دانلود رایگان مقاله انگلیسی ویژگی های پاسخ لرزه ای ساختمان سپری AP1000 هسته ای بر مبنای طراحی - الزویر 2018

abstract

Because of the design and construction requirements, the nuclear structures need to maintain the structural integrity under both design state and extreme earthquake shaking. The base-isolation technology can significantly reduce the damages of structures under extreme earthquake events, and effectively protect the safeties of structures and internal equipment. This study proposes a base-isolation design for the AP1000 nuclear shield building on considering the performance requirements of the seismic isolation systems and devices of shield building. The seismic responses of isolated and nonisolated shield buildings subjected to design basis earthquake (DBE) shaking and beyond-design basis earthquake (BDBE) shaking are analyzed, and three different strategies for controlling the displacements subjected to BDBE shaking are performed. By comparing with nonisolated shield buildings, the floor acceleration spectra of isolated shield buildings, relative displacement, and base shear force are significantly reduced in high-frequency region. The results demonstrate that the base-isolation technology is an effective approach to maintain the structural integrity which subjected to both DBE and BDBE shaking. A displacement control design for isolation layers subjected to BDBE shaking, which adopts fluid dampers for controlling the horizontal displacement of isolation layer is developed. The effectiveness of this simple method is verified through numerical analysis.

6. Conclusions

This paper designed a base-isolation system for the AP1000 NSB, analyzed the dynamic responses of isolated and nonisolated NSBs under the DBE and BDBE shaking, and compared the seismic characteristics of nonisolated and isolated structures. Considering the isolation layer under BDBE shaking, some advanced strategies were proposed for controlling the displacements of the isolation layer in the BI-NSB structure. The main findings are concluded below:

1. In high-frequency region, the base-isolation technology could significantly reduce the acceleration spectra of horizontal floor of NSB, and would exhibit a good seismic isolation effect both under DBE and BDBE shaking. The amplitudes of horizontal spectral acceleration spectra could be reduced at least 80%. In low-frequency region, the acceleration spectra of horizontal floor of isolated NSB are higher than those of the nonisolated NSB. However, the value of floor acceleration is sufficiently small in low-frequency region, and could be neglected.

2. By comparing the horizontal displacements and base shear forces of the isolated and nonisolated NSBs subjected to DBE and BDBE shaking, the deformations of the isolated NSB are mainly concentrated in the flexible isolation layer, and that the relative displacement of the upper structure is extremely small and can be significantly reduced in comparison with that of the nonisolated NSB. Because of the base isolation, the isolated NSB experiences markedly reduced shear force in the isolation layer, and the base-isolated system could still exert a satisfactory control subjected to BDBE shaking.

3. Considering the excessive displacement of the isolation layer under BDBE shaking, we proposed three strategies to control isolation layer displacement, and presented a damping devicebased method of displacement control design for the isolation layer. It also presented the steps for designing the isolation layer displacement control for NSBs subjected to BDBE shaking, and verified the effectiveness of adopting fluid dampers for controlling the displacement of the isolation layer.