Abstract:With increasing societal awareness of environmental protection, the production process of traditional cement has become an area in urgent need of innovation because of its significant carbon emission contributions and generation of industrial solid waste. As a new type of low-carbon cementitious material, geopolymers not only consume less energy and produce fewer carbon emissions but also effectively allow for the reutilization of industrial solid waste, demonstrating its immense potential for further development. However, the inherent brittleness and poor crack resistance of geopolymers limit their structural applications. The crack resistance of concrete can be significantly improved by utilizing self-stressing structures to generate internal stress or by taking prestressed concrete with its unique manufacturing methods. Furthermore, incorporating admixtures to enhance the material''s inherent crack resistance presents another viable strategy. Owing to their excellent mechanical properties, carbon nanotube fibers offer new possibilities for addressing these limitations of geopolymers. In this review, the use of carbon nanotubes (CNTs) to enhance geopolymer performance is investigated. A comprehensive analysis of existing studies reveals that the incorporation of CNTs significantly improves the crack resistance and mitigates the brittleness of geopolymers. Optimal overall performance is frequently reported at CNT dosages between 0.12 wt.% and 0.14 wt.%. These findings provide a theoretical foundation for the practical engineering of CNT-reinforced geopolymers and contribute to the development of sustainable construction materials.

Abstract:Nanhai Avenue, located in Nanchong, Sichuan, is a major urban road built along mountains. The project involves the comprehensive treatment of a high and steep slope, which is characterized by elevated height, complex geological conditions, and a large volume of landslide mass. Moreover, the newly constructed bridge structure that is present adjacent to the slope poses strict requirements for slope deformation control. Based on the high-slope project on Nanhai Avenue in Nanchong, in this paper, a finite element model is constructed using Plaxis software to study support measures for high slopes. The results reveal that in slope protection, anti-slide piles play a crucial role in bearing the majority of the landslide force, and after prestress is applied, frame anchor cables can significantly share the landslide force, reducing the displacement and internal force of anti-slide pile shafts. Frame anchor cables transfer the landslide force to deep anchored soil layers, significantly reducing the deformation of soil behind piles, which plays a key role in controlling deformation of the bridge adjacent to the slope and ensuring the safety of the bridge structure. It is anticipated that the results of this study will provide reference data for similar projects in the future.

Abstract:While the theories and methods for designing the steel sections of wind turbine towers are relatively well established, the design of concrete tower sections, particularly the methodologies for concrete fatigue design, varies across different codes and standards. These methodologies often involve complex calculation parameters and formulas, which can be prone to misinterpretation and misapplication. This paper primarily traces the evolution of provisions in the fib Model Code and the Eurocode, offering recommendations for determining concrete mechanical properties, structural analysis methods, and fatigue design approaches. Furthermore, a concrete fatigue calculation example is presented based on an engineering case study. This example illustrates key considerations for selecting critical parameters and applying the relevant calculation formulas. The aim is to provide a more in-depth understanding and improve the application of concrete fatigue design principles.

Abstract:随着我国城市化进程的加速推进,城市高架桥梁建设规模持续扩大,传统落地式支模架体系在高墩、大跨预应力盖梁施工中面临严峻挑战。该类体系普遍存在占地面积大、材料消耗多、施工效率低等问题,特别是在城市中心区域施工时,对周边交通造成严重干扰,难以满足现代城市桥梁建设的要求。本文系统研究的高墩盖梁轻量化不落地支模架体系,通过采用ASA高分子增强型合金模板和不落地型钢支架等新型材料与结构形式,实现了支模系统的轻量化、装配化与绿色化。该体系创新性地解决了传统施工方式中的多项技术难题,显著降低了施工过程中的碳排放,提高了材料周转利用率,体现了绿色建造理念。工程实践表明,该体系在温州温瑞大道、杭州时代大道、宁波九龙大道等典型项目中取得了显著成效。实践表明,该体系在施工效率、成本控制、资源节约及环境影响等方面均表现出显著优势,具备良好的推广应用价值。

Abstract:China has entered a period of large-scale bridge maintenance, and long-span cable-stayed bridges in service for more than 15 years are frequently facing issues such as water seepage at anchorages, excessive humidity, and corrosion of steel components. Via traditional sealing and monitoring methods, it is difficult to detect hidden hazards in concealed areas in a timely manner. In this paper, an anchorage end protection system that integrates visual monitoring and active humidity control while accounting for sealing conditions is proposed. Using actual cases such as the Jintang Bridge and Taoyaomen Bridge from the Zhoushan Island Link Project, the shortcomings of traditional maintenance measures and the causes of defects are analyzed. Experimental and onsite validation demonstrate that this system effectively delays corrosion, enhances detectability, and improves maintenance efficiency, providing an engineering reference for the full-lifecycle management of large-span cable-stayed bridges.