The Research On Experiment And Nonlinear Design Methods Of Specially Shaped Steel Frame Structures

With the rapid development of modern architectural design concept, manyspecially shaped buildings with complex building model and volatile vertical shapeemerge. Because of the great advantages and increasingly mature design method ofsteel structure, it has a large number of applications in this kind of specially shapedbuildings. Compared to the conventional structure, specially shaped steel structureshave a relatively complex design method considering many more factors which mostlyrequire complex nonlinear analysis. It is hard to predict the behavior and real carryingcapacity of specially shaped structures based on past experience; What is more, thereis only a little information of correlated design method and no code to refer to. Toensure that the structure is both safety and economic, it is of important practicalsignificance to establish a reasonable and reliable theoretical calculation model andaccurate calculation analysis procedure to guide this kind of specially shapedstructure design. Therefore, necessary experiment and design approach analysis ofsuch building structure are carried out.On the background of a large specially shaped steel frame with fold-linearinclined column, the dissertation focused on the following several aspects.(1) Large-scale test is performed on the existing specially shaped steel framestructure with large no uniform cantilever beam and fold-linear inclined column inorder to provide experimental results for ultimate static strength and designverification. The corresponding finite element analysis emphasis on structure bearingperformance and the weak part, and providing theoretical guidance for the rationaloptimization of structural design.(2) On the basis of the above research, further scaled model test and finiteelement analysis on the fold-linear inclined column in the specially shaped steel framestructure is developed to provide experimental results for ultimate compressivecapacity and design verification. Combined with test results and the finite elementcalculation results, the deformation features and internal force distribution rule offold-linear inclined column are analyzed. The failure mode and location, the load-thedisplacement curve and the ultimate bearing capacity of fold-linear inclined columnare also included in the research to verify the correctness of theoretical analysis anddesign of the prototype structure. (3) Based on the nonlinear finite deformation theory, this dissertation set up yieldsurface plastic hinge model for the nonlinear analysis of the specially shaped steelframe and composes the corresponding computer program for the whole processnonlinear analysis of the specially shaped steel frame on the basis of the overallultimate bearing capacity. Finite element analysis and experimental results werecompared to verify the accuracy of the nonlinear analysis theory.(4) In the structure analysis of the specially shaped steel frames, special-shapedcolumns are classified as an equivalent inclined column. Based on the principle ofequivalent stiffness, the equivalent substitution method is proposed. The equivalentsubstitution model is established in which the fold-linear column is equivalent to thestraight line column. Through the equivalent stiffness in order to achieve equivalentnonlinear internal force, the basic principle and idea is put forward.(5) The inclined column force analytic model of the specially shaped frame isestablished, which analyses the initial inclination, lateral restraint of the rod end,rotational spring constraints of both ends of the column, loads, stiffness of thecolumn itself and other parameters on the nonlinear influence of the inclined column.(6) An analytical model on the fold-linear inclined column in the speciallyshaped frame is established. According to the method of straight-line columnequivalency, moment magnification factor formula on symmetry fold-linear inclinedcolumn is carried out. By the introduction of non-symmetric factors andrelated parameters, the applicability of former formula will expand to non-symmetricfold-linear inclined column. Put forward the general expression of the fold-linearinclined column moment amplification factor.(7) Combine the above research results, nonlinear simplified design approach ofthe steel frame with fold-linear inclined column are founded which is compared tononlinear precise analytical method to verify the accuracy and practicality of thesimplified design approach.