Authors:Cristian Vulcu, Aurel Stratan, Adrian Ciutină, and Dan Dubină
: production process, mechanical and chemical properties, fabrication properties, in Use and application of high performance steels for steelstructures , Ed. by Günther, H. P., Structural Engineering Documents, SED 8, IABSE, Zurich, 2005
Authors:Dimitrios Kaziolas, Khairedin Abdalla, and Charalambos Baniotopoulos
., Joó A. Design resistance of bracing details, Budapest University of Technology and Economics, Research Report , 2002.
Eliášová M., Hoblíková M., Peleška K., Sokol Z., Vraný T. and Wald F. Steelstructures 10, Worked examples
Moment resisting frames are considered as an effective seismic force resisting system that is used for steel structures. Some of these structures that were built in high seismic hazard zones were designed according to old strength-based design codes. Currently, these structures do not meet the requirements of the new seismic codes. Therefore, the seismic retrofit of these structures is mandatory and cannot be overlooked. Steel braces and concrete-steel composite elements are common solutions for enhancing the seismic behavior of existing steel frame structures. This paper presents a numerical study that evaluates different possible techniques for the seismic retrofit of existing steel moment-resisting frame structures. The study investigates the performance of three multi-story buildings with different heights that are located in a high seismic hazard zone. Three retrofit techniques were introduced including; 1) X-Steel braces, 2) buckling restrained composite braces, and 3) composite concrete-steel plate shear walls. The seismic performance enhancement of the studied structures was evaluated in terms of the structure’s fundamental period, maximum inter-story drift and maximum base shear-to-weight ratios. Moreover, the cost of retrofitting material was estimated for each technique and they were compared to select the retrofit technique with the least constitutive material cost.
Before the 1960s the ductility notion was used only for characterizing the material behaviour. After Baker's research on plastic design, this concept has been extended to the structural level. This paper provides a general overview of ductility. The paper examines the behaviour of material ductility, cross-section ductility and member ductility separately, then it studies how the sum of the effects of all these ductilities affect the structural ductility. The effect of the different ductilities can be built into the structural behaviour through an interactive hinge model. The model of the interactive hinge also takes into consideration the effects of the residual stresses and deformations, the strain hardening and the plate buckling.