Damage control of a twin-column pier with a replaceable steel shear link in a cap beam under transverse seismic motion

This paper proposes a novel twin-column pier with a steel shear link (SSL) installed in the cap beam to reduce seismic damage in the transverse direction. The SSL interrupts the rigid cap beam and relieves the coupled deformation of the two columns. Benefits of the yieldable SSL in the event of a strong earthquake are the longer effective deformation of a column and limited axial compressive load. A benchmark reinforced-concrete bridge is employed in a seismic performance evaluation to verify the damage reduction performance of the novel twin-column pier with an SSL. Five numerical models, calibrated in a physical component test, are built in ABAQUS; that is, one original bridge and four novel bridges with different SSLs and accompanying configurations. Modal analysis shows that introducing the SSL does not change the overall structural dynamic characteristics. The nonlinear dynamic analysis results indicate that adopting the SSL effectively reduces the peak compressive strain of the reinforced-concrete column, but energy dissipation from the SSL is negligible compared with the total inputted seismic energy. There is no evident change in the macro seismic response of the twin-column pier when using the SSL, such as overall drift and structural damping ratio. Moreover, a transverse continuous main girder is suggested for realizing an additional restoring moment at the column top, which further reduces compressive strain.

Seismic Performance Evaluation of Precast Concrete Beam-to-Shear Link Composite Connection with Bending Moment and Shear Force Separate Method

A new type of prefabricated reinforced concrete-Y-shaped eccentrically steel brace structure (PRC-Y-ESBS) is developed by combining the mechanical property of prefabricated reinforced concrete frame and Y-shaped eccentrically steel brace, so the seismic performance and seismic resilience capacity of prefabricated reinforced concrete frame can be effectively improved. In the PRC-Y-ESBS, the precast concrete beam-to-shear link composite connection should have enough bearing capacity and resilience capacity under the shear force and bending moment, so the damage can be restricted in shear links. In this paper, an innovative precast concrete beam-to-shear link composite connection (PCB-SLCC) with bending moment and shear force separate method is proposed. Four different types of shear connectors are analyzed in detail by using the verified numerical method, and the shear capacity and failure mode of shear connectors can be obtained. Then, the innovative PCB-SLCCs with the reasonable shear connector considering different influencing parameters are also studied in detail. The results indicate that the shear connectors and high-strength bolts are still in elastic state at ultimate load, and little damage has occurred in the concrete between the embedded plate and precast concrete frame, while the PCB-SLCC has enough bearing capacity at the ultimate stage. In addition, this study also clearly identifies that high-strength bolts can only bear the bending moment, and the shear force is only carried by shear connectors, so the bending moment and shear force of the innovative PCB-SLCC with high bearing capacity, ease of installation, and seismic resilience capacity can be apparently separated.