The Low Pre-stressed Technique And Its Application In Bridge Research

Along with the increasing application of the reinforcement concrete in the work,people have more profound knowledge to the partial prestressing concrete.But people mostly attempt the partial prestressing concrete on the basis of the full prestressing concrete,resulting in the prestressing value is still "high". Generally the prestressing value is a percentage of 70-90 of the full prestressing concrete.But relative to the "high"prestressing concrete , the "low"prestressing concrete is still in the stage of having buds.Thus we need an in-depth study about it.Taking Xiaoxi Bridge as an example,the thesis brings forward the economical ,simple ,construct-convenient ,light-tonnage prestressing technique.According to Yi'an bridge in Chongyi,on the twenty-meter long beam,certain load, the low prestressing concrete takes a all-around contrast with the full prestressing concrete and steel-reinforced concrete. As the low prestressing concrete has a low prestressing value,in Xiaoxi Bridge we takeφ32 precision twisted steel as prestessing steel and we stretch it using electric warming.The method of electric warming has the advantage of simple equipment, convenient operation,high manufacture efficiency etc.It is fit for light-tonnage strain technique in the low prestressing concrete especially.In Xiaoxi Bridge it is successful to pull the prestressing steel using electric warming. In the static test on Yi'an Bridge in Chongyi,we take a detailed examination and analysis about the flexivity,reinforcement stress,concete stress,steel wires stress of the steel-reinforced concrete,the low prestressing concrete and the full prestressing concrete on the twenty-meter long beam.We have a particular compare in the mechanical property and the economy property to the three spans. In a certain span beam that allows crack,the low prestressing concrete is more economic,reasonable compared with the full prestressing concrete and the steel-reinforced concrete.And its construct technics is more simple,convenient,safe.As the incessant,in-depth study in the theory and construct technics of the low prestressing concrete,the low prestressing technology will obtain more and more extensive application in the engineering practice.