Experimental investigation on the behavior of grouted restrained anchor connections for cluster-reinforced precast concrete columns

Quality, safety, and construction efficiency of assembled buildings are closely related to the connection between precast components. However, the traditional connection technique requires a high number of reinforcing bars, resulting in inefficient installation. The present paper proposes using a bundle of small-diameter reinforcing steel bars instead of multiple bars or larger bars arranged in the column. Therefore, the connection number of vertical steel bars is reduced, and the anchorage length of steel bars in the precast member is shortened so that the assembly is simplified and installation efficiency is enhanced. This paper also presents the results of cyclic loading tests and finite element analyses on precast concrete columns with semi-grouted and full-grouted restrained clustered bars. The purpose is to investigate the effects of anchorage length and tensile strength of vertical steel bars, axial compression ratio, and other parameters on connection performance to ensure adequate structural performance. It was found that both the full-grouted and semi-grouted restrained connection of tensile steel bars can transfer stress effectively. It will be also shown that these connection methods of vertical steel bars are suitable for precast concrete columns.