Comparative Study Of Steel-Concrete Hybrid Girder Rigid Frame Bridge And Continuous Rigid Frame Bridge

With the increase in the number of prestressed concrete continuous rigid frame bridges,there are two major diseases: box cracking and mid-span deflection,which seriously affect their service life and limit This type of bridge continues to develop to a larger span.Steel-mixed composite beam continuous rigid frame bridge can give full play to the advantages of the two materials,better meet the structural force and function requirements,greatly improve the applicable span of the beam bridge,in the context of China’s transportation strategy construction and future bridge application,It has very broad development prospects in the field.Based on the Yulinhe Bridge(110m+210m+110m continuous rigid frame bridge),to carry out comparative analysis and comprehensive evaluation of the two bridges.The main research contents include the following aspects :(1)Establish simplified mechanical models of ordinary continuous rigid frame bridge and steel-concrete hybrid girder rigid frame bridge.Analyze expressions of internal forces of key sections through structural mechanics principles and advanced mathematical knowledge.(2)On the basis of keeping the total length of the original bridge unchanged,reduce the side-to-span ratio,and replace the 85 m concrete box girder in the main span with a steel box girder.Use a combination of internal and external distribution to trial design a steel-concrete hybrid girder rigid frame bridge,propose three trial design schemes,carry out finite element modeling,stress calculation and analysis of each scheme,and finally determine the scheme of using external prestress in the mid-span.(3)Comparative analysis of static,stability and economy of ordinary continuous rigid frame bridge and steel-concrete hybrid girder rigid frame bridge;for the two main diseases of ordinary PC continuous rigid frame bridge cracking and span deflection,from the main tensile stress,Comparative analysis of the disease control of the two bridges in the four aspects of prestress loss,box beam stiffness reduction,shrinkage and creep;and analysis of the difference in the construction of the two bridges.(4)Compare the natural frequency and mode shapes of the two bridges.The dynamic time history analysis of the two bridges under the action of triangular moving load is carried out,and the dynamic response of the mid-span displacement and mid-span acceleration of the main bridges of the two bridges is calculated,analyzed and compared with different driving speeds,and the running comfort of the two bridges is simply compared Evaluation.(5)Determine the structural performance indicators,technical and economic indicators,and social benefit indicators of the two bridges,use the analytic hierarchy process to determine the weights of the indicators,use the gray correlation coefficient method to normalize the indicators of the two bridges,then establish the gray correlation matrix,and finally use the Topsis method The relative closeness of the common continuous rigid frame bridge scheme and the mixed beam continuous rigid frame bridge scheme are 0.4117 and 0.5883 respectively,It shows that the mixed beam continuous rigid frame bridge is the better plan under the comprehensive consideration of the three major indicators,and it has good application and development prospects in the choice of the beam bridge bridge with a span of more than 200 meters in the future.