The Static And Dynamic Performance Study Of Long-span Self-anchored Suspension Bridges And Parameter Sensitivity Analysis

Whether on the mechanics property or on the construction aspect, theself-anchored suspension bridge differs a lot from conventionalsuspension bridge. This dissertation, through the experience ofengineering practice, probes into the self-anchored suspension bridgefrom several respects such as the static and dynamic mechanicalproperties, parameter sensibility analysis as well as anchor structure, etc.The main research work covers the following aspects:(1) Based on the deflection theory and virtual displacement principleand considering Beam-Column effect. The dissertation deduced a set ofpractical calculation formulas about the internal force and deforming ofstiffening girder by means of trigonometric series. Then, several realself-anchored suspension bridges were analyzed by means of this method.The results agree well with that of finite displacement theory. It indicatesthat the deflection theory is adoptable to study and analyze the influenceof parameter on the internal force and deforming. This method, especiallyin the preliminary design stage, is much more available on the selectionof structure and devising of parameter in comparison with FEM(2) The method based on the virtual displacement principle can beapplied to study the influence of some parameters such as the span,sag-span ratio of the cable, stiffness of the girder on the structural staticproperty. The results reveal that for self-anchored suspension bridges, arather large sag-span ratio is adopted for the reason that with increasingsag-span ratio and enhancement on the vertical flexural rigidity of thestructure, the pressure of stiffening girder is reduced and influence onworst-case moment is comparatively small. It is a favorable case toenhance structural stiffness and reduce structural inner force by properlyreducing the length of side span. However, undersize side span will addthe vertical component force in the anchorage zone and structuralkentledge. The flexural rigidity of stiffening girder is an important factorof general structural rigidity. Proper side span and extension length playan effective role to reduce vertical structural deflection and kentledge inthe anchorage.(3) By analyzing the mode after the modification of structural para- meter, parameter, the method mentioned above is put forward by combin-ing finite-element method with matrix perturbation theory. The methodavoided solving generalized eigenvalue problem frequently when designparameter varies in small magnitudes. By analyzing the parametersensibility of a self-anchored suspension, it shows that it is easy to obtainvibration modal after the structural modification and sensibility ofstructural designing parameters. The accuracy and economical efficiencyare satisfying.(4) Based on the aeroelastic analysis of bridges multimode approach,sensitivity analysis method has been established. By applying theeigenvalue theories, this method analyzes the effect on the aerodynamicproperty in the structure of a self-anchored suspension bridge through theconsideration of the feature of flutter and buffet, and analysis of sectionalconfiguration, modal couple, flutter derivatives and constructionprocedure from the results of wind-tunnel test. From the analysis ofaerodynamic property parameters on two real suspension bridges, it canbe discovered that for self-anchored suspension bridges with flatstreamlined steel box girder, the results of the flutter critical windvelocity are close to that of the thin flat plate and major energy focuses onthe first torsion model, which means that torsion modal is the key factor.The increasing of structural damp will suppress buffet response in a givenrange and the lateral swing of stiffening girder will influence the verticalresponse. All these characteristics show that aerodynamic property ofself-anchored suspension bridges approaches that of cable-stayed bridges.(5) Comprehensive analysis are carried on in a new entire-weldingsteel anchorage system by studying the characteristics of the mechanicsproperty in an ideal situation and the elastic flexion loads on an initialdefect condition. The results indicate that the distribution of stress anddeformation in anchorage segmental are extremely complicated under thefunction of designing axial force and welding-induced residual stressesare large in web plate and anchorage zone. Adequate attention should bepaid in the designing and manufacturing procedure of anchorage box.