In this study, four 1/3-scale bridge column specimens were investigated both experimentally and numerically. The specimens consisted of two cast-in-place (CIP) reference columns and two precast columns for the study of socket and pocket connections, respectively. The precast columns were designed based on the actual application of precast urban viaducts in Shanghai, China. Therefore, this study investigated and verified the seismic performance of these connection approaches. Based on the test results of the hysteretic behavior and derived indexes, both columns with socket and pocket connections have shown equivalent seismic performances to their CIP references. The differences between precast and CIP columns were within 15% for all indexes, and the damage development and failure mechanism were also similar. Finite-element models were created with displacement analyser (DIANA) and calibrated with the test data. Bond-slip behavior with the built-in embedded reinforcement element, concrete cracking with tension softening, and material nonlinearity were considered. Under monotonic pushover analysis, the load-displacement curves were in good agreement with the backbone curves of the test results.

Corrosion-induced bond degradation of deformed steel rebar in concrete is experimentally investigated with acoustic emission (AE) and 3D laser scan technique. Concrete specimens were fabricated and subjected to direct pullout test after being corroded to different levels. The number and width of cracks present during the corrosion tests and the pull-out tests were recorded. The energy released during the pullout tests were captured with AE probes, and the frequency characteristics was analyzed. After pullout tests, the surface morphology of corroded steel rebars was determined with a 3D laser scanner. A modified bond deterioration model was proposed and the parameters associated with the model were analyzed. Results indicated that two types of AE signals were acquired during pullout tests: concrete cracking in high frequency range of 35 ~ 41 kHz and steel-concrete friction in low frequency range of 3 ~ 15 kHz. The bond strength and the bond-slip characteristics depend upon the level of corrosion as well as the number and width of cracks. The reduction factor of the bond-slip model exponentially decreases as a function of the average cross-sectional area loss and linearly decreases with an increase of the rib area loss.

This study introduced a new design of the grouted corrugated duct connection (GCDC), which improves the structure integrity, bond strength and ease of constructability. A two-phase experimental program was performed to fully understand the connection behaviour. Phase I focused on the pull-out tests of 32 specimens in two batches with various conditions. It indicates that a connection length of 30 times of the rebar diameters would guarantee the bond strength. Phase II compared the 1/3-scale precast bridge column with its cast-in-place reference via quasi-static cyclic test. It showed that the precast column behaved similarly to that of the CIP column.