| Buildings on the slope have varying degrees of application in mountain cities andplain areas. From perspective of structural design, their mechanical properties aredistinct from of the general structures while there are neither available specifications tofollow nor many researchers being engaged in such field. Moreover, most of theachievements are originated from elastic analysis and few studies are concerning theelastic-plastic behavior or failure mode of mountain structures during rare earthquake.In fact, as a kind of typical structure in mountain buildings, SSFDH means a variety ofRC frame structure supported by foundations with different horizontal levels which thefloors below are being set by story height according to the upmost ground point. In thispaper, the author develops analysis on the failure mode of SSFDH during rareearthquake and focuses on the failure mode and the relative affecting factors of SSFDHswhich are designed in accordance with current design codes.This paper describes the characteristics of the mountain buildings, shows how thenumerical example being designed, analyzed and also emphasizes the selection anddetermination of analytical parameters. In addition, the dynamic elastic-plastic timehistory analysis is being performed in OpenSees with refined finite element modelcomposed of fiber models and flexibility-based elements, and also the authorinvestigates how the number of off-layer floors and spans impacting on the location ofdamage, sequence of failure and levels of destroy of the structure from global responseand local response.The main conclusions are achieved as follows:①From the global response of SSFDHs during rare and devastating earthquake,upper to middle layers are the locations with larger deformation and the plastic hingesare mainly concentrated in upper layers as well as upper floors, which should be paidattention while designing.②The failure mode of each model can be generalized as “beam-column mixedhinges” which shows the number of hinges in beams are larger than columns; Thelevels of damage of beam hinges are more serious than column hinges, the first hingesappear at the bottom of columns and would yield during inputting of most waves; Beamhinges are mainly located at the upper floors. Beam and column hinges would developsufficiently during earthquake, which would increase more remarkably than the action of rare earthquake, especially the ductility demand of columns at the upper layer. As aresult, it is a need to enhance the ductility constructional details of columns at the upperlayers.③With the increase of number of off-layer floors, the more beam hinges wouldappear at the lower floors of off-layers. If the off-layers just be a small proportion of thestructure that the weak regions of SSFDH would be upper columns, upper layers andupper floors; Else if the off-layers be a large proportion of the structure that the locationof being first destroyed and serious damaged would be upper columns, upper layers andtheir neighbor floors while the lower floors of off-layers would follow the destruction.④With the increase of spans of off-layer, the more the structure would be "close to"common non-off-layer structure, but the upper layer would still be the floor with largestinter-story drift ratio and the location with primary hinges would be upper columns.Furthermore, the existence of off-layer makes upper columns and their neighbor floorsbecome the first location of being destroyed during earthquake, and the upper floors aswell as the basic region follow the destruction, what’s more, the level of damage ofupper floors would be more serious than floors at off-layers. |
PDF Full Text Request