In this study, an irregular lattice model for geometrically nonlinear analysis of structures is proposed. A conventional lattice element formulation, based on the rigid-body-spring concept, is extended to reflect geometric nonlinearity under large displacements. The large rotational behavior of each lattice cell is considered. Along with general derivation of the new lattice element formulation, an explicit solution scheme is implemented for the dynamic analysis of structures. Examples are presented to demonstrate capabilities of the proposed method for solving geometrically nonlinear problems of elastic solids. Benchmark comparisons are made with finite element solutions for both dynamic and quasi-static loading cases. (C) 2020 Elsevier Ltd. All rights reserved.