Composite Wood-Concrete Beams Using Utility Poles: Time-Dependent Behavior

Abstract

This paper describes the behavior of wood-concrete composite beams in which the wood layer is composed of recycled utility poles. Two full-scale laboratory specimens of 7,500-mm (295-in.) span were constructed, with the concrete slab cast on the timber poles left unshored. The connection was obtained by cutting six notches in the timber poles. A threaded steel dowel is placed in each notch extending through both layers with a nut on the bottom of the beam that can be tightened once the concrete has cured. Since the material in each layer exhibits a time-dependent response, it is necessary to examine the effects of sustained loading. After 28 days of initial curing of the concrete layer during which the midspan deflection was monitored, both beams were subjected to the service load to estimate the composite efficiency. The beams were very stiff and values of 96% and 98% were obtained, respectively, demonstrating the high efficiency of the notched connection system used. A comparison was made with results o...