Test Study On Bearing Ability Of Simply Supported External Prestressed Steel-Light Weight Concrete Beam

The application of prestressed steel-concrete composite beam develop swift in our country in recent years.It is applyed in meny large structure. Lightweight aggregate concrete is a new style concrete which is applyed widely in our country in recent years.The lightweight aggregate concrete is fine in performance and exceed normal concrete at a great many aspect. A excellent structure and a excellent material combine in my investigative content of my article-- line reinforce vitro prestressed steel - lightweight aggregate concrete combination freely supported beam.This article mainly researched strain, displacement and collapse behaviour of straight reinforced vitro prestress steel - lightweight aggregate concrete combination freely supported beam under the action of monotone single load.We analyses strain distribution change rule of midspan and L/4 section, glide strain difference of steel - concrete interface, change instance of prestress steel bundle along with load, change instance of beam deflection came along with load, stress redistribution instance of steel beam lower flange.And analyses the cause of the a series of stress behavior of combination beam. The full article divides into six chapter.The point is chapter four and five.The first chapter introduce research actuality and research value of this article.The feasibilit application of lightweight aggregate concrete in combination beam is new development of composite structure.Characteristic of lightweight aggregate concrete is the key applyed to have application in combination beam.This chapter introduce characteristic of lightweight aggregate concrete and its current status both here and abroad, analyses long term potential and apply value of lightweight aggregate concrete. On the base of lightness quality, good viability, good earthquake-resistant behavior and good economic returns, lightweight aggregate concrete could fully exert inherent advantages of steel and lightweight aggregate concrete applying to combination beam.By testing technical characteristics of prestress steel - lightweight aggregate concrete combination beam,we analyses apply predominance of prestress steel - lightweight aggregate combination beam.Lightweight aggregate concrete bore favorable feasibility and better apply predominance applyed to steel-concrete composite beam.The second chapter introduce foundation service test of this material.This experiment fix the best optimum mix of this lightweight aggregate through orthogonal test. The experiment design base mixture ratio of lightweight aggregate concrete after fixed relevant parameter by the method of loose volume law.The experiment the technology of beforehand h waterretaining.We design four-factor and three- level perpendicular experiment based on the base mixture ratio.We select a best mixture ratio according to compressive strength of cube specimen.But later we found the mixture ratio can not met the require of engineering practice because of the smallness of caving degree.So we make another analyses of testing data and select the second mixture ratio as the best mixture ratio.The third chapter mainly analyses carrying capacity of prestress steel - lightweight aggregate concrete combination beam. This chapter analyses carrying capacity and stress behavior of combination beam by method of resiliometer algorithm and plastic theory.The stress behavior include strain distribution change rule of midspan and L/4 section, glide strain difference of steel - concrete interface, change instance of prestress steel bundle along with load, change instance of beam deflection came along with load, stress redistribution instance of steel beam lower flange,and so on.The result will be referenced in experiment and finite element modelling.The fourth chapter is the main portion of this article which introduce experimentation and experiment content of monotonic symmetric loading experiment.We analyses testing result and derive some valuable conclusion: (1)The strained condition of normal section conform plane section postulate when load si smaller but disagree with plane section postulate when load si bigger.So we would consider non- plane section factor and carry out relevance amend in computing mechanism.(2)The shearing force stagnant phenomena presence in concrete flange and be complex nearby shearing force bond(.3)The shorn slippage of steel - concrete interface is distinctness in shear zone,the mix is at the middle of loading point and pivot. Shearing force stagnant phenomena effect combination effect,so it would be regarded in research anddesign henceforth. (4) Application of prestress can decrease maxima longitudinal stress of girder tip and breast which control carrying capacity of combination beam. So prestress can advance carrying capacity of combination beam.(5) Plasticity twist is formed at loading point when load is bigger,so weshould consider fully the impact of material plasticity to structurl safety.The fifth chapter introduce finite element modelling analyses of combination beam,built rational finite element model of combination beam.We contrast analogue result and experiment result. Analyses combination beam apply this model can get reliable data.The sixth chapter is whole-length summarize.This chapter made a summarize and generalize of work and harvest of this article and put requires and aim of henceforth research.