Shear Strength of Lightweight Concrete Structural Elements Reinforced with FRP Bars: Experimental Studies vs. Code Predictions.

Using lightweight concrete (LWC) reduces the dead weight of the concrete structure by 25-30% compared to ordinary concrete. However, harmful and corrosive substances penetrate the lightweight concrete matrix due to its high permeability, resulting in higher maintenance costs and a reduced structure service life. Therefore, in harsh environments where conventional steel bars are susceptible to corrosion, fibre-reinforced polymer (FRP) bars should be used for reinforcement. However, there is a paucity of experimental studies regarding LWC structural elements reinforced with FRP bars. Shear strength is a critical limit state that typically determines the proper design of such elements, ensuring the required safety margin and an appropriate level of reliability. The research work was conducted to compare the experimentally determined shear strengths (V) of 50 structural elements (beams, slabs) made of LWC/FRP with code predictions (V) made according to eight codes used for design. Based on this comparison, the so-called conformity coefficient (V/V) was calculated and used to assess which provision documents are the best, considering the entire population of test results. The work demonstrated that the recent Eurocode best predicts the shear strength of LWC/FRP elements.