The building sector faces increasing pressure to reduce embodied carbon as operational emissions decline and life-cycle impacts of construction materials gain greater attention. Structural components such as roof purlins are widely used in industrial and commercial buildings and therefore represent an important opportunity for reducing material-related environmental burdens. This study presents a life-cycle environmental and economic assessment of alternative roof purlin systems manufactured from conventional and circular materials within a performance-based structural design framework.A life-cycle assessment and life-cycle cost analysis was conducted in accordance with EN 15804 + A2, covering Modules A1–A3 and C1–C4, with Module D benefits reported separately, using Australian life-cycle inventory datasets. Five purlin systems were evaluated, including recycled waste composite (RWP), cold-formed steel (CFS), timber (TP), fibre-reinforced polymer (FRP), and aluminium alloy (AAP). All systems were structurally optimised to achieve equivalent load-bearing capacity and serviceability over a 50-year service life, using 1 m2 of supported roof area as the functional unit. Results indicate that TP exhibits the lowest global warming potential (1.21 kg CO2-eq/m2), while RWP provides competitive environmental performance (6.96 kg CO2-eq/m2) and the lowest life-cycle cost (4.93 A$/m2). FRP and AAP exhibit the highest impacts under the primary Modules A–C comparison, although metallic systems show improved apparent performance when Module D benefits are reported separately. Integrated environmental–economic evaluation indicates that TP and RWP consistently outperform alternatives across multiple decision scenarios.The findings demonstrate that combining structural optimisation with appropriate material selection enables significant reductions in embodied carbon and cost and provides a decision-support framework for sustainable material selection under varying environmental and economic priorities.
To improve the mechanical reliability of thin-walled lithium disilicate (LD) veneers, this study developed a strengthening strategy that integrates vat photopolymerization (VP) with a two-step ion-exchange (IE) process. VP was employed to fabricate thin-walled LD structures, eliminating machining-induced damage, while a sequential K+/Rb+ IE process achieved both sufficient IE depth and compressive stress, overcoming their conventional trade-off. The two-step IE process increased the flexural strength of LD by 52.0% to 448.6 +/- 31.5 MPa and improved the fracture toughness by 80.4% to 2.64 +/- 0.10 MPa m1/2 . The significant enhancement in mechanical performance was mainly attributed to a 349% increase in compressive stress (CS), reaching 141.9 +/- 4.4 MPa. The atomic force microscope revealed that the ultrahigh CS was attributed to the volumetric expansion of an amorphous phase. Under scratching loads of 100 mN above the brittle-ductile transition threshold (similar to 70mN), the coefficient of friction of IE-processed LD increased by nearly 50%, indicating a transition in energy dissipation from brittle crack initiation to localized plastic deformation. Overall, the VP-fabricated LD, after undergoing the two-step IE processing, exhibits markedly enhanced strength and toughness. This improved mechanical performance effectively resists crack initiation and propagation caused by sharp contacts, thereby contributing to the superior long-term reliability of the LD veneers in the oral masticatory environment. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
The Monash-Peradeniya-Kodikara (MPK) framework interprets the volumetric behaviour of compacted unsaturated soils in the void ratio − moisture ratio − net stress (e-ew-p) space without requiring suction as an independent constitutive variable. Nevertheless, explicit knowledge of suction distributions within this volumetric space can provide additional insight into hydromechanical behaviour and facilitate comparison with conventional suction-based frameworks. This paper reconstructs continuous suction surfaces on and inside the Loading Wetting State Boundary Surface (LWSBS) within the MPK space by combining suction topology inferred from published experimental datasets with a constrained mathematical reconstruction methodology consistent with MPK principles. The reconstruction is divided into three regions relative to the Line of Optimums (LOO). At the wet side of the LOO, suction contours on the LWSBS are reconstructed using effective stress relationships and semilogarithmic compression relationships. At the dry side of the LOO, suction contours are reconstructed from Soil Water Characteristic Curves (SWCCs) extended towards the dry condition using cubic Bézier curves. Suction contours inside the LWSBS are reconstructed on constant net stress planes using fifth-order Bézier curves to generate smooth, continuous, and nonintersecting suction surfaces. Application to kaolin and Merri Creek soils produces suction profiles consistent with reported experimental trends, including suction reduction during constant moisture loading and a distinct transition in contour curvature across the LOO. The reconstructed suction surfaces preserve the fundamental structure of the MPK framework while providing the first explicit continuous hydraulic representation of suction within the MPK volumetric state space. They enable estimation of suction at intermediate soil states where direct measurements are unavailable, facilitate comparison with conventional suction-based interpretations, and establish a foundation for future constitutive, numerical, and coupled hydromechanical modelling within the MPK framework.
This study proposes a novel topological interlocking precast segmental column (TIPSC) based on a concrete-filled double steel tube (CFDST) configuration, aiming to address the limitations of conventional precast segmental columns (PSCs), including insufficient energy dissipation pathways and toe-dominated damage concentration. In the proposed system, the conventional sandwiched concrete core is replaced by a topological interlocking (TI) brick assembly, introducing distributed interfacial contact and frictional sliding as additional energy dissipation mechanisms. A detailed finite element model is developed based on a PSC benchmark experiment, and subsequently employed to compare the cyclic responses of TIPSC and PSC. Furthermore, parametric studies are conducted to investigate the effects of prestressing level, energy dissipation (ED) bar ratio, and TI configuration on the structural performance of TIPSC. Results show that, compared with the PSC benchmark, the TIPSC exhibits a fuller flag-shaped hysteresis, enhanced lateral strength, and increased activation of the frictional dissipation mechanism, while maintaining effective control of residual deformation. In addition, the TIPSC demonstrates delayed damage localisation and improved stiffness retention. Parametric analyses reveal that a moderate ED bar ratio combined with a higher prestressing level provides a balanced performance between self-centring capacity and energy dissipation, while an intermediate TI interlocking level is recommended to ensure effective frictional dissipation while maintaining sufficient kinematic compatibility. Specifically, through rational design of TI configuration and prestressing level, the demand for ED bars can be effectively reduced. These findings provide valuable design insights for the development of resilient segmental column systems.
Monopile-supported wind turbines (MWTs) are increasingly deployed in seismically active regions, where seismic loads can significantly affect their structural safety. Meanwhile, over a service life of 25-30 years, MWTs are continuously subjected to wind loads and 1P/3P loads. These lateral forces lead to the continuous evolution of soil properties, resulting in time-dependent seismic performance of MWTs. This study specifically focuses on onshore MWTs with the water table located below the pile tip, for which the effects of offshore environmental loads such as waves and currents are not considered. On this basis, a framework is proposed for evaluating the seismic response of MWTs after long-term operation, with comprehensive consideration of wind-structure-soil interaction. The framework can effectively characterize the long-term evolution of soil properties and analyze its influence mechanism on the seismic response. On this basis, the incremental dynamic analysis (IDA) method is employed to conduct a time-dependent seismic fragility analysis, and the seismic fragility curves under different operational histories are obtained. The results indicate that, with increasing operational duration, the probability of the wind turbine structure exceeding the serviceability limit state and the ultimate limit state increases significantly. Moreover, the influence mechanisms of factors such as wind characteristics and seismic characteristics on the structural seismic performance change significantly. Overall, the operational history of onshore MWTs has a pronounced degrading effect on their seismic performance.
