Static And Dynamic Analysis Of Three Span Continuous Skew T Beam Bridge With Small And Medium-Span

In the past more than 10 years,with the driving of economic development in our country,the transportation industry has made great progress.In order to adapt to the characteristics of linear smoothness,fast driving and heavy traffic flow,the continuous skew girder bridges emerged as the times require in the construction of high grade highway,which not only avoid the waste of materials like orthogonal,but also have stronger ability to overcome obstacles,and in the construction of highway bridge have received widely favored.However,there are many differences between the skew bridges and the orthogonal bridges in the structure and the way of bearing.Moreover,in many key issues,the present related studies are not very thorough,such as the influence of skew angle on the internal forces,lateral forces and transverse distribution of the continuous skew T beam bridges with small and medium span;the influences of skew angle and width span ratio on the vibration modes and natural frequencies of continous skew T beam bridges have not been clearly defined.Based on the three span continuous skew T beam bridge,the static and dynamic characteristics of three span continuous skew T beam bridges with different skew angles are studied by the combination of the real bridge load test and the finite element numerical analysis.The main research contents are as follows:(1)According to the grillage theory,the finite element models of the three span continuous skew T beam bridges with different skew angles are established by using the finite element software MIDAS CIVIL.Combined with the static load test of the actual bridge,the correctness of the established finite element models are verified,and the preparation for the next research is made.(2)In the study of static characteristics,taking the skew angle as the influence parameter,this paper studied the change laws of the midspan positive moments,the fulcrum negative moments,the support reaction forces,the midspan deflections and the load transverse distribution coefficients under different load conditions.(3)In the aspect of dynamic characteristics,the modal analyses of the three span continuous skew T beam bridge finite element models under different skew angles are carried out,and the change laws of the vibration modes and natural frequencies of the structures under different skew angles are obtained.According to the calculation results of the finite element models,the formulas of < General code for design of highway bridges and culverts> for calculating the fundamental frequencies of the bridge are modified so that they can be applied to the fundamental frequency calculation of this kind of skew bridges,and the modified formulas are verified by real bridge test data.(4)The results show that the different connection modes of the main beams(rigid connection and articulation)have very little influence on the dynamic characteristics of the structure,and can be neglected;The errors between the vertical bending natural frequencies of structures with different width span ratios are less than 5%,which shows that the influences of width span ratios on the vertical bending natural frequencies are very small.But with the increase of the width span ratio,the number of the flexural torsional coupled modes will increase in the natural vibration modes of the structure.