Experimental study on flexural behaviour of prefabricated concrete beams with double-grouted sleeves

Abstract A novel precast concrete beam connected using double-grouted sleeves was developed to reduce pouring concrete on-site and expedite construction. This paper presents a systematic experimental study on the flexural behaviour of precast beams subjected to three-point and four-point bending. In total, 11 specimens with different types of grouted sleeves, diameters of the lower transition bar, filler lengths, numbers of filler, types of filler, types of connection and lengths of the grouted sleeve, and two cast-in-situ specimens were tested. The results indicated that the steel sleeves in the beams performed satisfactorily, and threads aided in increasing their initial stiffness. The first cracking load of all the prefabricated beams was lower than that of the reference beams owing to the interface effect. With an increase in the diameter of the lower transition bar, the yield and ultimate bearing capacities of the precast specimen under three-point bending increased by 9.0% and 21.0%, respectively. The beams with double-grouted sleeves exhibited better ductility with maximum crack widths that were 41.2% and 28.6% larger than that of the reference beam under three-point and four-point bending, respectively. The stress concentration in the filler region occurred owing to discontinuous stiffness but decreased with an increase in the diameter of the lower transition bar. The beam with double steel sleeves achieved a slightly lower normal service load limit than the cast-in-place beam. As the filler length increased by 20 mm, the maximum crack width of the beams with double-grouted sleeves increased by 55.6%. The method for the cast-in-place beam was adequate for calculating the load-bearing capacity of the prefabricated beam with double-grouted sleeves or a single-grouted sleeve.