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In this study, seven one-third-scale bridge column specimens are tested via a quasi-static cyclic test to understand seismic performance differences between cast-in-place (CIP) and precast bridge columns with various shear span-to-depth ratios and connection design details. The columns are designed based on practical engineering application, which aims to provide design reference for the seismic behavior of real-world bridge structures with varying column heights, such as bridge ramps. Based on the test results, it was found that column height exceeding the plastic hinge region is of combined bending and shear failure and that the full development of the plastic hinge region of these columns yields the same damage progression. However, short columns that are lower than the height of the plastic hinge are subjected to pure shear failure, and they are also of the same level of seismic performance except for displacement-related indices. Though the strengthening effect of the grouted splice sleeve connections is observed and damage is more concentrated at the joint for precast bridge columns, the difference of overall seismic performance between CIP and precast bridge columns is less than 5% in terms of ductility and energy dissipation. The addition of shear keys or change of bond material help improve the structural integrity, while the increase of seismic performance is still limited. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, six 1/3-scale short bridge column specimens are investigated for shear strength under the same quasi-static cyclic loading protocol. The specimens consist of one cast-in-place (CIP) reference column and five precast columns, and the precast columns are designed with different connection approaches. The test includes the comparison between the specimens with or without shear keys, bonded or unbonded prestressing tendons, and column or footing embedment. Test results show that the shear strengths of precast columns using only mild reinforcement are emulative of the CIP column. Shear keys employed in the connection do not retain significant improvement in terms of hysteretic behavior, while specimens with prestressing tendons possess higher shear strength but lower ductility. The unbonded prestressing tendon provides unique self-centering capability with good energy dissipation. Finite element models of the columns were created with ANSYS by considering the bond-slip effect between reinforcement and concrete, contact behavior of connection surface, and material nonlinearity, depending on different structural details. The models can effectively simulate damage development under monotonic loading, and the load-displacement curves are in good agreement with the backbone curves of the test results. [ABSTRACT FROM AUTHOR]

In this study, seven 1/3-scale bridge column specimens are investigated under the same quasi-static cyclic loading protocol both experimentally and numerically. The specimens consist of one cast-in-place (CIP) reference column and six precast columns. The precast columns are designed with different connection details, and they are tested for the feasibility study of the urban viaducts of highway S6 in Shanghai, China. The seismic performance of the precast columns needs to be investigated and verified prior to the practical application of these connection designs. Based on the experimental results, the precast specimens solely using mild reinforcement exhibit similar hysteretic behavior to the CIP reference column, though various grouted connection approaches are employed. The differences between these precast specimens and the CIP reference column are less than 15% for all indices. The precast specimens with bonded tendons (prestressing strands or prestressing bars) retain higher strength, but no less than 30% decrease of energy dissipation capacity is found. The bonded prestressing strands give at least 10% increase in strength compared with the CIP reference column, while the bonded prestressing bars provide approximately 50% improvement. The precast specimen utilizing unbonded tendon (prestressing strands) shows unique self-centering capability with equivalent energy dissipation capacity of the CIP reference column, but it has 33% lower ductility. Finite element modeling is performed and calibrated with the test data. Bond-slip behavior near column-to-footing interface is modeled by using a ZeroLength element at the interface. Buckling, fatigue and strength reduction of reinforcement are also considered in the model. Hysteretic behaviors of the specimens can be effectively simulated, and differences of ultimate strengths between the experimental and numerical results are less than 9%. [ABSTRACT FROM AUTHOR]

