Influnce Of Vertical Prestressed Steel Anchor Backing Plate Installated Dip On Prestressed Loss

System of prestressed concrete continuum(steel)box-girder has applied widely and developed rapidly.With the increasing span,how to reduce and control the web main tensile stress has become an important content in the design of setting vertical prestressed steel in box-girder web.However, after setting the vertical prestressed steel,box-girder' web split is also existing widely.The greater loss of vertical prestressed is the main reason that makes box-girder' web split.Owning to less of the supports of theory and practice,especially disturbed by human's factors,it is difficult to build an effective calculating model for vertical prestressed loss.Human's factors which cause prestressed loss reflect such mainly two aspects:firstly,in the process of setting vertical prestressed,such phenomenons are very serious,for example:how to set fine rolled twisted bar unvertical and there is major mistake in anchor plate installing process.Secondly,it is common existed in not stretching enough in the process of tension,anchor adlibitum and nuts not tightening.Above mentioned two human operating problems will result anchor stress loss too great directly,even make prestressed failure.This thiese focuses on the research of the problem of reliability of vertical prestressed steel anchor plate installing.The major research contents are as follows:the main reason is whether the installing mistakes (install dip)of vertical prestressed steel anchor plate causing prestressed loss too great,and in the standard whether increases the prestressed loss when calculating vertical prestressed loss.In order to complete this thiese's research content,it needs from the two main aspects to research—the present situation of anchor plate installing mistakes and the loss quality by installing mistakes,and the concrete research content and methods are as follows: (1)According to the statistical survey of the available anchor plate fixing technology and construction level,a reliable and accurate dip angle distribution of anchor plate installation will be got.By using scientific research on how to prevent the participative box-beam split,six continuous beam prestressed concrete box-girder(continuous rigid structure),which are under construction,including Hunan province YiYang ChiShan Bridge, Yongsheng Bridge which belongs to TaiAo high speed road from GuangDong province ShunDe to ZhongShan,and so on,five long bridge,it will have a mathematical statistics on anchor plate installing dip angle's sample date,then will get a distribution probability function of anchor plate fixing dip angle,and satisfied structure reliability 0.95 which anchor plate installing angle is Z_p=0.95.(2)Room manufacture model,to research the influence of anchor plate dip angle's loss in lab.According to the real bridges' web sizes(Hunan province YiYang ChiShan Bridge),simulating the process of box-girder web vertical prestressed tension,a length 4m,height 4.5m and width 0.3m concrete test beam has been made in lab.The height of test beam adopt step way,according to the factual construction parameters,every 400mm will install a vertical prestressed system,the length of steel from 2m to 4m inequality.Meanwhile,fixing measuring force sensons wiil test the loss value of prestressed in different conditions of different installing dip angle, and test torque anchorage and the second tension's influence on the prestressed loss.