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The vertical component of ground motions can affect the seismic performance of reinforced concrete (RC) piers as significant as its horizontal counterpart. However, real‐time testing for RC piers subjected to both horizontal and vertical ground motions has been scarcely conducted due to the difficulty in multi‐axial control of actuators. In this study, the seismic response of a bridge RC pier was investigated by conducting real‐time hybrid simulation (RTHS), where the RC pier was physically tested in the laboratory and the bridge superstructure was numerically modeled. The test setup that can synchronously apply both horizontal and vertical ground motions was constructed by using three dynamic actuators and a flexible loading beam (FLB). The lateral response of the RC pier was investigated by varying the intensities for vertical ground motions, while the same intensity for horizontal ground motion is used. It was found that the axial force from the dead load of superstructure can significantly affect the initial stiffness, strength, and post‐yield response of the RC pier. For the selected earthquake ground motions, however, the intensity of vertical ground motion did not make a substantial difference in the lateral response, although there was a notable difference in the fracture pattern. [ABSTRACT FROM AUTHOR]

There has been growing interest in seismic hazards in permafrost regions as development in those regions has increased. Because major infrastructure, such as natural gas pipelines, has been constructed in permafrost regions, it is necessary to evaluate the seismic safety of such a network system. As frozen soil's dynamic properties differ from those of its unfrozen state, the characteristics of seismic waves propagated through frozen soil layers in permafrost differ from those propagated through unfrozen soil. Thus, the dynamic properties and composition of frozen soil layers located between bedrock and the ground surface need to be realistically considered in evaluating the seismic hazards of permafrost regions. The frozen soil layer's composition greatly depends on soil temperatures which vary seasonally and are gradually increasing due to global warming, therefore it is necessary to consider soil temperature variation. In this study, comprehensive parametric site response analysis was carried out based on measured data regarding seasonal and annual temperature variation to investigate seismic hazards. The soil temperature variation between summer and winter and temperature increases due to global warming were the main considerations. The analysis results clearly show that the soil temperature variation significantly impacts seismic hazards in the permafrost region, leading to different site response characteristics than those in the non‐permafrost region. [ABSTRACT FROM AUTHOR]

Summary: In a building subjected to seismic loading, large compressive force may develop in reinforced concrete (RC) coupling beams because of axial restraint imposed by the neighboring shear walls against the elongation of the coupling beams during the failure process. The axially compressive force can increase the shear stiffness and strength of the coupling beam and may change its failure mode. In this paper, a novel coupling beam testing procedure adopting hybrid simulation method is proposed in which the axial restraint is determined through hybrid simulation and the calculated axial restraint is imposed on a specimen during the test. RC coupling beams were tested by adopting both the proposed test procedure and the conventional testing approach in which the effect of the axial restraint is not accounted for. Test results depict a clear difference in the response of the coupling beam, such as shear capacity and failure mode, depending on the consideration of the axial restraint during the test. The test outcome demonstrates the usefulness and applicability of the proposed test procedure. [ABSTRACT FROM AUTHOR]