A new design approach for predicting the required lap-splice length for new generation GFRP bars in concrete members under reversed cyclic loading

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Currently, there is no available design method for lap-splicing the new generation of Glass Fiber-Reinforced Polymer (GFRP) reinforcing bars in concrete under reversed cyclic loading. This limitation restricts the use of these bars in scenarios where they are subjected to cyclic loading. This study aims to fill this gap by introducing a novel design methodology to predict the lap splice length of new generation GFRP reinforcing bars for concrete structures under reversed cyclic loading. For this purpose, eight full-scale building concrete columns reinforced with lap-spliced GFRP bars were tested—including one with continuous bars and seven with lap-spliced bars—under combined axial and reversed cyclic lateral loading. Additionally, seven specimens from the literature were included to expand the experimental database. Comparison with the experimental database indicated that the conventional approach used in in ACI 440.11, CSA S806 and JSCE for monotonic loading can underestimate lap-splice length under reversed cyclic loading by 42 %, 33 %, and 36 %, respectively. Therefore, our study developed an alternative procedure that considers the actual bar stress and incorporates the effect of the moment gradient, rather than assuming a uniform moment distribution along the splice region. Validation of the proposed procedure using experimental results from this study and the existing literature affirmed its accuracy in predicting the required lap-splice length for new generation GFRP reinforcement in building concrete members under reversed cyclic lateral loading.