Beam-column joints in continuous RC frames: Comparison between cast-in-situ and precast solutions

The use of precast reinforced concrete elements is rapidly increasing since this technique has several advantages over traditional cast-in-situ structural members such as lower manufacturing time and costs and a better quality control. Nevertheless, cast-in-situ solutions intrinsically allow building moment-resisting frames, a behavior that is usually hard to achieve using precast elements. In this paper a technical solution able to offer both high strength and ductility, simplicity of construction of the prefabricated elements and ease of assembly on site is presented. The solution realizes the continuity between beam and column by means of loop splices and cast-in-place concrete with steel fibers to improve the ductility of the concrete struts in the wet joint. The connection has been experimentally tested and compared to an analogous cast-in-situ one. The experimental results confirmed its good structural performances in terms of strength and ductility. Numerical investigations tuned on the basis of the experimental results allowed the improvement of the design to achieve reduced column damages for higher drift values while maintaining practically unchanged structural performances.