<p>Lattice-shaped diaphragm wall (LSDW) foundations are an innovative solution for cross-sea bridges, yet their behavior and bending moment characteristics under horizontal cyclic loading remain insufficiently studied. Building upon our previous research on the cyclic lateral response of LSDWs in soft soil (Wu et al. Front Struct Civ Eng 18:1815–1828, 2024a), this study further investigates the deformation and bending moment characteristics of LSDW foundations through laboratory model tests on single-cell and two-cell configurations. The importance of this investigation lies in its novel measurement of bending moments for both inner and outer walls using a two-layer wall structure and integrated instrumentation, providing critical insights into differential stress distribution under cyclic loading. Results demonstrate that both foundation types exhibit rapid initial lateral displacement followed by stabilization, with the two-cell design showing reduced displacement due to enhanced rigidity and greater wall–soil contact area. Cyclic secant stiffness analysis reveals stiffness degradation with increasing load amplitude but progressive stiffening with loading cycles, with the two-cell configuration maintaining higher baseline stiffness. Bending moment measurements indicate peak moments at approximately one-third of the wall height, with significant accumulation within the first 100–200 cycles, underscoring the need for targeted reinforcement. These findings enhance the understanding of LSDW mechanical behavior, offering a scientific basis for optimizing their design and ensuring long-term stability in cross-sea bridge applications.</p>