This study presents a computational approach on the load-carrying capacity of steel pipe beams with reinforced flange joints under boulder impact. First, the computational method is validated by comparing with the experimental results. Second, the steel pipe beams with reinforced flange joints under impact load were investigated by comparing with the difference between the impact position. Herein, the three kinds of reinforced flange joint models are proposed as Type1: increasing the number of bolts only at the tensile side of joint, Tyep2: setting a steel covered with a plate at the tensile side of joints and Type3: increasing the number of bolts evenly at whole joint. Therefore, the flange joints reinforced by a steel covered with a plate at the tensile side was the most effective measure for a boulder impact.