The Research Of The Springing Quantum Control Of Prefabricated Prestress Concrete Beams

With the continued development of national economy, the government has increased the investment of basic establishment and China's highway has entered the phase of expressway building. In virtue of the particular advantages, the prestressed concrete structure has developed rapidly for recent tens of years. But the excess the springing quantum of the PC beam due to continued evolution of concrete creep, which influenced the normal performance of structure, has been an important question puzzling the engineering technicians all the while.The springing quantum of the PC beams due to the beforehand stress is only part of that of girder. The time is longer, the measurement of the springing quantum of the PC beams due to concrete creep is bigger. The fact has proved that 60~70 percent or more the springing quantum of the PC beams of girder is caused by concrete creep if the influence of creep is out of control or controlled incorrectly. Further more, the prestress loss , which is caused by the shortened beam member due to concrete shrink and creep, is of disbenefit to prestress concrete structure. Hence, in order to guarantee the engineering quality, we must reduce the concrete shrink and creep furthest in constructing and design.Aiming at the right control method of girder the springing quantum of the PC beams, analyzing the major factors which influence the change of girder, establishing control measures, observing and researching through experiment, the thesis make some pilot studies in Liuguhe Bridge's beforehand producing, building up and constructing, which belongs to the eighth contract segment of the Beijing to Shenyang expressway.