Quasi-static experimental study on full-scale prefabricated bridge pier of Beijing-Xiong'an transit express line
The prefabricated vase-shaped bridge piers with hybrid connections of unbonded prestressed tendons,grouted sleeves and concrete shear keys were used in the section from Bazhou development zone station to Yongqing station of Beijing-Xiong'an transit express line(Line R1).In order to examine the reliability of seismic design for prefabricated bridge piers in high-intensity seismic regions,the first quasi-static full-scale test in the world on the 10000 ton-capacity multi-functional testing system was carried out.The damage development process and eventual failure mode of the pier under horizontal cyclic loads were discussed.The seismic performances,including hysteretic performance,displacement ductility,deformation distribution characteristics and local material mechanical behavior,of specimen were quantitatively analyzed.The results show that,the prefabricated bridge pier with hybrid connections exhibits the typical flexural failure mode of forming plastic hinge at the grouted sleeve area of pier bottom,and the damages occur in the sequence,namely cracking of pier concrete,yielding of longitudinal reinforcements at the bottom and top of grouted sleeve of pier bottom,spalling of concrete protective layer at grout outlet,fracture of outermost longitudinal reinforcement,and crushing of a little core concrete.Under the biaxial loading,the hysteresis curve of bridge pier appears to be the shape of parallelogram,and the maximum bearing capacity in the transverse direction of bridge is 4749.88 kN;while under the unidirectional loading,the longitudinal hysteresis curve of bridge pier appears to be the shape of bow with obvious pinching.The maximum bearing capacity in the longitudinal direction of bridge is 3773.50 kN,and the displacement ductility coefficient is 2.75.Furthermore,the curvature at the joint of pier bottom is the largest,followed by that at the pier shaft,and that at the joint of pier neck is zero.Meanwhile,the shear deformation at the joint of pier neck is about 0.15mm,which however can be basically ignored.Finally,the unbonded prestressed tendons shall be always in elastic state during the loading process,indicating the reliable performance of hybrid connections.The research results can be referred to when applying this type of bridge pier to the projects with similar site conditions.
transit express lineprefabricated bridge pier with hybrid connectionsfull-scale modelquasi-static testseismic performance10000 ton-capacity multi-functional testing system
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