Measurement And Assessment Of Prestress Loss In Hu Jiagou3#Bridge

First of all, by searching the literatures and informations, knows the current development status condition of reinforced concrete and the research progress condition of prestress loss. However, some serious problems emerging in prestressed concrete continuous girder bridge, such as box girder fracture, excessive midspan deflection and so on. These problems is, to large extent, on the account of insufficiency of effective prestress. The estimation shortage of loss of prestress in design and non-standard construction are the main course for excessive loss of prestress. For prestressed concrete continuous girder bridge, the influence factors on prestress are numerous and the estimation of effective prestress can hardly match the actual effective prestress. The completed status of bridge can hardly agree with the actual status theoretically. Thus, safety loophole emerges, the service life becomes shorter. So the research on loss of prestress is a matter of great account.We refer to "Reinforced Concrete and Prestressed Concrete Bridge Design Specifications" and other various specification and we also use Midas/Civil for modeling analysis on the project on the Hu Jiagou1st bridge, in order to get the theoretical data. Then we obtain the real-time measured value of the loss of prestress from the pre-embedded anchor load on the8th pier of this bridge and analyse the actual and theoretical value of the loss of prestress. Put the actual loss of prestress combination back to the model to access the actual status of the completed bridge. Finally, we compare the completed status of bridge in actual prestress loss with the theoretical one. From this research, we verify whether the estimation of loss of prestress corresponds with the actual status and also we study the influence of loss of effective prestress on completed status of bridge. This research has significant meaning on the loss of prestress of prestressed concrete bridge and shows guidance for the design and construct of prestressed concrete bridge. Results are as follows:①The measured values and theoretical calculated values of prestress is similar in the trend of the attenuation law, but the former is lower than the theoretical calculated value by74.14MPa.②Due to the loss of prestress measured value is greater than the calculated value, the bending moment of the control point of closure section of the bridge increased significantly, up to more than4000kN·m, it will do a great harm to the bridge structure. ③Due to the loss of prestress measured value is greater than the calculated value, the vertical displacement of the control point of closure section of the bridge increase about2mm, which cause significant impact on the bridge line shape of the bridge structure.④In the case of large loss of prestress (prestress loss is50%), the value of the bending moment of the point of midspan closure section and the side span closure section increased significantly to28.27%, it is bad for the bridge structure, the vertical displacement of the control point of closure section increase about7mm, which cause significant impact on the bridge line shape of the bridge structure.