Cyclic Loading Test of Unbonded and Bonded Posttensioned Precast Segmental Bridge Columns with Circular Section

Abstract

Four 1/4-scale precast segmental bridge columns (PSBC) with different reinforcement types and arrangements and one monolithic reference column (MRC) were designed and tested under cyclic quasi-static loading. Both UPC (PSBC with unbonded tendons only) and UPCE (PSBC with unbonded tendons and bonded mild steel bars) use unbonded posttensioned (PT) strands to connect the segments. Bonded energy dissipation (ED) bars were added in UPCE to increase the ED ability of unbonded PSBC. Specimens BPC (PSBC with fewer bonded PT bars) and BPCII (PSBC with more bonded PT bars) use bonded PT bars to combine the segments together. The unbonded length was set in ED bars to delay the low-cycle fatigue damage. Test results showed PSBC only has minor concrete cracks or crushing at lower joints. The unbonded PT PSBC with ED bars had higher lateral strength, lower residual drift, and comparable ED with MRC. The bonded PT bar PSBC with appropriate bar arrangement also showed high lateral strength and medium energy-dissipation ability. However, bonded PT PSBC experienced large PT stress loss, which leads to a residual drift of 3% when unloading from 6% drift.