Experiment on seismic of Y-shaped assembled joints in subway station build by enlarging the shield tunnels
A Y-shaped assembled joint between shield segments and the main station structures was suggested in order to enhance the seismic performance of a subway station constructed by extending two parallel shield tun-nels.A 1∶1 full-scale model of two joints was used in experiments on low-frequency cyclic loading.The seismic behaviors,such as load-deformation curves,skeleton curves,structural ductility,strength degradation,and strain of the diagonal bars,were studied.The results showed that ① the shield segment separated from the steel plate,and the displacement of the B joint was greater than the A joint due to the differing constructions of the two types of joints.The residual deformation of the B joint and the pinch effect of the hysteresis loop were more no-ticeable;② as a result of the joint's inclined section,the hysteretic curve and skeleton curve both clearly dis-played asymmetries.B joint had greater bearing capacity,more consistent operating performance,better ductili-ty,and less stiffness deterioration during the entire loading operation;and ③ two different types of joints had dif-ferent energy dissipation mechanisms.The steel plate of the B joint had more stiffness than the A joint.The rein-forcement deformation of the B joint in the wall column was small,and the damage and deformation of the seg-ment's reinforcement and concrete caused most of the energy dissipation.However,because A joint was connect-ed by the connectors,the reinforcement on both sides deformed simultaneously,and the energy dissipation of A joint was rather higher than the B joint's.The failure of both of the joints was mainly because of the crushed seg-ment concrete,and the energy-dissipating capacity of the two types of joints was approximately the same.
enlarging station on shieldY-shaped assembled jointlow frequency cyclic loadingseismic per-formancehysteretic energy
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