Slender structures are employed as key elements in various engineering applications. Their utilisation is further driven by the introduction of new materials that allow the design of highly optimised shapes. Geometrical nonlinearities drive the mechanical response of these structures, while their material may behave either elastically or inelastically. Furthermore, imperfections can significantly influence their response and safety. As such, the development of robust, efficient, and accurate numerical methods for analysing slender structures remains a fundamental research area in computational mechanics. In light of these considerations, this mini-symposium aims to bring together researchers from around the world who are advancing methodologies for the geometrically nonlinear analysis of structures in civil, mechanical, marine, aerospace, and biomedical engineering. Contributions may involve: - Discretisation methods as weak and strong formulations (i.e., Finite Element Method, Virtual Element Method, Boundary Element Method, Galerkin formulations, Isogeometric Analysis). -Advanced methods and algorithms to recover the nonlinear behaviour of lightweight structures. -Reduced-order, surrogate, machine learning, and data-driven models. -Geometrically nonlinear phenomena in coupled problems. -Multi-level and multi-scale analysis of geometrically nonlinear structures. -Numerical methods for the imperfection sensitivity analysis and reliable safety assessment of slender structures. -Optimisation of lightweight structures in nonlinear range. -Enhanced structural 3D beam and shell models undergoing large deformations.