Indicative comparisons between bonded and dowelled hardwood studs for limecrete–spruce connections under load–unload–reload double-shear testing

This paper reports double-shear testing of hardwood stud-based connections between limecrete slabs and spruce glulam beams. Limecrete–glulam composites can form low carbon floors in buildings owing to the low CO2 emissions from manufacture of the natural hydraulic lime constituent of limecrete. There are four novel facets to the present tests. First, an innovative rolling formwork was developed to facilitate casting of the two slabs needed per double-shear specimen. Second, the impact on connection behaviour of the inclination angles of the studs across the range 40–90°, in 10° increments, have been investigated. Third, the effects of either Ramin dowels or adhesive bonding to fasten the hardwood studs to the glulam blocks were studied. Fourth, these connections’ responses to multiple unload–reload cycles en route to failure were determined. The processed test data reveal the bonded stud connections to be of superior pullout and shear–slip properties to their dowelled stud counterparts, although the bonded stud connections did also exhibit significantly more pronounced variability in slip modulus than did the dowelled ones. Some hysteresis was displayed by all connections during load cycling, which is useful for energy dissipation. The bonded connections exhibited performance comparable to previously published connections based on inclined metallic screws threaded into spruce glulam and projecting into lightweight aggregate concrete. It is concluded that future tests to optimize these connection systems are warranted.

► Development of novel rotating formwork to cast two slabs per double-shear specimen.
► Use of bonded or dowelled studs as connectors between limecrete slab and glulam beam.
► Application of cyclic load at multiple stages en route to failure of each specimen.
► Output of test data to explain longitudinal shear mechanics of these novel connections.