 This study investigated the effects of using bottom ash as a replacement for fine aggregate in reinforced concrete beams. It was found that 75% bottom ash ratio produced the best results in terms of displacement capacity. Additionally, increasing the bottom ash ratio to 100% resulted in a decrease in deflection capacity. Furthermore, the study used ANSYS software to build 3D finite element models, PHEMS, of beams to compare with experimental data. The PHEMS accurately predicted the flexural and fracture behaviors observed in the experiments. Finally, the study concluded that the use of bottom ash as a replacement for fine aggregate can significantly reduce the weight of the structure, increase the number of columns and reinforcing bars, and improve the strength of the structure under both close and far-fault earthquakes. This article was authored by Memdu Keralar, Turhan Baylor, Marat Kavuslu, and others.