Numerical modeling and behavior of ductile short-grouted reinforcing bar-to-foundation connections for precast concrete structures

摘要

This paper presents the nonlinear finite element modeling and behavior of a short-grouted connection for ductile deformed steel reinforcing bars across gap-opening joints in seismic precast concrete structures. Uniaxial monotonic tension modeling of five previously tested ductile-bar connection specimens were conducted to: (1) analyze the different deformation components that contributed to the ductility of the connection in tension; and (2) investigate the effect of the connection sleeve taper angle and surface corrugations on the behavior of the connection. Straining of the connection bar had by far the largest contribution to the total joint separation (gap opening), while the grout-to-sleeve interface slip and grout deformation (straining) components had smaller but non-negligible contributions to the total joint separation. In comparison, bond slip of the bar had relatively small contribution to the joint separation. Increased taper angle of the connection sleeve provided more effective confinement of the grout by limiting the interface slip with respect to the sleeve and reducing the amount of cracking in the grout. The use of a straight, corrugated sleeve also reduced the slip (through interface friction), but also resulted in the largest grout deformations as compared with the tapered sleeves and more concentrated grout cracking in the top half of the connection. The largest tension stresses in the foundation concrete developed closest to the top of the connector, consistent with regions where hairline cracks were seen at the top of the foundation in the experimental program.