This paper presents a new approach to the structural availability quantification of a slender beam element affected by external random loads with a special focus on yield strength. The proposed method introduces the concept of structural availability, which is intrinsically identical to the concept of operational availability in system reliability engineering. Structural availability is formulated with structural failure and repair models. The failure model is determined based on failure probability and the Poisson approximation. In applying the structural availability method to design, it is possible to quantitatively measure features related to the operation and maintenance of structures and to identify cost-effective design options. To understand feasibility levels of structural availability, two cases based on actual design data are examined using the proposed method. The case study results illustrate not only processes of quantifying the structural availability of a beam element but also the cost-effectiveness evaluations on specific design options.