Advanced analysis for frame design
Recent research efforts have focused extensively on the development of advanced analysis techniques and their possible application in limit-states design of rigid and semi-rigid steel frames. Both the European and Australian limit states design codes allow use of advanced analysis for design of frames in which the members are made of compact sections and are sufficiently braced against lateral-torsional buckling. "Advanced analysis" is intended to indicate any method of analysis that sufficiently captures the strength limit states encompassed by specification equations for member proportioning such that the checking of such equations is not required. This thesis is dedicated to the development and application of such methods for the limit-states design of rigid and semi-rigid steel frames.^ The first part of the thesis provides an overview of the current impetus behind research in inelastic analysis and design. This is followed by a concise encapsulation and some suggestions for improvement of current elastic analysis/design approaches for frame design. Efforts are devoted to investigating possible methods for accurate modeling the inelastic behavior of frame members. The adequacy of second-order elastic-plastic hinge analysis for use as advanced analysis is investigated through a series of benchmark checks. Some limitations of the plastic hinge method for representing number stiffness and strength are identified, which lead to the development of two alternative analysis approaches termed the notional load plastic hinge and refined plastic hinge approaches. The accuracy of these approaches for representing system and member strength and stability is confirmed by comparing the predicted force distributions, load-deformation responses and ultimate strength results with the more "exact" plastic-zone solutions. The studies conclude that these inelastic analysis approaches have general validity and may be applied for the design of a wide range of frame structures. The proposed inelastic models are accurate also at an individual member level; therefore, member capacity checks can be waived in using these analyses model for planar frame design.^ The final part of the thesis provides practical methods of incorporating connection flexibility, joint size, panel-zone deformation, and member imperfection effects for assessment of system strength and stability. Examples are provided to illustrate the procedures of using advanced inelastic analysis in conjunction with limit-states design provisions for proportioning steel frame members and joints. ^
Major Professor: Wai-Fah Chen, Purdue University.