Editorial

Regular papers

The first paper, ‘Structural performance assessment of stochastic fractal grid-shell structures using different recursive generation algorithms’ by Yaser Shahbazi and Mahsa Abdkarimi, investigates the structural behaviour of fractal grid-shell systems generated through different recursive strategies. Fractal patterns are developed using three approaches: a fully stochastic method, a deterministic method with constant ratios and a deterministic method with independent ratios at each iteration. A conventional square grid-shell is also considered for comparison. The generated planar configurations are mapped onto spherical, hyperboloid and hyperbolic surfaces. Using both single and multi-objective optimisation, with structural mass and maximum deflection as the principal quantities to be minimised, the study shows that fractal grid-shells, particularly those generated using independent ratios, can achieve efficient lightweight designs under both symmetric and asymmetric loading. Comparisons with conventional grids confirm improvements in structural mass and in the distribution of stresses and deflections.

The second paper, ‘Mechanical performance of SLO joints for single-layer reticulated shells under bending shear and axial eccentric loading conditions’ by Dabin Yang, Zhenhang Wei, Ren Zhang, Xuesong Tian and Baochen Zhu, examines the behaviour of SLO joints with separated joint bodies under combined loading conditions. A finite element model is validated against experimental results, and a parametric study is carried out to investigate the influence of end plate thickness, bolt size, axial eccentricity and lever arm. The results show that axial eccentricity has limited influence on initial rotational stiffness but a significant effect on ultimate bending moment. Under bending shear, end plate thickness has a limited effect, while increases in bolt size and lever arm lead to higher stiffness and bending capacity. Based on these findings, the authors propose calculation formulae for initial rotational stiffness and ultimate bending moment, providing practical guidance for the design of such joints.

The third paper, ‘Research on the stiffness of the Improved Bolt-Column (IBC) joint subjected to eccentric and combined loads’ by Yuxing Fei, Hanyang Li, Annan Wang, Junjie Fang and Huijun Li, investigates a modified semi-rigid connection designed to enhance bending performance. The study examines failure modes and mechanical response under eccentric and combined axial and bending loading. Moment-rotation and axial load-displacement relationships are obtained for different plate thicknesses and eccentricities. The results show that both parameters increase initial stiffness and ultimate moment capacity, and a critical eccentricity of 200 mm is identified beyond which the behaviour approaches that of pure bending. Under combined loading, axial tension reduces both stiffness and capacity, while axial compression leads to a more complex response. Predictive relationships are developed to quantify the influence of eccentricity and axial force on bending capacity, contributing to improved understanding and design of semi-rigid joints.

Continuing education article

The final paper, ‘Grasshopper formulation for the snub dodecahedron and the pentagonal hexecontahedron’ by Jaime Sanchez-Alvarez, is presented as a Continuing Education Article. It demonstrates how the scripting capabilities of Grasshopper within Rhinoceros can be used to generate two complex semi-regular polyhedra: the snub dodecahedron and its dual, the pentagonal hexecontahedron. Using a numerical method based on the regular icosahedron, the paper outlines the geometric construction process and its implementation in a computational environment. The study highlights the challenges associated with data structure organisation and algorithm development in parametric modelling, and provides a practical tool that can support further applications of complex polyhedral geometries in architectural and structural design.