for both vibration and static methods. Correlative relationships were found for both new and salvaged joists for vibration edgewise MOE versus stress wave MOE; static edgewise MOE versus stress wave MOE; static edgewise MOE versus vibration edgewise MOE; and for static edgewise MOE versus static flatwise MOE. These relationships may be useful in the ongoing research of structural evaluation of in-place floor systems.