Dynamic Performance Study Of Steel Frames Based On Component-based Joint Models Under Progressive Collapse

Many forgein building structural design codes regard progressive collapse assevere threat, and specify the flow path of assessment and design methods to prevent it.The study of progressive collapse in China started later than abroad so there isdeficiency corresponding specification sections, which involves vague rules only butwithout specific checking calculation steps. Foreign regulations such as the generalservices department (GSA) and the department of defense (DoD) in USA adopt linearstatic method with a coefficient of2.0for static loads to consider the dynamic effectcaused by accidental loading. In addition, DoD also recommends that static loadsshould multiply the dynamic increased factor (DIF) for nonlinear static design, and theDIFs here decrease with the increase of allowing deformation rather than a constant of2.0in linear elastic static analysis. There are increasing rsearch works, which havefound that the difference between linear elastic static approach and nonlinear dynamicanalysis is obvious and can not be negligible. However, the idea of DoD, i.e. nonlinearstatic design with DIF, is rather valuable, although some defects exist in the DoD interms of the specifications on DIF. In view of this, this thsis will take Alternate PathMethod to study dynamic performance of two dimentional (2D) steel frames based oncomponent-based models under sudden column removal scenarios.The comparison between the dynamic response of component-based modelsimulated by finite element software and experimental tests results shows that thecomponent-based method is reliable. And that, the dynamic response of two-span2Dsteel frames subjected to sudden gravity loading is simulated by finite elementsoftware with component-based model. These two-span2D steel frames employ twotypes of beam-column connetions, including web cleat connetion and top and seat withweb angle connection. The DIFs can be obtained by comparing the acquired dynamicresponse against the corresponding nonlinear static response of the steel frames. Lastly,DIFs calculated by this paper, are compared with regulations of DoD and a simplifiedmethod proposed by Izzuddin. As a result, it is found that the reasults of this thesis arein good agreement with Izzuddin’s simplified method. It is also found that DIFregulations of DoD is unsafe can be made. Therefore, Izzuddin’s simplified method isrecommended for resisting progressive collapse design since finite element analysis isnot convenient to practical usage. At the end of this thesis, summaries of dynamic response of progressive collapseare made and some suggestions about further study are also stated.