Reinforced Wood I-Joists with Web Openings

Abstract

Prefabricated wood I-joists with web openings are commonly used in light-frame wood construction. The capacity and the failure pattern of such I-joists in the presence of a circular web opening were experimentally investigated on 100 specimens with various sizes and locations of web openings and two different span lengths of 3.66 m (12 ft) and 6.10 m (20 ft). The control I-joists, i.e., I-joists without any opening, failed in flexure in the midspan, whereas most of the I-joists with an opening failed in a brittle and sudden shear mode. The presence of an opening reduced the capacity up to 54% compared to I-joists without web openings depending on the size and location of the opening. Subsequently, to prevent brittle failure and improve capacity, the I-joists were reinforced using two perpendicular OSB collar layers with a variation in the reinforcement length. The effectiveness of reinforcing the web around openings was investigated on another 100 specimens. After reinforcement, brittle premature failure of I-joists was prevented with an increase in capacity up to 27% compared to the I-joists with openings. Analytical models to calculate the capacity of unreinforced and reinforced I-joists with openings are proposed, validated with results from previous research, which prove to be more accurate compared to existing models from the literature.