| The collapse of Daikai subway station during the 1995 Kobe earthquake in Japan has aroused widespread concern about the seismic performance of underground structures.Taking the collapsed single story and double span structure section as the research object,researchers have studied the seismic response characteristics of underground structures and revealed their failure mechanisms through seismic investigation,model tests,and numerical simulation methods,and developed corresponding seismic performance upgrading methods and technologies.However,most subway station structures in China are more complex than Daikai station,and these structures have not experienced strong earthquakes.The seismic performance and failure modes of structures are still unclear,leading to a lack of basis for improving their seismic performance.Therefore,conducting research on the seismic performance of complex subway station structures,identifying potential failure modes of structures and revealing their failure mechanisms,combining with the concept of seismic resilience design,and developing seismic resilience upgrading techniques for underground structures have guiding significance for improving the seismic resistance and disaster reduction capabilities of underground structures.The main achievements of the paper include:1.Comprehensive evaluation indexes for horizontal and vertical seismic performance of underground frame structures were established.The potential failure modes and failure mechanisms of a subway station structure with doublelayer and different spans was revealed.Based on the resilience concept,seismic resilience upgrading methods of underground structures were proposed.Seismic performance evaluation indexes for underground frame structures were established that comprehensively considers the interlaminar deformation capacity of columns and sidewalls and the flexural deformation capacity of slabs.Seismic performance upgrading method of complex subway station structures based on controlling potential failure mode was proposed.The seismic response analysis of underground structure with double-layer and different spans was carried out,and the structural seismic performance was evaluated using the proposed evaluation indexes.The potential failure mode and failure mechanism of the structure was revealed.The seismic performance upgrading scheme of the structure was formulated,and its effectiveness was verified.Based on the seismic research results of Daikai station structure and structure with double-layer and different spans,combined with the resilience concept,the idea and method for upgrading seismic resilience of underground frame structures were proposed.2.A seismic resilience upgrading technique for underground frame structures,Segmental Cored Column(SCC),was proposed.The working mechanism of SCC was revealed,and effectiveness of SCC for upgrading seismic resilience of underground structure was verified.According to the failure mechanism of underground structures and the resilience upgrading method,a novel column type,Segmental Cored Column(SCC),was designed.SCC can improve the interlaminar deformation capacity of columns without reducing its vertical bearing capacity.The analytical analysis of the stress-deformation relationship of SCC was carried out,the deformation mode and working mechanism of SCC were clarified,and the horizontal load-displacement relationship of SCC under different axial compression ratios was established analytically.The deformation capacity envelope of SCC is obtained as its seismic performance evaluation index.The key parameters affecting the interlaminar deformation capacity of SCC were analyzed.Pushover analysis and seismic response analysis of a single-story double-span structure(configured with SCC and normal RC columns)were performed.The upgrading effect of SCC on the seismic resilience of frame underground structure was verified.3.Seismic resilient structure,i.e.,arch roof patially prefabricated structure,was designed.Numerical simulation method of mortise-groove joints was established.The effectiveness of prefabricated arched roof in improving the seismic resilience of double-layer and double-span underground structures was verified.The structural design method of arch roof patially prefabricated structure was proposed.The assembled arch roof is used to distribute more vertical loads to the sidewalls with stronger vertical bearing capacity than columns,ensuring that the vertical bearing requirements and vertical bearing capacity of columns and sidewalls match,thereby improving the seismic resilience of underground frame structures.The advantages of partially prefabricated structure were expounded from the perspectives of structural construction,waterproof design and seismic design.The numerical simulation methods of mortise-groove dry joints and grouting joints were proposed,and the 3D seismic response analyses of the partially prefabricated subway station structure and cast-in-place structure were carried out,which verified the seismic resilience advantages of the partially prefabricated structure. |
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