الفهرس 
CHAPTER 1 INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The concrete-filled steel tube (CFST) column system has many advantages compared with ordinary steel or reinforced concrete systems. One of the main advantages is the interaction between the steel tube and concrete: local buckling of the steel tube is delayed by the restraint of the concrete, and the strength of concrete is increased by the confining effect of the steel tube. The orientation of the steel and concrete in the cross section optimizes the strength and stiffness of the section. The seismic design of steel or composite buildings is based on the concept of dissipative structures, where specific zones of the structures should be able to develop plastic deformation, mainly in ductile members, to dissipate the seismic energy. Under seismic action, the non-dissipative zones should behave elastically to avoid the sudden collapse of the building. This study considers the basis of the ”Dual-Steel Concept”, where High Strength Steel (HSS) is used for non-dissipative members and Mild Carbon Steel (MCS) for dissipative members. On the other hand, the study shows the development of the through-type concrete-filled square steel tube column-to-beam connection. Subsequently, six types of concrete-filled steel tube squares column-to-beam connections (without stiffeners, with different shapes and thicknesses of the stiffener cross-section diaphragm and with the beam continuing through the CFST column) were fabricated in half and tested according to the ANSI/AISC SSPEC 2002 cyclic loading program. An analytical study was conducted to study some variables not covered by the laboratory study program. Finally, design guidelines and recommendations for the use of stiffeners in resisting failure were developed.