Insight into mechanics of externally indeterminate hardwood–concrete composite beams

This paper presents tests on beech LVL–concrete slab composite connections and externally indeterminate beams using connectors comprising fully threaded (FT), small-headed screws or partially threaded (PT), large-headed screws in X-formation. A test was devised to quantify connection characteristics in fully cracked concrete (applicable to hog zones of the beams). Relative to the FT-based connections, the PT-based connections were of greater strength, nonlinearity and flexibility in compression concrete, and weaker, less stiff but more ductile in tension concrete. One composite beam exhibited 22% redistribution of support reaction at 88% of the failure load. Failure occurred primarily at the connections, which then gradually led to fracture of the LVL as a secondary mode of failure.