A Simplified Approach to Creep Buckling of Structures Under Varying Loads

A critical strain approach to the prediction of creep buckling time in structures under varying loads is investigated and its relationship with the conventional linear cumulative damage (life-fraction) approach is established under condition of constant temperature. The latter approach is shown to be inconsistent in some special cases and may result in overprediction or underprediction of creep buckling time depending on whether the loads are monotonically increasing or decreasing. Numerical results obtained with the present approach are compared with incremental solutions for columns, and with recently available theoretical and experimental results of cylindrical shells under axial compression. These comparisons indicate that the critical strain approach is suitable for use in design analysis. Further investigations are needed to assess the effect of varying temperature, which is excluded in the numerical examples because no test results are available for comparison.