Calculation and Analysis on Flexural Strengthening with CFRP Laminate Considering the Preexisting Strain

The preexisting strains of structures have some influence on the efficiency of CFRP Laminate. Based on the analysis of the abundant existing research productions, the calculation formulas of CFRP Laminate are proposed based on the supposition of plane section and balance of forces considering the preexisting strain. And the formulas are easy to understand and master for designers. By discussing the relation between the preexisting strain and relative depth of compression area, the essentials of the impact on reinforcement effect of residual strain are confirmed. The results can offer reference bases for strengthening engineering design with CFRP.