Optimization And Study On Free-vibration Characteristics Of Internal And External Type Steel Box Tied Arch Bridge

The Internal and External Type Steel Box Tied Basket-Handle Arch Bridge is anew bridge type which the traditional single arch is taken place by internal and externalarchs.The new bridge type’s advantages are aesthetically pleasing and novel structureand efficient construction. The dynamic characteristics of Internal and External TypeSteel Box Tied Basket-Handle Arch Bridge researched in this paper. The main contentsof this paper include:Organizing and summarizing related theories about vibration analysis of arch.Expounds the approach of the analytical method and the finite element method, which isthe theoretical base of the subsequent analysis. With the principle of the minimumpotential energy, the approximate formula for in-plane basic frequency of the pure archstructure has been deduced. Verified the accuracy of the formula through MATLAB andANSYS numerical examples. The formula reveals the rule of the arch structurevibration.A three-dimensional finite element model of Yanghu Bridge is developed to makemodal analysis. Then the dynamic testing with ambient vibration is carried on thisbridge. For getting the accurate dynamic properties of the structure, test scheme iscarefully designed. The testing provides vibration data for the identification of themodal parameters.The testing gets the first six stepped natural frequency, mode and damp ratiosthrough several time-domain and frequency-domain methods. The test method wasproved to be correct by well agreement between the results of test and calculate. Thefinite element model that reflects the built-up structural dynamic properties can beserved as a baseline model in the succeeding dynamic response analysis undercomplicated excitations, long-term health monitoring and structural conditionassessment of Yanghu Bridge.The effects of parameters such as rise-span ratio of arch rib, leaning angle,arrangement of wind bracing and arch stiffness on free-vibration characteristics of theInternal and External Type arch bridge was studied which is on the premise of reliabilitycalculation model. Blindness in the choice of optimization variables is avoided by theanalysis of sensitivity.Using the zero-order optimization method to design the dynamic performance ofthe model which based on ANSYS Parametric Design Language. With the optimizeddesign parameters which satisfied the constraint condition, the in-plane basic frequency of Internal and External Type bridge will be maximum. The dynamic performance ofthis kind bridge will be improved.