The Bearing Capacity Analysis Of External Prestressed Continuous Composite Steel-concrete Beam Structure

In this paper,the stress,displacement and failure state of external prestressed continuous composite steel-concrete beam structure are studied under vertical concentrated loads.Simple formula of bearing capacity of midspan and pivot at ultimat state is also presented.Numerical simulate analysis is done and the adviced section size is also given in the paper.It includes 6 chapters.Part 3 and Part 4 are important and Part 4 is the hardcore of this paper.Chapter 1 is mainly introduce the primary formats, characteristics and the using scope of the combination configuration and prestressed combination configuration,then introduce the development and research status of the prestressed continuous composite steel-concrete beams. This chapter is also talk about the study purpose,study content,study method and the conclusion of the study.The second chapter is the flexibility analysis of external prestressed continuous composite steel-concrete beam through the Finite Element Method software-MIDAS/CIVIL. In this part,the prestressed reinforced steel bar is simulated by the Construction Stages which is provided in the program.Besides,in virtue of the program offering the unite sectional forms , it makes the calculation more convenient and accurate . Finally , according to the stress we can estimate that when the force is in the range of 45t to 50t,the beam structure is yielding,and when the force is about 60t,the structure would be destroied .The third chapter is the emphases of the paper , in this part we use ANSYS to simulate the external prestressed continuous composite steel-concrete beam. And also consides the non-linear characteristics of steel and concrete.Concrete use the MISO model,don't conside the failure principle;Steel beam and steel bars use the BKIN model, yield intensity is 345MPa.We think that when the concrete and steel beam have reached to their Ultimate Strength,the continuous composite steel-concrete beam would be destroied.In this part we use the load step to simulate the force which is loading step by step.Using the path to check the changing of stress which is in the steel beam and also check the stress of concrete,proving the hysteresis of shearing force.Finally,we use the F-D curve,S-Tcurve to confirm the bearing capacity of the external prestressed continuous composite steel-concrete beam is about 62t.In chapter 4, the ultimate capacity formulation of steel-concrete beam is deduced from the plastic theory,it is also the hardcore of the whole paper.We assume that when the continuous composite steel-concrete beam is destroyed ,the intensity of concrete and steel beam is also reach to their Ultimate Strength.Then we deduce the formula for bearing capacity of midspan and pivot. We use this bearing capacity formula to calculate the continuous composite steel-concrete beam which is the model in the third chapter,the result of the bearing capacity is 65.7t.It is close to 62t which is the result of ANSYS program.So we think the formula is reliable.In chapter 5 we analyse the section size infection of the continuous composite steel-concrete beam by programming .Through changing the size of concrete,and changing the size of steel beam and changing the both size of concrete and steel beam,we get the rule curves of bearing capacity.Chapter 6 is the summary of the paper in which the study content and direction are also pointed out.