Formation of plastic rotational hinges in steel frames for monotonic and cyclic loading

The formation of concentrated rotation in a steel Special Moment-resisting Frame was explored. Original analytical and experimental models were combined with available literary research to show that the traditional assumption of developing a plastic hinge by yielding of the steel is extremely unlikely.; Frame models were analyzed to obtain the global behavior of building frames. An in-depth study of actual hinge formation used fiber-element model for the cross-section and length of the hinge region. Pushover and time-history analytical studies were conducted to determine various parameters of inelastic plastic hinges.; Parameters of hinge behavior include: moment strength, shear strength, moment-gradient, length, rotation, strain ductility and rotation ductility. The relationship between strain ductility demand and rotation ductility was considered. A correlation between cumulative excursion plastic strain and cycles of inelastic behavior was found. Important input parameters were found to be the length of the bay and the post-yield stiffness of the material.; A review of various experimental studies showed that the traditional methods of steel construction have two methods of developing large rotations: fracture of the tension flange or local buckling of the compression flange. Formation of rotation by yielding of the steel has been seen in few experiments. Fracture has been the dominant failure mode in both experimental studies and documented building performance during earthquakes.; A new connection detail was developed that could be easily implemented into the column-tree method of construction. This detail was studied with an experimental program and analytical model to estimate the expected seismic performance. Bolted-flange splice plates with reduced yield zone cross-section were tested. The combination of slippage of the bolted joint and uniaxial yielding of the reduced area region of the splice plates allowed significant deformation along the flange.; The steel shear stud between the steel beam and concrete slab was also tested to determine the slab contribution to the behavior of the steel beam. The plates and/or angle assemblies were tested which connect the web of the beam.