Finite Element Analysis of Internal Forces in a Multistory Reinforced Concrete Building

This study performs a detailed finite element analysis of internal forces, displacements, and reinforcement requirements for a ten-story reinforced concrete (RC) building using ETABS software. The structural model was developed in accordance with Vietnam’s national standard TCVN 5574:2018. The building has a total height of 38.3 m and a typical floor height of 3.8 m. The system consists of RC moment-resisting frames with typical beam sections of 300 × 700 mm and column sections of 700 × 900 mm at lower floors, reduced in upper levels. Concrete grade B30 and reinforcement steels CB400-V (longitudinal) and CB300-T (stirrups) were utilized.Dead load, live load, finishing load, masonry wall load, and wind loads (converted to equivalent static forces per TCVN 5574:2018) were applied. Fifteen load combinations covering both ultimate and serviceability limit states were analyzed. The FEM model provided comprehensive results on bending moments, shear forces, axial loads, story displacements, and inter-story drifts.Analysis results indicate that the maximum roof displacement under wind load is 0.088 m, which satisfies the allowable limit of h/500 (0.0766 m). The maximum inter-story drift ratio is well below the code limit of 1/500. Critical internal forces reached 537.38 kNm (beam support moment), 373.07 kNm (mid-span moment), and up to 6092 kN axial compression in columns. Reinforcement design was performed accordingly, yielding economical steel ratios within code limits.This research highlights the effectiveness of finite element modeling as a powerful process simulation tool in structural engineering. It enables accurate prediction of structural behavior, optimization of material usage, and ensures compliance with safety and sustainability requirements for multistory buildings in Vietnam. The methodology demonstrates strong potential for integration into modern digital design and construction processes.