h.h heydari - Islamic Azad University, Varamin branch, Civil engineering department Shahidan Ave., Azadi Ave., Tehran, Iran, ۱۳۴۳۹-۹۷۹۶۴
f ranjbaran - Islamic Azad University, Islamshahr branch, Civil engineering department Namaz Sq., Sayad Shirazi Ave., Islamshahr, Tehran, Iran, ۳۳۱۴۷-۶۷۶۵۳

Moment resistant column-beam connections have been widely used in design and construction of steel structures around the world. These connections suffered fracture failures during Northridge and Kobe earthquakes. Researches indicate that the most effective factor of this failure was welding defect also available material toughness is less than fracture toughness demand. In this paper fracture is evaluated in terms of stress intensity factor (K) in linear elastic analysis, crack tip opening displacement (CTOD) and energy release rate (J contour integral) in nonlinear analysis. The 2D-Finite element model of standard connection is developed by Abaqus (6.14-2) with fracture mechanics procedure. For evaluating fracture behavior, it is defined an initial crack at the interface of groove weld of the bottom beam flange and column flange with different length. The type of loading is monotonic and cyclic loading which applied as displacement at the end of the beam. The results show that K increases with the increase of applied crack length. Inelastic analysis for evaluation moment-rotation curve of connection is performed

moment connection, steel structure, fracture