DEFORMABILITY OF STEEL REINFORCEMENT OF DAMAGED CFRP-STRENGTHENED BEAMS UNDER THE ACTION OF CYCLIC LOADING

Abstract

 In the article are presented the main results of experimental studies of deformability 
of the reinforcement of common damaged and brought, in the course of the previous tests, to the 
critical state by the 1st group r.c. beams reinforced with carbon  fibre (CFRP) sheet in the lower 
tensioned zone and on the support area.  
Namely, according to the results of the experiment, using the COMPEX program, adequate 
mathematical models of the deformations of steel reinforcement of CFRP-strengthened reinforced 
concrete specimens-beams under the action of low-cycle sign-constant loading were derived, that 
reflect the influence of these factors both individually and in interaction with each other. Analyzing 
these models, the features of the development of tensile reinforcement in the specified conditions, 
were established. In particular, the factors that have the greatest influence on deformations are the 
relative  shear  span  and  the  level  of  low-cycle  loading.  As  compared  with  the  series  of  tests  of 
ordinary  r.c.  samples,  presence  of  the  external  CFRP  strengthening  reduced  deformation  of  the 
tensioned steel reinforcement by 1.65 times on the average. There occurs a re-distribution of the 
tension forces between them.