Simplified criteria and economic design for king piles in combined steel pile walls according to Eurocode 3, part 1-1

The steady growth in world trade leads to a demand for more port and harbour facilities. One of the most common forms of construction for deep-water harbour quays is the combined steel pile wall. It consists of up to 45 m long H-section king piles plus Z-section intermediate sheet pile infill elements. The intermediate elements and the quay both transfer all forces to the king piles, which as a result are loaded with (bi)axial bending and axial force, so their stability must be checked. Up to now the effect of the soil surrounding the piles was used just in terms of best practice - buckling about the weak axis and lateral torsional buckling were neglected completely. Considering these stability phenomena in design without taking the soil into account would lead to a very conservative approach. As verification of lateral torsional buckling according to EN 1993-1-1 (EC3-1-1) becomes relevant when the embedment is neglected, a more refined analysis has been developed.
This article presents simplified criteria that quickly exclude stability phenomena (flexural buckling about the weak axis and lateral torsional buckling) while taking into account the effects of the soil. For the cases in which the criteria are not fulfilled, the article presents economic solutions that consider the embedment of the king piles in the soil in the design for stability.