The Seismic Performance of New Self-Centering Beam-Column Joints of Conventional Island Main Buildings in Nuclear Power Plants

Abstract

In order to improve the deformation energy consumption and self-centering ability of reinforced concrete (RC) frame beam-column joints for main buildings of conventional islands in nuclear power plants, a new type of self-centering joint equipped with super-elastic shape memory alloy (SMA) bars and a steel plate as kernel components in the core area of the joint is proposed in this study. Four 1/5-scale frame joints were designed and manufactured, including two contrast joints (a normal reinforced concrete joint and a concrete joint that replaces steel bars with SMA bars) and two new model joints with different SMA reinforcement ratios. Subsequently, the residual deformation, energy dissipation capacity, stiffness degradation and self-centering performance of the novel frame joints were studied through a low-frequency cyclic loading test. Finally, based on the OpenSees finite element software platform, an effective numerical model of the new joint was established and verified. On this basis, varying two main parameters, the SMA reinforcement ratio and the axial compression ratio, a simulation was systematically conducted to demonstrate the effectiveness of the proposed joint in seismic performance. The results show that replacing ordinary steel bars in the beam with SMA bars not only greatly reduces the bearing capacity and stiffness of the joint, but also makes the failure mode of the joint brittle. The construction of a new type of joint with consideration of the SMA reinforcement and the steel plate can improve the bearing capacity, delay the stiffness degradation and improve the ductility and self-centering capability of the joints. Within a certain range, increasing the ratio of the SMA bars can further improve the ultimate bearing capacity and energy dissipation capacity of the new joint. Increasing or decreasing the axial compression ratio of column ends has little effect on the overall seismic performance of new joints.

Bonding Mechanical Properties between SMA Fiber and ECC Matrix under Direct Pullout Loads

“…Therefore, superelastic SMA can be used in seismic structures to improve the energy dissipation capacity and provide self-centering capacity for structures. Pei et al [ 23 ] found that SMA bars were able to improve the bearing capacity, ductility, and self-centering capability of concrete beam–column joints. Cortés-Puentes et al [ 24 ] proved that the shear walls strengthened by SMA rods had a self-centering ability and were able to self-repair the damaged areas.…”

Construction applicability of mechanical methods for connecting aisle in the bohai mudstone stratum with high water pressure

“…established the discrete element model of connecting aisle excavation of the same size, and studied the surface settlement during shield excavation and the particle coordination number in the soil before the excavation. Many other scholars have also done a lot of work in the field of construction technology and risks of connecting aisle (Pei and Tao, 2011;Pei et al, 2013;Han et al, 2015;Li et al, 2015;Li et al, 2019;Wang et al, 2020a;Wang et al, 2020b;Wu et al, 2020;Yuan et al, 2020;Zhang and Zhong, 2020;Yuan et al, 2021a;Yuan et al, 2021b;Dai and Hu, 2021;Du et al, 2021;Ting et al, 2021;Wang and Meng, 2021;Zhang et al, 2021;Yuan et al, 2022a;Yuan et al, 2022b;Yuan et al, 2022c;Kun et al, 2022;Liu et al, 2022;Pei et al, 2022;Wang et al, 2022;Yang et al, 2022).…”

Shape Memory Alloys for Civil Engineering

“…The proposed approach was validated by experiments. Papers [ 2 , 3 , 4 , 5 ] focus on the applications of SMAs in braces and connections in residential buildings/industrial structures. Zhang et al [ 2 ] present a novel type of hybrid self-centering braces incorporating tension-only superelastic NiTi shape memory alloy (SMA) cables and integrated viscoelastic dampers (VEDs).…”

“…They have also developed improved numerical models combined with the Graesser and Bouc–Wen models in MATLAB. Pei et al [ 4 ] examine a new type of self-centering reinforced concrete (RC) frame beam-column joint, equipped with super-elastic SMA bars. It is shown that by using the SMA reinforcement and a steel plate, the load carrying capacity is improved, the stiffness degradation is delayed, and the ductility and self-centering ability of the joints is improved.…”

“…The above nine papers [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ] have focussed on NiTi SMAs. Iron-based SMAs (Fe-SMAs), also known as Fe–Mn–Si alloys, are another member of the family of smart metals for civil engineering.…”