With China’s government facilitating railway projects, more railway bridges (RBs) are gradually built in complex and difficult mountainous areas (CDMAs). The construction activities of RB in CMDAs are facing formidable challenges in terms of the natural environment, technology, and organization management, which are hardly solved by traditional bridge design and construction techniques. Therefore, there is an urgent need for technology innovation (TI). Studies on the management of RB-TI in CMDAs are limited. As such, this study aims to offer an effective modular management approach to RB-TI in CMDAs. A system of demand and obstacle factors for RB-TI in CMDAs was identified firstly based on the literature review and the grounded theory, including seven intermediate codings and 29 initial codings. Then these factors were regarded as the system requirements for modular decomposition, to establish a “cut-to-fit” modular management approach to RB-TI in CMDAs. A case (i.e., the LD bridge project of the CZ railway) was selected to demonstrate and validate the developed approach. The results show that the proposed approach can be applied to manage RB-TI in CMDAs. The innovation of this study lies in the integration of grounded theory and modular theory and provides modular management ideas and measures for bridge engineering technology innovation. Findings from this study enrich the knowledge body of RB-TI and guide innovation subjects in the practical management of RB-TI in CMDAs.

Despite the attractive merits of high-capacity strands, the application in bridge girders is limited due to concerns, including concrete cracking, excessive stress, and cambers. An efficient and defect-free production is the first step to wide application. The objective of this research was to alleviate the production concerns of prestressed concrete bridge girders using high-capacity strands. A gigantic prestressed concrete box girder using 18-mm strands was produced; its entire fabrication process (from strand stressing to detension) was introduced. Sixteen temperature gauges were embedded in the girder to monitor the hydration of the large volume of concrete and the adjacent environmental temperature. Moreover, displacement transducers were used to measure the camber at detension; load cells were installed to monitor the variations of the prestressing strand tensile forces during fabrication. Monitoring and analysis showed that the timing of the detension is determined by the hydration of the concrete, the compressive strength of the concrete, and its modulus of elasticity or age. Since the tensile forces in strands are affected by the concrete’s internal temperature, the detension is conducted after the concrete temperature falls back (close to its initial value); otherwise, unfavorable and considerable prestress losses are caused. Finally, a 4-d detension was suggested since the hydration was not a concern at the time; the predicted prestress loss and camber were acceptable and the concrete material properties at 4 d satisfied the requirements.

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Reactive powder concrete(RPC) is a kind of ultra high performance concrete material, which has ultra high compressive strength and durability as well as good tensile property, elastic modulus, energy absorption and ductility. All these properties make it to be a better choice for the construction of bridges, buildings, military architectures, nuclear structures and the buildings bearing severe environment. The good tensile property, durability and ductility of RPC depend on the steel fibres mixed in the concrete. The bridge effect of steel fibres provides high tensile strength and crack resistant property. The tensile constitutive model of RPC differs from the normal concrete. This study tried to obtain the tensile constitutive model of RPC based on the flexural experiments of RPC prism. On the basis of test results, the tensile constitutive model of RPC is given in this study.