Figure 12.
The diagram shows a reinforced element inside surrounding material with a moment M applied to it. The equation M, M b plus M ax, divides the moment into bending and axial parts. The bending part shows two curved members with labels M b, t and M b, l. The axial part shows two straight members with labels V t and V l. A spiral spring labelled K R shows rotational stiffness. A paired spring labelled K R, axial connects to two larger spring models. One larger model shows vertical stiffness with labels K V, t and K V, l. The other larger model shows bending rotational stiffness with labels K R, b, t and K R, b, l. Dashed lines connect the simple stiffness symbols to the larger spring models.Illustration of the two moment resisting mechanisms for an idealised 2 × 1 pile group layout; simple spring models employed to reproduce each mechanism (Sakellariadis et al., 2026). Decomposition of total rocking stiffness, in rocking stiffness stemming from the axial loading of the piles, , and the rocking stiffness corresponding to the bending stiffness of the piles, . Further decomposition of to vertical strings for compression and tension, and decomposition of to rotational springs in each pile head (function of the axial loading of each pile)