The Progressive Collapse Resistance Mechanism of Conventional Island Shield Buildings in Nuclear Power Plants

In China, conventional island shield buildings (CISBs), which are situated close to the nuclear islands of power plants, class III seismic items. This is most important level in fortification standard. Calculations check resistance overturning under extremely safe action should be carried out. Although strict design has been out, many beyond-design-basis events, such as 3/11 earthquake Japan, have occurred recent years. Under accidental loads, there still possibility that vertical bearing components a CISB will damaged or destroyed, lead progressive collapse structure, and ultimately threaten operation plant. Therefore, it necessary study mechanism order further optimize improve its design. this paper, we take research object consider failure synthetically, using SAP2000 finite element software causation strength force internal redistribution characteristics due different column removal conditions (long-side middle, short-side internal, corner columns) instantaneous unloading method. The results show residual structure at risk long-edge middle conditions, no short-edge conditions. only beam mechanism, long-side forms catenary Y direction. can resist by while bidirectional X directions. axial mainly redistributed members with adjacent spans column, separated less affected.