Development of the effective length method for single-story frame analysis

Introduction. The current steel structure standards (SP 16.13330.2017) propose two methods that are used to solve the stability problem of frame structures: unified nonlinear systems and the effective length method. The former is not widely used, making the latter the primary approach for calculations. However, the current code contains only a few calculation schemes for determining the effective length factor, which does not fully address current engineering needs. This limitation makes it difficult to find quick solutions and necessitates the use of numerical analysis. Furthermore, the effective length method provides reliable results, but it takes more time to perform the calculations. This paper proposes a pathway for developing the effective length method and provides specific examples of problem-solving. This approach addresses a significant number of typical cases for single-story buildings and provides the necessary theory for solving multi-story cases. Aim. This article aims to develop the effective length method. Materials and methods. Development of effective length factor equations through modification of the shift method and comparison of analytical solutions in the LIRA-SAPR Software complex. Results. The analytical work presented here offers a set of equations that support the development of the effective length method. These solutions complement document SP 16.13330.2017. The numerical analysis results confirm the obtained analytical solutions. Conclusions. There is potential to expand the code of practice for steel structures, SP 16.13330.2017.