Static Test And Effective Prestress Detection Methods Of A Damaged Prestressed Concrete T-beam

The effective prestress existing in a prestressed concrete bridge member is acrucial factor for bridge service safety and working life,once there is too muchprestress loss in a bridge member,the bridge may have a sudden brittle fracture andhave some disastrous results.In recent years,the damage precdiction and maintenanceand reinforcement techniques are getting more and more attention from theengineers,once finishing destruction the prestress will serve as an inter force in astructure,it’s hard to detect it directly,so it’s difficult to judge the effective prestress inprestressed members,while identification the effective prestress has importantengineering meaning for the operating department in making proper maintenance andreinforcement decisions.The changing beam work were did in some bridge from the Jingtong Line in2012,the two old prestressed concrete beams,which has a span of23.8m,providegrete chance for studying the project “Study on Service Behavior and Determine ofEffective Prestress in Existing Line Prestressed Concrete T-beams”.In this paper,wedid static load test,decompression load test as well as concrete stress relief test in oneof the old beams,identified and computed the effective prestress in the beam,thefolling are the main contents:Firstly,summarize the existing home and abroad papers about effective prestressdetection method in presressed concrete member,and force on analyzing thetheoretical foundation and application and development of the concrete stree reliefmethod.Secondly,use the software ANSYS to establish a FEM model for the testingbeam,and get the conclusion that when the neighbouring grooves are10cm apart fromeach erther,the grooves are30cm long and the depth are3cm,we could have thestress relief in the concrete.Thirdly,full-scale test were did on spot,the prestress loss is26.48percentagedetermined by the decompression load test results,and the stress relief test results show the loss is18.24percentage,while according to the current specification theprestress loss in the beam is28.86percentage.The research achievement in this paper could provide the basis for the servicedepartment to evaluate the service behavior as well as to finish the maintance andreforcement job of the same kind of beams.