This issue of Structures and Buildings consists of six technical papers. Research investigations concerning curved continuous beam bridges, concrete chimneys, railway tracks, ultra-high performance concrete beams, tuned mass dampers and geopolymer concrete are covered.
The first paper by Chen et al. (2025) discusses a mechanical parameter optimisation framework tailored for bridge seismic isolation bearings. A finite-element model of a three-span curved beam bridge was developed to assess the seismic vulnerability curves for both the bridge components and the entire system. The results demonstrate that the pre-yield stiffness, post-yield stiffness and yield force of the lead-rubber bearings influenced the seismic response of the curved continuous beam bridge. By using optimised parameters, the damage probability of the bridge pier was minimised, improving the overall seismic performance of the bridge.
In the second paper by Rahman et al. (2025), the authors presented an analysis of concrete chimneys under random vortex shedding in which aeroelastic interaction was duly considered. The reliability analysis was determined using Vanmarcke’s double barrier cross-ing analysis. In addition, the effects of important parameters such as the turbulence intensity, lift coefficient, correlation length, Strouhal number and total damping on the responses and reliability estimates of three chimneys were investigated. The authors concluded that international wind codes underestimated the responses of taller chimneys compared with those predicted by direct spectral analysis.
The following paper (Gama et al., 2025) includes a theoretical and experimental analysis of the mechanical behaviour of a railway track. A numerical model was formulated regarding the rail as a continuous elastically supported beam, following the Winkler foundation concept. According to the authors, the theoretical and experimental results presented a good correlation. Finally, the authors concluded that the developed procedure, which correlates the shear forces measured on the rail web with the vertical geometric regularity of the track, proved to be a promising method for monitoring the integrity of the railway superstructure, notable for its simplicity of measurement and low cost.
In the fourth paper, the investigation developed by Melchiors et al. (2025) concerned an experimental parametric analysis and numerical simulation of ultra-high-performance concrete (UHPC) beams with microfibers. A numerical model was developed to assess the effects of the type and contents of different microfibers on the mechanical performance of reinforced concrete beams. The small-scale test results indicated an improvement in the tensile behaviour of the UHPC and a negligible influence of fibre content on the compressive response. Finally, the authors stated that the fibres increased the elastic performance of the beams but had little effect on their plastic behaviour (ULS). Except for the cases where the incorporation of 2% steel fibres was used, the mechanical capacities of the UHPC beams were reduced.
In the fifth paper, the investigation developed by Allani and Ali (2025) concerned a design optimisation and performance evaluation of single and multiple-tuned mass dampers (MTMDs) controlling multiple degrees of freedom structures. The numerical criterion was employed to optimise the parameters of each TMD, including stiffness and damping. The performance of the optimised MTMDs in mitigating the structural response under seismic excitation was evaluated through the application of real earthquake records. According to the authors, the results show that numerical optimisation criteria outperform or match the performance of existing methods in reducing both top-floor displacements and RMS displacements across several earthquake records, with a clear superiority in specific cases.
The last paper by Ghafoor et al. (2025) looked at the impact of sodium hydroxide (NaOH) concentration on the behaviour of fly ash-slag-based blended ambient-cured geopolymer concrete (GPC). The increase in sodium hydroxide concentration from 8 molar to 16 molar resulted in a continuous decrease in the workability of GPC, which was solved by increasing the water-reducing admixture. However, the increase in sodium hydroxide concentration positively influences the strength development of fly ash–slag-based ambient-cured GPC. Finally, the authors concluded that the comparison of life-cycle assessment indicated that GPC is a sustainable alternative that offers a 49% reduction in greenhouse gas emissions compared to ordinary Portland cement-based concrete.
The Editor would like to thank all the authors, reviewers and readers, and discussions on any of these papers are welcome.
