Numerical study on mechanical and adhesive splices for ribbed GFRP plates used in concrete beams

A new concrete beam design, comprising concrete core and glass fiber reinforced polymer (GFRP) ribbed side plates has been developed. Plate splicing is made by using a mechanically fastened or adhesively bonded spliced form through end ribs. This paper presents the development, calibration, and application of comprehensive finite element models for the hybrid beam. The models incorporate material and geometric nonlinearities along with bond-slip interfacial relations. Interfacial behavior at the plate-to-plate splice, whether adhesively bonded or mechanically fastened, as well as plate-concrete interface are considered. Parametric study was performed to examine the effects of fastener spacing and adhesive coverage length of the 4 mm thick GFRP plates. It was shown that the ultimate strength of beams with adhesively bonded splices was 28% higher than the beams with unbonded splice (i.e. without any adhesive or fasteners). Decreasing fastener spacing from 47 to 3.8 times the fastener diameter resulted in increasing ultimate load by about 20%. No further reduction in load occurs beyond fastener spacing larger than 47 times the diameter. The beam stiffness at service load is not affected by the fastener spacing or the adhesive coverage length.