Experimental study of an innovative timber-concrete composite deck with a demountable dry-dry notched connection system

This paper presents an experimental investigation of an innovative Timber-Concrete Composite (TCC) deck with a dry-dry demountable connection system. The connections were made as notches, and the composite deck was assembled from a CNC-cut timber element and two prefabricated concrete panels joined at mid-span. The longitudinal joint between the concrete elements facilitated pre-activation of the deck, which has several advantages, including potential for pre-camber and a diminution of displacements induced by early-age shrinkage. All connections in the new deck were designed for disassembly to ease reuse of the materials at end-of-service-life and the environmental impact was reduced by adopting a carbon-minimized concrete mix design which resulted in semi-low strengths. The new deck system has been experimentally investigated through 14 four-point bending tests, comprising seven specimens designs with varying notch width, number of fasteners, and intended imperfections at selected notch mouths. The performance of the deck, in terms of connection efficiency and displacement capacity (ductility), was assessed and compared with 35 tests from the literature on existing wet-dry solutions. The findings revealed that the behavior of the new dry-dry deck system is comparable with existing wet-dry solutions. Most of the connections failed from concrete failures because of the low concrete strength, and when combined with a fastener, these failures exhibited a remarkable ductile local behavior, leading to elevated levels of global displacement capacity. The experimental study demonstrated a promising potential for improved structural behavior despite being more climate friendly.