L-flange bolted joints are extensively used in different industrial sectors, such as wind turbine towers, rocket stages, or pipelines. Typically, the design of these connections is based on analytical expressions derived from simplified beam models. However, the influence of specific factors such as curvature, adjacent bolts, or joint separation are not addressed within conventional approaches. Finite element models offer the advantage of comprehensively accounting for these effects and the interaction between different failure mechanisms. Nevertheless, their industrial implementation requires significant computational resources, in contrast to the use of analytical formulae. In this context, this paper proposes a new framework for designing optimized L-flange bolted connections, based on general closed-form expressions that rely on validated numerical results. Three expressions, each one related to a particular failure mechanism, are derived from parametric simulations varying the most influencing parameters in the structural behavior. The generated equations can be easily implemented to guide the design process towards an optimal configuration, taking advantage of beneficial effects not addressed within classical approaches. A closer prediction of the actual load capacity of the joint can be obtained, providing a tool that allows engineers to make more reliable and economical designs.