In this study, quasi-static cyclic test was conducted for three 1/3-scale specimens of different precast concrete frame pier structure systems of an urban viaduct in Shanghai, China. Various connection deployment strategies were utilized for the specimens, in order to verify these precast concrete frame piers used in the real structure. Two of the specimens were of the same cap beam design, while the third one was with tie beam. The two frame piers with cap beam had the same column-footing connection (grouted splice sleeve coupler), but the column-cap connections were grouted splice sleeve coupler and grouted corrugated duct connection, respectively. The frame pier with cast-in-place tie beam, however, only kept the grouted splice sleeve coupler for column-footing connection. The cyclic test results showed similar seismic behavior of the two specimens with cap beam, whereas the specimen with tie beam exhibited less energy dissipation capacity. This indicated that the seismic performance differences among the specimens are mainly caused by different structure systems, and the two types of the connections behave similarly with little damage. Finite element models that were optimized by considering joint region behavior and bond-slip phenomena showed good agreement with the test results. [ABSTRACT FROM AUTHOR]

With the increasing utilization of fiber-reinforced polymer (FRP) bars in concrete structures, the issue of retrofitting damaged FRP-reinforced concrete (FRP-RC) structures will emerge. However, limited research is available on the seismic performance of damaged FRP-RC structures after retrofitting. In this study, cyclic tests were conducted to evaluate the efficiency of precast ultra-high performance concrete (UHPC) plates in retrofitting the seismic performance of GFRP-RC columns with continuous or lap-spliced GFRP bars. Three GFRP-RC columns, among which one column with lap-spliced details was strengthened with precast UHPC plates, and the other two columns were retrofitted with precast UHPC plates combined with NSM after simulated seismic damage testing. To compare the retrofitting efficiency of this method for GFRP-RC and steel-RC columns, a previous study on steel-RC columns retrofitted with UHPC was incorporated. For the pre-damaged GFRP-RC columns after retrofitting with precast UHPC plates combined with NSM, the peak load experienced an increase of 76 %–79 %, and the ductility was complete restored. The failure modes of strengthened or retrofitted GFRP-RC columns differ from those of strengthened or retrofitted steel-RC columns. Further, the flexural strength of GFRP-RC columns and beams after being strengthened or retrofitted by UHPC can be predicted well based on the cross-section analysis model. • Cyclic behavior of pre-damaged GFRP-RC columns retrofitted with UHPC was investigated. • The seismic performance of GFRP-RC columns was significantly improved after retrofitting with precast UHPC plates. • The design method accurately predicts the flexural strength of GFRP-RC columns and beams strengthened with UHPC. [ABSTRACT FROM AUTHOR]

Pile-slab bridges with prestressed high-strength concrete (PHC) piles or prestressed and reinforced high-strength concrete (PRC) piles are widely used in low-seismic zones. To further understand the seismic performance of pile-slab bridges and to promote their applications in high-seismic regions, specimens of PHC bent (PHCB) or PRC bent (PRCB) from pile-slab bridges with a new bent-cap-pile pocket connection are studied through quasi-static cyclic tests. Seismic performance of the PHCB and PRCB is evaluated and compared in terms of damage development, failure mode, lateral stiffness, residual displacement, peak strength, displacement and energy-dissipation capacity. The experimental results show that both PHCB and PRCB fail due to non-ductile fracture of prestressing rebars in the piles, and the proposed bent-cap-pile pocket connection remains functional throughout the tests. Additional mild rebars of PRCB significantly increase displacement capacity of PRCB against PHCB. Finite element (FE) models are then developed and validated by the experimental results, after which the influence of initial prestressing force level and longitudinal prestressing reinforcement ratio of piles is investigated through parametric study based on the validated models. The proposed FE models can accurately predict the overall hysteretic behavior. Based on the parametric study, the seismic performance of both PHCB and PRCB can be improved by decreasing initial prestressing force level or increasing longitudinal prestressing reinforcement ratio. • Seismic performance of pile-slab bridge bents with a new bent-cap-pile pocket connection design is investigated. • Damage development and test data of pile-slab bridge bents with different pile types are compared and discussed. • Nonlinear finite element models for the proposed pile-slab bridge bents are developed and verified. • Influence of prestressing reinforcement on the seismic performance of pile-slab bridge bents is parametrically studied. [ABSTRACT FROM AUTHOR]