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The PBL (Perfobond Leiste) shear key has advantages such as high load capacity and high restraint capacity. However, at the same time, there are also problems such as insufficient deformation capacity and low stiffness along the weak axis direction. In addition, shear key performance degradation, ductility, and other problems are not yet clear under the reciprocal seismic action. To this end, a folded perfobond shear key is proposed in this paper to solve the problems of insufficient deformation capacity and uneven stiffness distribution of the traditional PBL shear key. At the same time, numerical analysis is carried out to investigate the seismic performance of the shear key under earthquakes, such as stiffness degradation, ductility, and energy dissipation. Through the push-out test, it is found that the steel plate outside the shear key deforms, showing a certain semi-rigid characteristic; concrete forms a trapezoidal constraint area centered on shear keys, and the constraint effect is significantly improved compared with the point constraint of studs. On the whole, under the condition of a similar shear section, the bearing capacity of the shear key is 1.5 times that of the stud. The ductility coefficient is above 3.0, showing good deformation ability. Through parameter analysis, it is found that the bearing capacity of shear keys increases with the increase of web width-thickness ratio, but the deformation capacity degenerates. The opening rate mainly affects the embedded effect of shear keys and concrete. Based on the fitting analysis, the variation laws of web width influence coefficient γB, web height influence coefficient γH, and embedded effect influence coefficient γDare obtained, and the calculation formula of shear key bearing capacity is proposed. Finally, based on the push-out test, the hysteretic behavior of the shear key is studied. It is found that the load-displacement hysteretic curve of the shear key is full, the ductility coefficient is 4.2, and the equivalent viscous damping coefficient is 0.27, which shows good seismic capacity. In summary, the new shear key realizes the good unity of bearing capacity and deformation and has high engineering application value.

Coupling beams of coupled shear wall system in seismic regions are required to have high load resisting capacity and excellent ductility and energy-dissipation capacity. To achieve this goal, the concept of steel-concrete composite coupling beam is proposed. The steel-concrete composite coupling beam is a new form and worthwhile to research and promote. Further, it is a new direction for the future development of the coupling beam. But there is a lack of specific calculation method and constructional measures in the current related codes. In this paper, the review of available literatures is made including the experimental study and influence factors of mechanical behavior. It works that have not yet been covered after summarizing each research methods and research contents, which will provide scientific reference material for the intensive research on steel-concrete composite coupling beam.

A 3-D finite element model (FEM) using ABAQUS was established to simulate the performance of the composite joints with reinforced concrete column and steel beam. Accurate material model, element type, and solution method were discussed in the model. The results from FEM are good agreement with the test results. Some composite joints, reinforced concrete (RC) column to steel beam were modeled based on the model. The mechanism of the composite joint was investigated based on the FEM.

Patients receiving maintenance hemodialysis (MHD) are highly vulnerable to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The current study was designed to evaluate the prevalence of SARS-CoV-2 infection based on both nucleic acid testing (NAT) and antibody testing in Chinese patients receiving MHD.