Research On The Ultimate Moment Capacity Of Externally Prestressed Composite Beams With Corrugated Steel Webs

The development of external prestressing technology promoted the organic combination of external prestressing technology and steel-concrete composite structure. As a new kind of external prestressed composite girder bridge, the composite girder bridge with corrugated steel webs adopts thinner corrugated steel webs instead of the thicker traditional concrete webs, by using external prestressed tendons instead of bonded prestressed tendons in webs, it has much more obvious advantages of structure,such as reducing the weight of structure, having clearly mechanical state, avoiding web cracking permanently and so on. So it has grown rapidly at home and abroad. The research on this kind of bridge at home and abroad is also very much, such as the bending performance, the shearing performance, the torsion and distortion performance, the mechanical performance on shear connectors between concrete roof and floor with corrugated steel webs and so on. This article has carried on the theoretical analysis and experimental research on the bending properties of this kind of structure, especially on the stress increments of external prestressed tendons, the main content of this article includes:(1)Reviewed the development history and present application of externally prestressed concrete bridges. Described the bending mechanical properties of externally prestressed concrete girders and corrugated steel web composite girders. Summarized the research methods on externally prestressed concrete structure at home and abroad and the calculation formula of ultimate stress on external tendons.(2)Flexural tests of two externally prestressed composite girders with corrugated steel webs were designed and completed, and by using the nonlinear finite element program and the Open Sees model of the test model analysed the whole loading process, analyzed the mechanical properties of bending process on the composite girder bridge with corrugated steel webs, discussed the stress increment of external tendons in bending process, the results of numerical analysis are agree well with the test results.(3)Described the method of programming external prestressed concrete griders model or composite griders model with corrugated steel webs by using Open Sees. And the correctness of the method was demonstrated. Through the method of building plane frame model can analyze a large number of parameters, and it's convenient and practical.(4)Based on Lin Jiaba bridge, the numerical analysis model was built by using Open Sees software, and study the factors influencing the stress increment of external prestressed tendons in ultmate state. Based on this, the simplified calculation formula of ultimate stress increment was fitted, which considered the span depth ratio, the ordinary steel reinforcement ratio and the efficiency of the prestressed steel reinforcement. And the formula was tested by 22 groups of test data.(5)According to the standard interpretation, combined with the analysis of test and parameters, recommended the ultimate stress increment of external tendons is 200~300MPa. Thus can use a simplified calculation method to calculate the bending bearing capacity of composite girder bridge with corrugated steel webs and externally prestressed tendons.