Round-Robin Modelling of the Load-bearing Capacity of Slender Columns by Using Classical and Advanced Non-linear Numerical and Analytical Prediction Tools

Abstract

Non-linear finite element analyses have intrinsic model and user factors that influence the results of the analyses. However, non-linear finite element analysis can provide a tool to assess safety using realistic descriptions of material behaviour with actual material properties. A realistic estimation of the existing safety and capacity of slender column elements can be achieved by means of "true" material properties. Nevertheless, it seems that for some structural components, such as slender columns, non-linear finite element analyses can, due to its complexity and its various setting parameters, cause the risk of overestimating the real performance of analysed components or systems. Hence, an invited expert group has carried out an investigation into the experimental testing and the prediction of the bearing capacity of slender columns by performing independent non-linear finite element analyses in order to determine the practical applicability, and its inconsistencies, with respect to the stability failure of slender columns. This work aims the characterization of modelling uncertainties, concerning the prediction of slender columns stability when forecasted by non-linear finite element analysis.

Probabilistic and Semi-Probabilistic Analysis of Slender Columns Frequently Used in Structural Engineering

“…The concrete material used to construct the first series of slender columns is C45/55 while the steel used is BST 500B. In the first series, 6 columns (see also [4]) were tested. Figure 5 shows the cross-sectional dimensions and layout of the tested columns while Table 1 lists the parameters used in the calculation according to different codes.…”

“…Based on the results from the experimental investigations, see Figure 6, and the previously discussed model uncertainty factors, the following design values of the resistance can be determined according to [4]:…”

“…is the m-dimensional joint probability density function (PDF) of the m basic variables X i . The structural reliability is quantified through the reliability index β, which can be generally expressed and calculated-assuming a normal distribution for g(x)-through Equation (4).…”

“…The general approach described above can be implemented by applying various formats of different intricacies together with their corresponding efficiencies. Recent experimental studies for slender reinforced concrete columns [3] have indicated that the classical design approaches for distinguished N-M combinations are too conservative and so cannot meet the reliability level that is required in current design standards and the desired level of structural safety required in modern societies [4][5][6]. Simultaneously, due to the rapidly developing computational technologies and formats, more sophisticated numerical probabilistic simulations and non-linear calculation formats are becoming more important and finding their way into engineering practice [7].…”

“…A key aspect in deciding on the appropriate configuration of non-linear calculations is the consideration of possible variations in complex and interacting input parameters. To that end, Strauss et al [4] indicated the reliability deficiencies in the above-mentioned design situation of slender columns by assessing to what extent a group of peer institutions can capture this deficiency with independent non-linear numerical analyses. Furthermore, this study allowed a quantification of the modeling and calculation uncertainties [15].…”