This paper explores the application of Inelastic Nonlinear Buckling Analysis (INBA) with Stiffness Reduction Factors (SRFs) in the analysis of web-tapered I sections, a structural configuration known for its non-uniform geometry. Leveraging the advanced capabilities of the SABRE2-V2 software, the study investigates the direct load capacity of members and frames, focusing on the implications for structural efficiency and steel material utilization. The inclusion of fixed brace conditions at the midpoint of the beam member, with non-uniform bending, expands the applicability of INBA to complex configurations. The research validates the analytical methods through comparison with Finite Element Analysis (FEA) with four cases that includes different taper angle, achieving an average 98.6% consistency. The study unveils a characteristic S-shaped buckling pattern influenced by strategically placed braces, providing valuable insights into stability and performance optimization. Furthermore, INBA coupled with SRFs elucidates yielding patterns within the member, contributing to a comprehensive understanding of load-carrying behavior and potential failure mechanisms. The findings support the broader adoption of INBA for web-tapered I sections, offering engineers reliable tools for enhanced structural analysis and design. The paper concludes with implications for future research, suggesting exploration of varied taper angles, loading conditions, and material properties.