Box-Girder Design Parameter Optimization Of Long Span Rigid Frame Bridge

The long span PC continuous rigid bridge is good characteristic of structure stress performance,maintain,construction,driving and adaptability,so this bridge is widely applied in our country.After extensive investigation and research,both at home and abroad for such bridge design parameter optimization analysis is rare.Continuous rigid frame bridge with complex design parameters of the bridge system is widely used,but more controversial.First,this bridge's recommend-edge in the cross-ratio was 0.54 to 0.56,while pier supports to ensure that there is sufficient to maintain the pressure should not be a negative force in the actual project.But many examples of the bridge are far from the ratio in this investigation.In this paper,some of the existing bridge statistical analysis such that the distribution of its value between 0.52 to 0.64.Assuming five different edges,in the cross-over composition of its edge in the cross-ratio is as follows:0.518,0.536,0.559, 0.586,and 0.614.the author set up structural modeling and analyze later results for 220m main span of the three-span continuous PC rigid frame bridge.Secondly,before the use of the new bridge norms,such high-root box girder bridges ratio ranged from 0.050 to 0.0556 in general,and by the same method in the statistics,China's existing some bridges' value in the general admission is between 0.05～0.06.Therefore, with main span of 220 m unchanged,the roots were selected with a high degree of 11.5 m, 12.0m and 12.4m,12.8m and 13.0m for model building.At the same time,the span and the cross height ratio is between 50-60(that inter-high cross-ratio is 0.167～0.02).According to the data statistics,when main span is bigger than 200m,H/L in generally takes in 0.015～0.020;when the span is smaller than 200m,H/L is bigger than 0.02 in generally.Therefore cross heights were selected from 3.2m,3.6m,4.0m, 4.5m to 5.0m which H/L distinguished 0.0145,0.0164,0.0182,0.0205 and 0.0227.Furthermore,the main beam generally use variable cross-section box girder,box girder used at the lower edge of the parabola 1.5～2.0;greater than 200 m main span box girder of the bridge curve often margin of 1.5～1.8;This paper selects six Group data, namely:1.5,1.6,1.7,1.8,1.9 and 2.0.By using MIDAS/CIVIL for modeling and structural analysis,we would like to obtain the conclusion that the structure of the corresponding curve of load distribution.After comparative analysis,this paper will give us the variable optimization advices about box girder design parameters above.On the basis of data collection and analysis,the paper draws lessons from the built bridge and the newest research achievement.Meantime,A bridge in Yunnan province was taken as an example to research of the box-girder parameter analysis of the long span continuous rigid frame bridge.According to several different parameters' analysis by professional software,the author could obtain some valuable conclusions.