Effect of steel fiber distribution strategy on the cyclic performance of Multi-Layer lightweight concrete beams

The increasing demand for lightweight and ductile structural systems for seismic and cyclic loading applications has driven the development of multilayer lightweight concrete (LWC) beams with enhanced crack resistance and energy dissipation capacity. This study experimentally investigates the effects of steel fiber dosage and distribution strategy on the cyclic flexural behavior of multilayer LWC beams subjected to reversed cyclic loading. Five beam groups incorporating steel fiber volume fractions of 0, 0.5, 1.0, and 1.5% were evaluated using both uniform fiber distribution and selective outer-layer reinforcement configurations. The experimental program assessed load–displacement response, crack propagation, stiffness degradation, ductility, hysteretic behavior, backbone response, and energy dissipation capacity under cyclic loading. The results demonstrated that steel fiber reinforcement significantly improved the structural performance of multilayer LWC beams by delaying crack initiation, limiting crack propagation, and enhancing post-cracking resistance. Compared with the control specimens, the incorporation of 1.0% steel fibers increased compressive strength by approximately 35% and splitting tensile strength by nearly 63%. Under cyclic loading, beams with 1.0% uniformly distributed fibers exhibited the most balanced structural performance, achieving increases in tensile load capacity of approximately 60–70%, along with improved ductility and energy dissipation capacity.