Research Of Prestressed Concrete Beam And Long-term Performance

Many factor that affect the long-term performance of concrete, shrinkage and creep of prestressed concrete beams have great effect on the long-term performance, especially sensitive to creep effect of prestressed structure, although the structural analysis of prestressed concrete beam, calculation theory and method for decades of practice and theory research, but the forecast and control the influence of various factors on the structure performance is complex and difficult to obtain accurate answers. How sensitive structure more accurate analysis of creep deformation for a long time, choose the appropriate creep model, using accurate creep theory, improve the precision of numerical analysis method, is a problem concerned by scholars at home and abroad.Paper chooses a four layers framework structure of floor and27m single span beam as the research object, the large-span prestressed beam structure design and analysis of the basic principles of its application in practical engineering are expounded. For27m span prestressed concrete beam, this paper chose three cross section design, specification method preliminarily determines the amount of reinforced prestressed concrete beams, and then to its carrying capacity, seismic performance, crack and deflection calculation, final three beam of prestressed reinforcement and common reinforcement of consumption. Finally, through the calculation of creep on the influence of three kinds of beam cross section deflection, and the three kinds of beam cross section in the long-term deflection, this paper compares and analyzes the related conclusion:when using the stage for a long time, with the increase of age of concrete, the same cross section deflection of concrete increases speed will be more and more small; The different cross section, in the same age, section deflection of small, small cross section of the large deflection; Different cross section, the large deflection of slower growth, small cross section of fast growth. Three section from small to large, using phase short-term deflection were9.43mm,5.38mm and2.20mm, small cross section and large cross-section of short-term deflection difference of7.23mm; Using phase long-term deflection of20.00mm,10.11mm and4.05mm respectively, small cross section and large cross-section deflection differential value of15.95mm. The long-term deflection of small beam reached2.05times of short-term deflection, large long-term deflection for short-term deflection of the beam are1.8times. This paper not only introduces the structure design of large span prestressed beam, but also analyzes the different cross section under the long-term performance of long-span beam, for later design of large span prestressed concrete beam and the long-term performance of the research provides a certain reference.