When reinforcement in concrete corrodes, splitting stresses around corroded bars may lead to cover cracking and even cover spalling, affecting the anchorage. The aim of this study was to validate an existing one-dimensional (1D) analysis for anchorage capacity, and to show how it can be applied in assessment of existing bridges. The 1D analysis was validated through comparisons to experiments and detailed 30 finite element analyses. The methodology is exemplified in assessment of two bridges built in the 1960s. The bridges exhibit systematic damage in the form of spalled concrete on the bottom side of the main beams at cast joints where large amounts of reinforcement are spliced. The anchorage length needed to anchor the yield force was calculated from the bond-slip response, using the one-dimensional bond-slip differential equation. The model proved to be easy to use in practical design work. Furthermore, the bridges could be shown to have sufficient capacity, and costly strengthening could be avoided. This work clearly demonstrates the potential to certify sufficient load-carrying capacity of corroded reinforced concrete structures through improved models.