Multifunctional all-GFRP joint for concrete slab structures

An existing hybrid-GFRP/steel joint for load transfer and thermal insulation in concrete slab structures was developed into an all-GFRP joint. The new joint consists of a pultruded GFRP tensile/shear element anchored through adhesively bonded ribs in the concrete and a compression/shear element with contacting cap-plates. The new joint improves considerably the energy savings of buildings due to the low thermal conductivity of GFRP composites. The quasi-static performance of the new joint was investigated through full-scale experiments on cantilever beam elements and analytical modeling. The all-GFRP joint provides ductile performance similar to the hybrid-GFRP/steel joint. The transfer of bending moments occurs through tensile forces in the upper flange of the tensile/shear element and compression forces in the lower flange of the compression/shear element. The shear force transfer is shared between both GFRP elements. The tensile/shear element attracts 50% more shear force due to the fixed end supports. Simple analytical models can be used to describe the joint behavior and compare well with measurements.