The Influence Of Prestress And Damage On The Dynamic Characteristics Of Concrete Simply Supported Beam Bridges

With the existence of prestress and damage,the static and dynamic characteristics of concrete structures will be changed. There were lots of depth researches and reasonable conclusions in the static effect of structure,But the prestressing and damaging effect on dynamic characteristics of the structure and damage research is relatively less, and have not yet obtained a unified conclusion. Based on Practieal engineering,this paper around the supported of beam bridge dynamic vibration characteristics, both theoretical research and analysis of finite element simulation were carried on impact of dynamic characteristics of the concrete bridge.Firstly,This article theoretically deduces formula for natural frequency of Prestressed concrete beam bridge under uniformly distributed force, and discusses its all influencing factors.because of the structure damage is bound to affect the bridge stiffness, so further deducesthe natural frequencies formula of prestressed concrete beam bridge with damage or cracks.The nnumeric analysis of the dynamic Performance of Yongwen crossing Bridge was carried out by general finitesoft ware ANSYS,the results showed that the frequencies go up with the Prestressingf orce,but the influence was little when Prestressing force is small.Finally, by introducing damage variable, frequency drop, modal assurance criteria MAC from the damage location, the extent of damage, crack location, crack depth and using theoretical method and ANSYS to examine the injury on Natural Vibration Characteristics.The purpose of this paper is to discuss whether the Yongwen crossing bridge simplified model is reasonable,by theoretical research and analysis of finite element simulationdrawn a conclusion that the influence of prestressed was little, while the larger impact of local damage to dynamic vibration characteristics, and provided evidence for practical engineering structures.