Further Study On The Existing Stress Test Of Prestressed Hollow Slab Bridges Based On Stress Releasing Method

The existing stress of the prestressed concrete bridges is the key parameter to reflect safety perfomarce of structure. Owing to impacts from prestressed loss, concrete shrinkage & creep, structural damage, etc.There would be considerable differences between the theretical and pratical value of the existing stress of bridges. Severe loss of the prestress will affect the structure's performance and lifespan, and even cause security incidents. The existing stress test of bridges is still a difficult technical problem at present.Based on lots of papers at home and abroad, the thesis takes a prestressed concrete hollow slab bridges with 10 meters as a studying object to analyze and test by finite element calculation and interior model. The main studying results obtained as follows: With stress releasing method to ordinary steel bar, analysis by finite element calculation shows this. The peeling concretes' width and the depth are bigger and the unit of the steel bar's stress is increased bigger. The peeling concretes' length is longer and the unit of the steel bar's stress is been smaller.It can obtain the comprehensive elastic modulus of hollow slab for 4.56×10~4MPa with dynamic stiffness and static stiffness method, which measurement error is about 40% compared to standard reference of the concrete elastic modulus for 3.25×10~4MPa.It can obtain the concrete stress releasing coefficient for 0.47~0.60 through concrete stress releasing test in the bottom of hollow slab with the grooving method. However, having modified the concrete stress releasing coefficient for 0.85~1.09, the result of stability becomes better.With stress releasing method to ordinary steel bar of the ledger wall, it can obtain the stress releasing coefficient for 0.55~1.62, which is so discrete.