Study On Optimization Design Of Concrete Continuous Rigid Frame Bridge Main Beam Bottom Slap Prestressing Tendons

The continuous rigid frame bridge are favored by traffic engineering because of its many advantages since its appearance,in the course of many years of operation although there have been some diseases,these still can ' t shake its main position in the choice for the larger span bridge on the road and rail,what which mainly makes the engineering academic concern are the main beam cracks and long term deflection in the main span,these cracks include cracks in the bottom slap or concrete collapse,which makes the long term deflection in the span more bad,then influencing the safety and usability of bridge structure,using the level or bent layout of prestreding tendon can effectively solve the problem of bottom slap cracks and improve the adverse conditions of long term deflection in the main span,this paper focuses on the new layout of the bottom slap prestressing tendon to carry out the following research:1?The history and the latest development trend of continuous rigid frame bridge are introduced,the main diseases of continuous rigid frame bridge—long term deflection in the main span of main beam,main beam body cracking and bottom slap prestressing tensioning beam split are concluded.2?To summarize the commonly used values and ranges of the upper and lower structure design parameters and the conventional layout space prestressing tendon of the continuous rigid frame bridge,and list the measures of preventing and controlling the related diseases from the view of optimization.3?Combining with the real engineering example—MaGuoHe long span bridge—to study the optimal beam structure which accommodate bottom slap all prestressing tendons are arranged horizontally,six different optimization schemes were designed to compare long-term deflection,the internal force and stress of these scheme from the perspectives of long-term and short-term situations to find out the optimal scheme for the horizontally arrangement of all bottom slap prestressing tendons.4?Based on the same actual project and in the same way,this paper studied the optimal scheme which can adapt horizontally layout of partial bottom slap prestressing tendons.The optimal scheme whose all and partial bottom slap prestressing tendons are arranged horizontally were compared and analyzed in terms of long-term deflection,internal force and stess.5?This paper demonstreted the feasibility of the horizontally arrangement of the bottom slap prestressing tendons from the following three aspects—the economy analysis of the material usage and difficulty in construction,the partial stress analysis of the beam which include horizontal anchored partitions and anchorage zone,the investigation and analysis of a being running continuous rigid frame bridge whose all bottom slap prestressing tendons are arranged horizontally.6?This paper discussed the bridge concept design whose bottom slap prestressing tendons horizontally and vertically bend were removed,summarized the main beam structure and corresponding applicable span whose bottom slap prestressing tendons could be arranged in a horizontal arrangement,the upper bending arrangement,the double layer and the multi-layer bending arrangement,proposed the main beam conceptual design of the bottom slap prestressing tendons horizontally and upper bending arrangement of open-web continuous rigid frame bridge.