In historic objects, timber beams are often heavily damaged due to various reasons and demand
sanation or strengthening. In structural engineering, various applications of fiber composite or steel
reinforcement have been developed in order to achieve higher values of timber beam flexural stiffness
or strength. Based on the existing research papers we designed our research plan in order to evaluate
the influence of reinforcement on full-scale specimens with different reinforcement configurations.
Besides FRP reinforced beams, two beams were reinforced with longitudinal steel strips and tested for
comparison. To compare the reinforcement effectiveness, we additionally conducted the four point test
on bare timber beams. All of the specimens were tested using standard four-point bending test to
capture the beam deflections for elastic moduli evaluation. Flexural strength values of the tested
beams were determined based on the failure loads. The comparison of obtained values led us to
evaluate the optimal reinforcement configuration and showed us how each configuration influenced
the stiffness or strength of the beam. A simplified analytical model of non-linear plastic behaviour is
presented and implemented to calculate bending moments at which failures of strengthened beams
occur.
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