The most important parameter used to determine force reduction factors in force-based design procedures adopted in the current seismic codes is the structural ductility. For a structure supported on a flexible foundat...The most important parameter used to determine force reduction factors in force-based design procedures adopted in the current seismic codes is the structural ductility. For a structure supported on a flexible foundation, the ductility factor could be affected by foundation compliances. The ductility factors given in the current codes are mostly assigned ignoring the effect of SSI and therefore the objective of this research is to assess the significance of SSI phenomenon on ductility factors of stack-like structures. The deformed configuration of stack-fike structures is idealized as an assemblage of beam elements considering nonlinear moment-curvature relations, while a linear sway-rocking model was implemented to model the supporting soil. Using a set of artificial records, repeated linear and nonlinear analyses were performed by gradually increasing the intensity of acceleration to a level where the first yielding of steel in linear and nonlinear analyses is observed and a level corresponding to the stack collapse in the nonlinear analysis. The difference between inelastic and elastic resistance in terms of displacement ductility factors has been quantified. The results indicate that foundation flexibility can decrease the ductility of the system and neglecting this phenomenon may lead to erroneous conclusions in the prediction of the seismic performance of flexibly-supported R/C stack-like structures.展开更多
An effective rapid assessment technique, called ＂P25 Scoring Method＂, has been developed and tested on 26 different case studies recently, in order to predict the collapse vulnerability of the R/C buildings. After a...An effective rapid assessment technique, called ＂P25 Scoring Method＂, has been developed and tested on 26 different case studies recently, in order to predict the collapse vulnerability of the R/C buildings. After a short description of the approach, the study presents the sensitivity study of the method to the selected structural parameters by considering incremental deviation of the final scores from the base model. Further, the methodology was applied to an additional 100 damaged buildings in order to check the reliability of the method and some necessary modifications have been applied to the algorithm after considering this larger database. The evaluation of the results has been interpreted as a beneficial guidance for local authorities. The risk bands are defined according to the final scores and the effect of changing the band-width has also been studied through a safe but an economical procedure. A satisfactory correlation of the method with real damage states is obtained and a ready-to-use methodology has been introduced for future studies.展开更多
文摘The most important parameter used to determine force reduction factors in force-based design procedures adopted in the current seismic codes is the structural ductility. For a structure supported on a flexible foundation, the ductility factor could be affected by foundation compliances. The ductility factors given in the current codes are mostly assigned ignoring the effect of SSI and therefore the objective of this research is to assess the significance of SSI phenomenon on ductility factors of stack-like structures. The deformed configuration of stack-fike structures is idealized as an assemblage of beam elements considering nonlinear moment-curvature relations, while a linear sway-rocking model was implemented to model the supporting soil. Using a set of artificial records, repeated linear and nonlinear analyses were performed by gradually increasing the intensity of acceleration to a level where the first yielding of steel in linear and nonlinear analyses is observed and a level corresponding to the stack collapse in the nonlinear analysis. The difference between inelastic and elastic resistance in terms of displacement ductility factors has been quantified. The results indicate that foundation flexibility can decrease the ductility of the system and neglecting this phenomenon may lead to erroneous conclusions in the prediction of the seismic performance of flexibly-supported R/C stack-like structures.
文摘An effective rapid assessment technique, called ＂P25 Scoring Method＂, has been developed and tested on 26 different case studies recently, in order to predict the collapse vulnerability of the R/C buildings. After a short description of the approach, the study presents the sensitivity study of the method to the selected structural parameters by considering incremental deviation of the final scores from the base model. Further, the methodology was applied to an additional 100 damaged buildings in order to check the reliability of the method and some necessary modifications have been applied to the algorithm after considering this larger database. The evaluation of the results has been interpreted as a beneficial guidance for local authorities. The risk bands are defined according to the final scores and the effect of changing the band-width has also been studied through a safe but an economical procedure. A satisfactory correlation of the method with real damage states is obtained and a ready-to-use methodology has been introduced for future studies.
