Seismic performance of concrete-filled hollow precast concrete columns with prefabricated inner mold

In this experimental study, cyclic loading tests were conducted to evaluate the seismic performance of concretefilled hollow precast concrete (PC) columns (HPCC) manufactured using an inner mold composed of shear studs and louver plates. Both shear studs and louver plates were employed to ensure the structural integrity between the old concrete (outer shell) and new concrete (cast-in-place concrete). The hollow ratio of the test specimens fabricated using the inner mold was 22%. Up to a drift ratio of 3.0%, the hysteresis loops, yielding stiffnesses, and dissipated energies of the hollow column specimens were nearly identical to those of the monolithic columns. Beyond the peak strength, the hollow specimens—monolithically connected to the foundation—exhibited a lower hysteresis loop, dissipated energy, and displacement ductility ratio than the monolithic column specimens; this trend was more pronounced in the PC specimens with sleeve connections. The strain histories of the longitudinal bars of all the specimens were nearly identical, regardless of the presence of a hollow section. All the column specimens exhibited a measured peak moment exceeding the nominal peak moment in accordance with the ACI 318 standard. Overall, the HPCC specimens fabricated using the proposed prefabricated inner mold exhibited structural behavior similar to that of conventional RC columns.