Study On Design Optimization Of Low Tower Cable-stayed Bridge In Coastal Area

Low-stayed cable-stayed bridges are new-type bridges that have developed rapidly only in the past two or three decades.They combine the characteristics of beam bridges and ordinary cable-stayed bridges,and have good development prospects.This paper takes Wangang Gangbei Bridge,a typical coastal area short-stayed cable-stayed bridge as the engineering background,and conducts the research on the force of different structural systems of the low-stayed cable-stayed bridge.Based on the structural system research,the continuous beam system is short.The seismic performance and wind resistance of tower cable-stayed bridges are studied in depth.At the same time,reasonable engineering measures are proposed for the durability design of bridges in high-corrosion natural environments in coastal areas.The research results have reference value for the construction of similar bridges.The specific content is as follows:1.Combined with the supporting projects,the design of the Gangbei Bridge was determined through the comparison of the static performances of the three systems of the continuous beam system low-stayed cable-stayed bridge,the rigid-framed low-stayed cable-stayed bridge,and the Y-shaped rigid-frame bridge.The maximum compressive stress of the normal section of the main beam,the maximum compressive stress of the inclined section,the crack resistance check of the normal section of the main beam,and the crack resistance check of the inclined section can meet the requirements of the code;the stiffness of the main beam is good.Comprehensively considered,the design of Gangbei Bridge adopts the continuous beam system low-pylon cable-stayed bridge scheme.2.The seismic performance of the bridge was studied for the short tower cable-stayed bridge with continuous beam system.Put forward the transition in the bridge piers and the main pier Settings JQZ(Ⅲ)steel ball bearing,the approach of using lead isolation rubber bearing design.When an earthquake occurs,in order to ensure the displacement of the bridge superstructure within the allowable range,the corresponding anti-falling beam device is designed between the main girder and the bridge pier to avoid the failure of falling beam.2.Research on the seismic performance of the bridge with the short-stayed cable-stayed bridge scheme of the continuous beam system finally adopted.The design scheme of setting JQZ(Ⅲ)spherical steel bearings at the transition pier and the main pier of the main bridge and using lead-core isolated rubber bearings for the approach bridge is proposed.When an earthquake occurs,in order to ensure that the displacement of the bridge’s superstructure is within the allowable range,corresponding anti-falling beam devices are designed between the main beam and the bridge pier to avoid falling beam damage.3.The wind resistance performance of the bridge based on the final solution of the short-stayed cable-stayed bridge with continuous beam system was studied.Based on the analysis of the dynamic characteristics of the bridge structure,and through the study of key parameters,the analysis shows that the bridge has no significant safety problems of stayed cable wind vibration,and there is a low possibility of strong wind vibration and cable wake vibration phenomenon.Under different wind speed values,the aerodynamic derivatives of the main girder with different wind speeds and different bridge states are obtained.The flutter stability analysis of the bridged state and the most unfavorable state during the construction period was performed using aerodynamic derivatives.The analysis results show that the bridge flutter wind speed is much greater than the flutter test wind speed in both the construction stage and the bridge formation stage.It has the enough safety reserves.4.Starting from the corrosion and failure mechanism of stay cables and reinforced concrete,the design criteria for durability of the supporting structure were determined,and stay cable and concrete anti-corrosion measures were proposed.