PSI - Issue 78

Marta Bertassi et al. / Procedia Structural Integrity 78 (2026) 1521–1528

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Fig. 4 presents two complementary perspectives on the comparison between code-based NLKA and NLTHA results. In Fig. 4a, the green region indicates cases where the code-based procedure overestimates displacement demand, while the red region highlights underestimations relative to NLTHA results. Fig. 4b categorizes the outcomes into four quadrants: (1) exceedance of the considered limit state according to the codes but not to NLTHAs; (2) exceedance by both methods; (3) no exceedance by either; and (4) exceedance in the NLTHA but not according to the codes. The graphs also show displacement limits for the three considered overburden loads (represented as vertical solid lines) calculated analytically using formulas provided by Tomassetti et al . (2018).

Fig. 4. Interpretation of displacement demand predictions: (a) overestimation (green) and underestimation (red) by the code-based NLKA with respect to the NLTHA outcomes. (b) Classification of outcomes based on collapse predictions from NLKA and NLTHA across four quadrants.

Fig. 5. Comparison between NLTHA and NLKA predictions by NTC 2018 and FprEN 1998: (a) wall W1 ( h = 3 m , t = 0.12 m); and (b) wall W2 ( h = 3 m , t = 0.24 m).