INVESTIGATION OF STRUCTURAL-PROPERTIES OF USED FORMWORK STRINGERS

Results of an experimental investigation of the structural properties of used slab formwork stringers are presented. The samples tested were obtained from eight concrete construction sites in Chicago, Milwaukee , and Minneapolis-St. Paul. All samples collected were 100 x 150 mm (4 X 6 in.) nominal-size solid lumber. Samples with legible mill stamp w ere Douglas fir. Grades varied from Select Structural to No. 2. Sample s were tested according to the guidelines specified by ASTM for lumber in structural sizes. This paper presents the observed values for shea r modulus, modulus of elasticity, modulus of rupture, and shear streng th parallel to grain. The observed structural properties are modeled w ith appropriate probability distributions. The observed data are used to investigate the correlation between stringer modulus of rupture and modulus of elasticity and modulus of rupture acid shear strength.