<p>Arc additive manufacturing (AM) technology offers high deposition efficiency, making it well-suited for the fabrication of large and complex structural components. However, the repeated thermal cycling can lead to stress accumulation, with excessive residual stress potentially causing cracking and structural failure. The improved inherent strain method has demonstrated effectiveness in rapidly predicting stress in arc AM structures. Nevertheless, the existing inherent strain application schemes lack consideration for complex structures with thermal and mechanical mutations. To address this limitation, this study establishes a finite element model for a 30° corner additive structure based on the thermo-elastoplastic (TEP) method and conducts experimental verification on the large-scale corner structure. By analyzing the influence of reheating effects in the corner region, multiple inherent strain application schemes were designed and evaluated. The scheme that applies the average inherent strain of the different trajectories showed good agreement with the TEP method in predicting X-direction stress. Compared with the TEP method, the average prediction error of X-stress in the linear center regions and corner regions of Path1 using the average inherent strain scheme is approximately 25 MPa and 46 MPa, significantly lower than the errors of 110 MPa and 130 MPa in the conventional inherent strain scheme. For Path2, the average corresponding prediction errors were about 53 MPa and 49 MPa. And the time cost of stress prediction using the inherent strain method is only 0.3% of that required by the TEP method. In the large 30° corner structure with a side length of 0.3 m, the errors of the stress at the midpoint and inflection point of the first trajectory relative to the experimental measurement are approximately 40 MPa and 65 MPa, respectively.</p>