Influence Of Design And Construction Errors On Prestress Performance

Prestress is the lifeline of prestressed structure. Relaxation of the prestressing steelhas tremendous influence on structural long-term performance. The present research onthe relaxation of single prestressing wire/strand is already quite mature. However, inrealistic structure a prestressing steel tendon is usually used in form of a bundle whichcomprises multiple wires/strands, the initial anchoring stresses of all the wires/strands ina bundle are uneven. Since the relaxation ratio of prestressing steel is very sensitive toits initial stress, effect of non-uniform distribution characteristics of initial stresses in aprestressing steel bundle on the prestress loss of the bundle is still unclear.①This paper describes the current two control methods: prestressed tensiontechnology status and prestressed tension control, as well as the problems in theprestressed tension construction technology and the existence of the hidden in theprestressed tension quality（the same bundle prestressed non-uniform and the samecross-section non-uniform）, and pointed out the impact of prestressed relaxation losscalculations by the same bundle prestressed non-uniform.②Based on the effective prestressing measured data when prestressed tendonstensioning anchored in the construction site, applying a random number generator waysto simulate the non-uniform distribution characteristics of the initial stress whenprestressed tendons anchored. We study the non-uniform prestressed tendons relaxationloss by making use of a single prestressed tendons relaxation loss law, calculations: therelationship between the ratio and dispersion coefficient, the ratio is the singleprestressed tendon calculated relaxation loss by the total calculated average initial stress,and using polynomial fitting.③This article will apply the researched results calculated by non-uniformprestressed tendon relaxation loss to the actual continuous rigid frame bridge, usingdoctor bridge to model and calculate. We convent dispersion coefficient characterizedby the unevenness of prestressed tendon bundle to prestressed relaxation, then in thisway calculate the model, watching different construction stage each controlling sectionthe up and lower corresponding, includes: unit stress, the structure cracking momentand the structure displacement under the shrinkage and creep.④This article describes the effective prestressed detection systems and prestressedconstruction quality inspection and assessment systems,as well as the design standard of detection, we propose remedial measures for the failure of prestressed tendon. Inaddition, we suggest a new system to comb compiled wear bundle for the the samebundle and the unevenness of prestressed tendon, which have been verified in the actualbridge.