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Capacity Design Optimization of Steel Building Frameworks Using Nonlinear Time-History Analysis Date 2012-08-24 Author Xue, Yusong A thesis presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Doctor of Philosophy in Civil Engineering Abstract This study proposes a seismic design optimization method for steel building frameworks following the capacity design principle. Currently, when a structural design employs an elastic analysis to evaluate structural demands, the analysis results can be used only for the design of fuse members, and the inelastic demands on non-fuse members have to be obtained by hand calculations. Also, the elastic-analysis-based design method is unable to warrant a fully valid seismic design since the evaluation tool cannot always capture the true inelastic behaviour of a structure. The proposed method is to overcome these shortcomings by adopting the most sophisticated nonlinear dynamic procedure, i.e., Nonlinear Time- (or Response-) History Analysis as the evaluation tool for seismic demands. The proposed optimal design formulation includes three objectives: the minimum weight or cost of the seismic force resisting system, the minimum seismic input energy or potential earthquake damage and the maximum hysteretic energy ratio of fuse members. The explicit design constraints include the plastic rotation limits on individual frame members and the inter-story drift limits on the overall performance of the structure. Strength designs of each member are treated as implicit constraints through considering both geometric and material nonlinearities of the structure in the nonlinear dynamic analysis procedure. A multi-objective Genetic Algorithm is employed to search for the Pareto-optimal solutions. The study provides design examples for moment resisting frames and eccentrically braced frames. In the examples some numerical strategies, such as integrating load and resistance factors in analysis, grouping design variables of a link and the beams outside the link, rounding-off the objective function values, are introduced. The design examples confirm that the proposed optimization formulation is able to conduct automated capacity design of steel frames. In particular, the third objective, to maximize the hysteretic energy ratio of fuse members, drives the optimization algorithm to search for design solutions with favorable plastic mechanisms, which is the essence of the capacity design principle. For the proposed inelastic-analysis-based design method, the seismic performance factors (i.e., ductility- and overstrength-related force reduction factors) are no longer needed. Furthermore, problem-dependent capacity design requirements, such as strong-column-weak-beam for moment resisting frames, are not included in the design formulation. Thus, the proposed design method is general and applicable to various types of building frames. URI [Hidden Content] Collections Theses & Dissertations Civil and Environmental Engineering Theses & Dissertations دانلود: [Hidden Content] Capacity_Design_Optimization_of.pdf

Seismic Performance of Steel Plate Shear Walls Using Nonlinear Static AnalysisDHAR, MOON MOON (2015) Seismic Performance of Steel Plate Shear Walls Using Nonlinear Static Analysis. Masters thesis, Concordia University. AbstractUnstiffened steel plate shear wall (SPSW) is considered as a primary lateral load resisting system due to its significant post-buckling strength, high ductility, stable hysteretic behaviors and robust initial stiffness. Nonlinear seismic analysis can accurately estimate structural responses, however, the method is very time consuming and may not be suitable for regular engineering practice. On the other hand, traditional pushover analysis method does not consider contributions of higher modes to the structural responses and thus, often do not provide good estimation of seismic responses for taller buildings. Capacity-Spectrum Method (CSM) and modal pushover analysis (MPA) are two simple nonlinear static methods that have been proposed and recently used for seismic performance evaluation of few lateral load-resisting systems. This research further examines the applicability of CSM and MPA methods to assess seismic performance of steel plate shear walls. A nonlinear finite element model was developed and validated with experimental studies. Three different SPSWs (4-, 8-, and 15-storey) designed according to capacity design approach were analysed by subjecting the steel shear walls under artificial and real ground motions for Vancouver. The CSM and MPA procedures were applied to analyse the selected SPSWs and the results were compared with more accurate nonlinear seismic analysis results. It is observed that both CSM and MPA procedures can reasonably predict the peak roof displacements for low-rise SPSW buildings. In addition, MPA procedure, which includes contributions of higher modes when estimating seismic demands of buildings, provides better predictions of critical seismic response parameters for taller SPSWs. منبع: [Hidden Content] دانلود: [Hidden Content]1/Dhar_MASc_S2015.pdf Dhar_MASc_S2015.pdf

Displacement based design of reinforced concrete structural walls: an experimental investigation of walls with rectangular and t-shaped cross-sections Thesis (Ph. D.)--Clarkson University, 1995. Includes bibliographical references (p. 134-141) and abstract. Thomsen__Wallace-Disp-based_design_of_RC_structural_walls_An_experimental_investigation_of_walls_with_rectangular_and_T-shaped_cross-sections_NSF_report-1995.rar