Test And Research On The Frictional Loss Of Prestress In The Corrugated Pipe Duck

Paper Title:Test and research on the frictional loss of prestress in the corrugated pipe duckBrief Introduction of Author:Zhang Di Long,male,born in Feb.28,1981.Master Graduated From China Academy of Building Research.Speciality in Structure Engineering.Supervisor Is Prof.Di Xiao Tan.In the post-tensioned prestressed concrete structure,loss of prestress arising from the main factors is:deformation of anchorage at stretching end and inner shortening of steel bar,friction of prestressed teel reinforcement with duct wall,stress relaxation of prestressed steel reinforcement,shrinkage and creep of concrete,for ring-shaped members using spiral prestressed steel reinforcement,resulting from local compression of concrete,and so on.Particularly on Long-Span,the long curve of the prestressed concrete structure,one the friction of prestressed teel reinforcement with duct wall of the large proportion of loss.The values for loss of prestress on friction of prestressed teel reinforcement with duct wall,the exact formula of domestic and international norms are given is basically the same,but the coefficient of frictional factor of strand and its duckμand deviation factor of strand ductκis different.Set aside duck commonly used by embedded corrugated pipe,and there are metal corrugated pipe and plastic.The friction coefficient of metal corrugated pipe has been provided in the "Code for design of concrete structures"(GB 50010-2002),but the friction coefficient of plastic corrugated pipe has not been provided.Both of them have been provided in the "Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts"(JTG D 62-2004).Previously identified parameter values at home and abroad is a indirect method. It is used to test components in a straight line on the statistics of the beamκvalue, then the use of statistics to theκvalue in the curve of statistics on the beam to theμvalue.But there is no linear beam in the actual work.Over the years,the China Academy of building research Building engeering Test Center has test a large number of friction coefficient of corrugated pipe duck and accumulated a wealth of data.After the statistical analysis on the data,the actual friction coefficient of the corrugated pipe is direct determined.Thus,the provided friction coefficient values in the relevant norms are verificated,at the same time,this paper give a suggestion about the value of the friction coefficient of plastic corrugated pipe for the "Code for design of concrete structures".