In this paper, a probabilistic framework is proposed to estimate the reliability level of existing structural steel design codes, identify the underperforming safety cases and calibrate partial safety factors. The approach simulates various design scenarios and estimates the reliability index for each using simplified equations. This allows for the analysis of numerous random structural components under different load combinations. The framework identifies critical load combinations from a reliability perspective and pinpoints key factors contributing to reduced safety levels. Load and resistance factors are then recalibrated within these critical combinations to achieve the required safety standards. The method is applied to the National Building Code of Iran, which directly adopts load and resistance factors from North American standards ASCE/SEI 7 and AISC-360, to assess its reliability and recalibrate partial safety factors based on local uncertainties and statistical parameters of resistance and loads. The proposed methodology is simple and straightforward, making it easily applicable to other international and national structural steel design codes
