Inclining Response Of The Multi-storey Building Subjected To Progressive Collapse Of Underground Structure Under Its Internal Blast Loading

In recent years, increasing issues of destroyed buildings which were caused by terrorist bombings and accidental explosion highlights the importance of establishing a structure with anti-explosion and explosion-proof. Once the underground structure was damaged by an accidental explosion, the whole underground structure may collapse, even structures on the ground may also be seriously destroyed. In this paper, the inclining response which is caused by progressive collapse of nearby underground structure through its internal blast loading will be demonstrated through analysing the frame structure with raft foundation, basement and pile foundation. The primary research work and achievements are summarized as follows:(1) ANSYS/LS-DYNA software will be used to establish underground structure-soil-multi-storey building on the ground (including the frame structure with raft foundation, basement and pile foundation) coupling models. Fluid-solid coupling methods will be applied to simulate explosion occuring inside the underground structure; three-stage analysis method presented in this paper is used to analyse the inclining response of the multi-storey building on the ground under the nearby underground structure explosion collapse, and then comparisons between the results through the proposed method, the alternative load path method and the direct simulation method are carried out; the approach proposed in this paper is proved to be reliable and efficient.(2) By analysing the inclining responses of the above three types of structures, it is found that the inclining response of the frame structure respectively with raft foundation and basement keeps a non-linear and rapidly rising trend along with the shortening of the horizontal space between the underground and the aboveground structures or the deepening of the underground structure's burial position(in comparison, the influence of the underground structure's burial depth is more remarkable); the inclining response of the frame structure with pile foundation under the nearby underground structure explosion collapse has a highly non-linear relation with the horizontal range between this structure and the underground structure. On the other hand, the bottom of column which is under the influence of progressive collapse of underground structure is the weakest part of the structures on the ground.(3). Through the comparative analysis of the inclining responses among the above three types of structures, it indicates that the anti-lateral performance of frame structure with pile foundation is better than the other two; the anti-lateral performance of frame structure with raft foundation is the worst. As for the frame structure with pile foundation, due to the reaction bwtween the pile foundation and the earth, the interaction leads great warping, the warping leads to the bottom column which is connected to pile foundation undertake high and uneven stresses.(4). According to the regulation of tilt value relates to code for design of building foundation, the degree of the inclining responses of the above three types of aboveground structures will be evaluated, then all of the aboveground structures discussed in this paper were divided into four safety levels as safety, general tilt, moderate tilt and serious tilt. And a safety scope for the horizontal space between these two structures and the burial depth of the underground structure is determined through the curve and formula generating from the data of conditions.This appproach provides a helpful reference for the research and design against this kind of disaster.