Experimental research on seismic performance of precast cogging high-strength bolt composite joint and influence of its arrangement location

Abstract

The connection of precast joints is an important factor that affects the seismic and endurance performance of precast concrete structures. Currently, the seismic performance of existing precast joints cannot satisfy the application requirements of complex and harsh environments. This paper proposes a cogging high-strength bolt composite joint (C-HSB joint), and introduces its main components and assembly methods. Two precast beam-column joint (B-C joint) specimens are designed and manufactured using C-HSB joints. The C-HSB joints are arranged outside (SJ2) and inside (SJ3) the plastic hinge area of the beam. For comparison, a B-C joint specimen using a traditional cogging joint (T-C joint) is also designed and manufactured. The T-C joint is arranged outside of the plastic hinge area of the beam (SJ1). Then, quasi-static tests of these three specimens are performed. The seismic performance of the C-HSB and T-C joints are systematically analysed through the following parameters: damage phenomenon, bearing capacity, displacement ductility, rigidity deterioration, energy dissipation, operating state of the cogging seam, and bond-anchorage performance of rebar. Moreover, the influence of the arrangement location and HSB settlement of the C-HSB joint is discussed in detail. The results show that cogging can limit the development of seam cracks and improve the shear capacity of the joint. The HSB can delay the seam cracking, improve the bond-anchorage performance of rebar, and increase the crack resistance and self-resetting capacity of joints. The C-HSB joint can delay the development of seam cracks. The longitudinal rebar of the specimen can utilise more effectively using a C-HSB joint. The location of the C-HSB joint significantly affects the failure mode of the specimen. The internal arrangement (inside the plastic hinge area) of the C-HSB joint will induce the upward motion of the beam plastic hinge and exacerbate the core area damage. The external arrangement (outside the plastic hinge area) will increase the bearing capacity and energy dissipation of the specimens, and the rigidity deterioration will also be slowed. Compared with the C-HSB joint, the T-C joint has a lower displacement ductility, lower energy dissipation, and more rapid rigidity deterioration. The seismic performance of the T-C joint is significantly inferior. The C-HSB joint can be applied to precast concrete structures under complex and harsh environments. The external arrangement (close to the upper boundary of the plastic hinge area) of the C-HSB joint is a better choice.