Analysis Of Global Ductility Of Staggered Truss Steel Frame In Severe Earthquake

Staggered Truss Steel Framing system has seen a worldwide renaissance because it can yield great economy and maximum architectural and planning flexibility. To generalize the use of the system, more works need to be done on design methodology, details of seismic design and seismic design methodology.As part of national natural Scientific Research Fund (Grant No. 50078021), the dissertation is emphasized on investigating the failure modes and evaluating the global ductility of the Staggered Truss Steel Frame under the action of high-seismic excitation. The main conclusions are outlined as the following:1) Using nonlinear static procedure and nonlinear dynamic procedure to investigate the. failure modes of two Staggered Truss Steel Framing buildings, the results indicate the plastic hinges mainly formed in truss members, especially concentrated to the vierendeel panel. It means the vierendeel panel in the center of the truss can provide significant ductility in the structural response and the failure mode is suitable for our performance services.2) Using analysis results of the displacements given by times history analysis and hysteretic loops of the four structural systems including Staggered Truss Steel Framing system(STSF), Ordinary Steel Moment- resisting Frame system(OSMF), Concentric Braced Frame(CBF) and Steel Frame System with Concrete Shear Walls(SFCW), the Global ductility of the Staggered Truss Steel Framing system under the action of high-seismic excitation is compared with the others. It shows that the Global ductility of the Staggered Truss Steel Frame with non-diagonal braces truss is as large as 6, and the Global ductility of the Staggered Truss Steel Frame with diagonal braces truss is as large as 4.3) After investigating the influence of several types of truss on the global ductility of the Staggered Truss Steel Framing system, a type of truss which is called SCF truss is proposed. The truss actmostly as Eccentric Braced Frames(EBC). The analysis show the SCF truss can help improve the Global ductility of the Staggered Truss Steel Frame with diagonal braces truss.4) The different between global ductility gained using fully restrained model for truss connections and partial restrained model for truss connections indicate the fully restrained is better for the global ductility of the Staggered Truss steel framing.5) The arrangement of Non-Truss on the First Floor (NTFF) is pleasure for architectural flexibility, but its bad for seismic design. After investigating the influence of NTFF on the global ductility of the Staggered Truss steel framing, it show that NTFF lead to decline of stiffness and lead to a bad failure mode which plastic hinges always formed in base of columns. So it's suggested that NTFF should be avoided in the region of seismic fortification intensity is 8.6) The investigation indicate the ratio of building height and building width is interrelated with the global ductility of the Staggered Truss steel frame, the large the ratio, the small the global ductility. So its suggested that the ratio of building height and building width for the Staggered Truss steel framing is better less than 5 in the region of seismic fortification intensity is 7 and less than 4 in the region of seismic fortification intensity is 8.