دانلود رایگان مقاله انگلیسی ارتقای عمر لرزه ای برای سازه های زیرزمینی با معرفی یاتاقان ایزولاسیون کشویی - الزویر 2018

ABSTRACT

Isolation bearings have been a widely applied seismic strengthening technique in above ground structures. Whereas, the sliding isolation bearings were seldom used in underground structures. This study aims to explore the feasibility of sliding isolation bearings reducing the seismic response of underground structures. The collapse mechanism of underground structures was firstly analyzed by taking the Daikai Station as an example. Numerical results demonstrated that the collapse of the structure was due to the poor ductility of the intermediate columns. Therefore, the sliding isolation bearing could be installed between the columns and the beam to reduce the lateral deformations of columns. In order to determine an appropriate coefficient for sliding bearings, static analyses for the capacity of columns were conducted. Moreover, the performances of a beambearing-column system were also investigated. Finally, seismic responses of the underground structure retrofitted with bearings were studied. Numerical results presented that the responses of both columns and the whole structure were reduced remarkably. Moreover, the frictional coefficient of bearing influencing the seismic responses of underground structures was discussed. And some interesting conclusions were also obtained for the seismic design of underground structures.

Conclusion

In this study, the sliding isolation bearing was introduced to underground structures to enhance the anti-seismic capacity. Firstly, the collapse mechanism of underground structures was analyzed by taking the Daikai Station as an example. It was concluded that the collapse of underground structures originated from the poor ductility of columns at high normalized force state. Reducing the lateral deformation of columns was an effective approach to mitigating seismic damage of underground structures from earthquakes. Therefore, Pure-FrictionSystem bearings with low friction coefficient were installed in underground structures to assess the seismic performance of the retrofitted structures. Numerical results showed that the sliding bearing in the retrofitted underground structures worked well during earthquakes. The sliding of the bearing decreased remarkably the lateral deformation of the column when μ = 0.02. Consequently, the columns worked within their loading capacity, which makes the deformations of the lateral walls were also reduced. Therefore, sliding bearings is the effective device to improve the anti-seismic capacity of underground structures. In addition, the deformations of the whole structure and the components were all greatly influenced by the frictional coefficient, thus, to give an optimum range of the frictional coefficient is important for the design of bearings. In other words, the determination of the frictional coefficient is the key issue to keep the column stand straightly and to prevent the collapse of underground structures. Further, from this study, it can also be concluded that the technologies of seismic mitigation and isolation using in above ground structures can also be applied to underground structures for aseismic design.