Seismic performance of precast concrete column with different longitudinal reinforcement diameters under different lateral loading directions

Abstract

To improve the installation efficiency of precast concrete (PC) columns with grouted sleeve connections, increasing the diameter of longitudinal rebar but keeping similar reinforcement ratio is a solution. To quantify the effects of longitudinal reinforcement diameter on the seismic performance of PC columns, eight full-scale reinforced concrete columns (six PC columns and two cast-in-situ) with identical concrete strength, reinforcement ratio, and stirrup ratio were designed and fabricated. The longitudinal reinforcement diameters varied from 18 mm to 32 mm. Moreover, considering majority of existing tests on PC column were subjected to relatively low axial compression ratio due to limitation of test facilities. Low-cyclic reversed loading tests were conducted with a high axial compression ratio of 0.6. Furthermore, to evaluate the bilateral loading effects, the loading direction was either horizontal or diagonal. Test results showed that the PC column achieved even higher lateral load capacity than corresponding cast-in-situ column regardless of the loading directions. Moreover, the lateral load capacity of the column under diagonal loading is generally lower than that under horizontal loading. However, the ductility and energy dissipation capacity of the columns under diagonal loading were higher than those under horizontal loading. Increasing the diameter of the longitudinal reinforcement will increase the lateral load capacity of the PC columns. This is because increasing the diameter of the longitudinal reinforcement required larger size of grouted sleeve, which further shortened the effective length of the column due to plastic hinge shifting. However, increasing the diameter of the longitudinal reinforcement may require greater bond strength between rebar and concrete and aggravate the bond failure pre-mature, which resulted in the less of deformation capacity and ductility, as well as energy dissipation capacity.