Analysis On Damage States Simulation For Continuous Rigid Frame Bridge And Research On Modified Structure System Enforcement

Continuous rigid frame bridge has had a wide application for works in recent years.However,excessive deflection in the mid-span appeared in numerous of continuous steel structure bridge.This paper analyzes damage sensitivity to Continuous rigid frame bridge and further studies the modification of structure reinforcement system(Extradosed cable-stayed system)in order to address the said issue.This paper also studies the influence that sensitive factors such as overload,pre-stressed reinforcement bar loss,main girder rigidity deduction,concrete shrinkage and creep,etc.may have on deflection of bridge span and up-down fiber stress through finite element and analyze main causes to main girder crack and excessive deflection in the midspan by lateral comparison analysis.It identifies status of existing force and defection value through measured data and selects appropriate combined condition to simulate the structure damage by combining of sensitive factor affecting down deflection and crack as well as deflection stress fitting process.Calculation analysis on force and rigidity for damaged bridge shall be done in accordance with specification and calculated result shall be the same with bridge disease which will be taken as calculation basis for bridge enforcement at a later time.The structure and material parameter are confirmed for extradosed cable-stayed system with reference of specification and actual bridge damages.It designs a practical and physical enforcement method statement through the principle being state of reasonable bridge,finds the relation between length of main girder without cables on the midspan and enforcement effect and comes up with the appropriate scope for main girder without cables on the midspan.The calculation analysis for enforced bridge shows that extradosed cable-stayed enforcement system can not only improve main girder and restrain cross the middle and lower torsion,but also keep the flexural torque and force of main girder in an appropriate status to achieve the substantially expected enforcement effect.