Study On Key Issues Of Long-span Suspension Bridges With Steel Truss Girder

Steel truss girder and steel box girder are usually used in modern suspension bridges,while study on suspension bridges with steel truss girder is on fewer in China. Suspension bridge with steel truss girder is powerful ompetitive in the field, with the advantage of unique adaptive capacity to double traffic and mountain construction of suspension bridge. Studies on suspension bridges with steel truss girder are executed in this paper combined with several projects wich are being designed and constructed in mountainous areas southwest of China.The paper first reviewes the development of suspension bridge,it also summarizes the calculation theory for suspension bridge under various type of loads.Then structure characteristics of suspension bridge with steel truss girder,common deck department included, are illustrated,and construction methods for suspension bridges with steel truss girder are summarized.A method of "cantilever beam" used to calculate equivalent bending stiffness and torsional stiffness is proposed,and the accuracy of which is verified. To calculate the equivalent stiffness of truss girder,a simplified method based on the idea of "comparing to web" is introduced. The formula of the method is also derivatesd whose error is below 5.0%.Forthermore,the influencing factors of steel truss stiffness are discussed.By method of finite element calculation,parameter analysis of suspension bridge with steel truss girder are carried out. The influence on mechanical properties of suspension bridge with steel truss girder is discussed by those parameters,such as the ratio of edge span to main span of cable,the ratio of sag to span of main cable,the constant load of stiffing girder and central deduction,and some meaningful conclusions are derived..Finally, similarities and differences between suspension bridge with steel truss girder and suspension bridge with steel box girder are compared from the aspects of adaptability of double traffic and construction, the maintenance,the intensify effects of girder, as well as wind performance,and the adaptive building conditions for themselves are pointed out.