Falls from elevation are a leading cause of fatalities and injuries among construction workers, especially in the residential construction industry. The majority of existing evidence regarding falls from elevation has described the demographics and occupational tasks of the victims, but little information is available on the causes or events that initiate fall incidents. A review of case reports suggests that lateral buckling of unbraced I-joists may be an important contributor to worker falls. Lateral buckling is an instability condition of beam failure where the beam twists out of plane. Beams or joists which undergo lateral buckling return to their undeformed state when the load is removed (fall has occurred). Falls caused by lateral buckling are most likely to occur when workers are installing temporary bracing or sheathing to unbraced joists and are walking from the end support towards the center of the joists. Lateral buckling can easily be prevented by providing clear direction to workers on what sections of a beam can be safely accessed for construction purposes, representing substantial savings in lost time and medical expenses. Little research has been published on the lateral buckling of wood I-joists, which are currently used in the majority of residential wood structures. The goal of this research is to explore the relationship between construction worker loadings and mechanical behavior causing lateral buckling of wood composite I-joists. First, observations of construction activities performed by workers on unbraced beams will be made. Next, a group of construction workers will perform these same activities in the laboratory environment where the loads caused by construction activities can be measured. A series of lateral buckling models will be created to describe the load where buckling occurs. Verification of these models will include experimental testing of lateral buckling using loads identical to those measured from construction activities. Based upon the loads measured due to worker activities and the modeling and subsequent experimental validation of lateral buckling loads for I-joists, safety strategies to prevent falls from elevation will be formulated. ? ? ? ? ? ? ? ?
