INNOVATIVE DESIGN OF FRP COMBINED WITH CONCRETE - LONG-TERM BEHAVIOR

The time-dependent behavior of a new class of hybrid elements consisti ng of glass-fiber-reinforced-plastic (GFRP) box beams combined with a layer of concrete in the compression flange and a carbon-fiber- reinfo rced-plastic laminate (CFRP) as additional tension reinforcement is pr esented in this study. Shrinkage, creep, and fatigue models for concre te are combined with creep and fatigue models for GFRP (based on both laminate theory and semiempirical approaches) to yield a general analy sis procedure for predicting the deformation and residual strength res ponse of hybrid GFRP/CFRP/concrete beams subjected to sustained and/or alternating loading. The analytical model predictions are compared wi th experimental results obtained from creep and fatigue testing of lar ge-scale members, giving very good agreement. The present study shows that the new hybrid beams possess very good time-dependent response ch aracteristics, and the models described here, along with those given i n the companion paper for short-term behavior, can be used as analytic al tools for the optimum design of such members under both short-term and long-term loading actions.