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Bacterial cellulose (BC) has been recognized as an ideal supporter owning to its abundant hydroxyl groups on the surface. In this work, Keggin-type phosphotungstic acid (H3PW12O40, PWA) is self-anchored on the three-dimensional network of BC by a simple diffusion method at room-temperature. BC fibers can protect the well-dispersed PWA with high transparency, high mechanical strength, and high stability. When PWA/BC serves as a photochromic material, the coloration time and bleaching time are only 3 min and 30 min respectively. After 6 cycles, the photochromic ability of the PWA/BC composite film almost unchanged. At the same time, we convert the coloration and bleaching degree into quantitative data including a color difference calculation of ΔE2000 and the remaining degree of color (RC%). Within the BC system, PWA exhibits a special linear relationship between RC% and bleaching time (0–30 min). The processes of PWA/BC reduction (W6+→W5+) and oxidation (W5+→W6+) are analysed by photo-electrochromic, XPS and ESR characterizations. The revealed excellent photochromic properties of soft PWA/BC films highlight their potential as the photoresponsive materials.

[Display omitted] Self-anchored PWA on the three-dimensional network of BC with flexible, quick-response and stable cycling performance for photochromic application. • PWA self-anchored through the bridging oxygen interaction with –OH groups of BC. • Quick-response of the coloration time (3 min) and bleaching time (30 min). • A charge transfer bridge of PWA/BC greatly improves the mechanical properties. • 6 cycles test confirms the stable performance with retention rate up to 99.6%. Bacterial cellulose (BC) has been recognized as an ideal supporter owning to its abundant hydroxyl groups on the surface. In this work, Keggin-type phosphotungstic acid (H 3 PW 12 O 40 , PWA) is self-anchored on the three-dimensional network of BC by a simple diffusion method at room-temperature. BC fibers can protect the well-dispersed PWA with high transparency, high mechanical strength, and high stability. When PWA/BC serves as a photochromic material, the coloration time and bleaching time are only 3 min and 30 min respectively. After 6 cycles, the photochromic ability of the PWA/BC composite film almost unchanged. At the same time, we convert the coloration and bleaching degree into quantitative data including a color difference calculation of ΔE 2000 and the remaining degree of color (RC%). Within the BC system, PWA exhibits a special linear relationship between RC% and bleaching time (0–30 min). The processes of PWA/BC reduction (W6+→W5+) and oxidation (W5+→W6+) are analysed by photo-electrochromic, XPS and ESR characterizations. The revealed excellent photochromic properties of soft PWA/BC films highlight their potential as the photoresponsive materials. [ABSTRACT FROM AUTHOR]

Prestressed membrane roofs have been designed since the invention of prestressed concrete. They are described in the basic books written by pioneers of prestressed concrete. For illustration, four architecturally most successful roofs are discussed. The authors emphasize that the prestressed membrane roofs are still modern, structurally efficient, and architecturally interesting. If they are assembled of precast members, they can be erected without scaffolding. Recently, the authors have studied different membrane structures from the point of view of their architectural and structural arrangement, process of erection, and static and dynamic behavior. In-depth studies were carried out for membranes of simple curvature situated above the whole or portion of the rectangle area and self-anchored membranes supported by arches or shells. Also self-anchored suspension membranes situated above circular or elliptical plans, hypar membranes, and membranes of a free form that are suspended on arches or suspension cables were analyzed. [ABSTRACT FROM AUTHOR]

Geometrical nonlinearity of self-anchored cable-stayed suspension bridge was studied. The influences of shrinkage and creep of concrete, rise span ratio and girder camber on system were discussed. A self-anchored cable-stayed suspension bridge with main span of 800 m was analyzed with linear theory, two-order linear theory and nonlinear theory. The moment and displacement of girder, pylon under different rise span ratio and girder camber stages with live load were gotten. According to the results of analyses, the live load of a self-anchored cable-stayed suspension bridge with main span of 800 m can be analyzed with two-order linear theory and the error is less than 6%. The shrinkage and creep of concrete greatly affect the structure. And the system stiffness is superior to that of suspension bridge. As the rise span ratio becomes larger, the axial force and stiffness of main cable and girder are smaller. The system stiffness increases if main girder camber is set. [ABSTRACT FROM AUTHOR]

A self-anchored cable-stayed-suspension bridge is a new type of structure bridge. There are some technical problems, such as wind resisting stability and so on. Detailed study is done on the influence of pile foundation rigidity, wind load of cables, cables segmentation, initial and additional attack angle on main girder and pylon displacement of the Jinzhou Gulf Bridge under the static wind condition by calculating the aerostatic response of cable supported bridge. The results show that the additional attack angle has little influence on the displacement induced by static wind of the bridge. If the pile foundation rigidity effect is not taken into account, the lateral displacement will be severely underestimated. The lateral displacement due to the wind load of cables is almost 20 percent of that of the total wind load. [ABSTRACT FROM AUTHOR]

The limit span of self-anchored cable-stayed suspension bridge is deduced. The relations among the geometrical parameters, loads and material characteristics are also analyzed. Based on the material strength and commonly used materials, the limit spans of self-anchored cable-stayed suspension bridges with concrete girder or steel girder under vertical static load are discussed in detail. The corresponding upper limit spans and the effect of the factors on the span are given. The results indicate that increasing rise-span ratio, height-span ratio and cable-stayed segment length or reducing the second dead load could increase the cooperation system span. [ABSTRACT FROM AUTHOR]

The limit span of self-anchored cable-stayed suspension bridge is deduced. The relations among the geometrical parameters, the loads and the material characteristics are also analyzed. Based on the material strength -and the commonly used materials, the limit spans of self-anchored cable-stayed suspension, bridges with concrete girder or steel girder under vertical static load are discussed in detail. The corresponding upper limit spans and the influence of the factors on the span are given. The results indicate that increasing rise-span ratio, height-span ratio, cable-stayed segment length or reducing the second dead load can increase the cooperation system span. [ABSTRACT FROM AUTHOR]

To mitigate the seismic response of self-anchored suspension bridges, equations of motion governing the coupled system of bridge-magneto-rheological (MR) dampers subject to seismic excitation are formulated by employing the phenomenological model of MR dampers. A corresponding computer program is developed and employed for studying the seismic response control of a self-anchored suspension bridge with a main span of 350 m. The effect of variable current and number of dampers on seismic response control is investigated. The numerical results indicate the longitudinal displacement of the tower top and bridge girder decrease with the increase in input current and number of MR dampers attached longitudinally at the tower-girder connections, and the internal forces of the tower are effectively attenuated as well. It appears that small electronic current (0.5 A in this study) may sufficiently attenuate the seismic responses for practical engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: For self-anchored suspension bridges, stiffening girders or trusses should be erected prior to the air-spinning of the main cables. Since hangers are installed between pre-constructed stiffening trusses and main cables, tensioning processes are necessary for hanger installation in the case of a self-anchored suspension bridge. Since hanger tension variations in construction are quite dependent on the constructional plan adopted, the jacking force and probable maximum tension should be predicted and compared in the constructional design state so as to determine the most feasible and effective plan among the possible options. This is generally done by the use of a so-called geometrically nonlinear construction step analysis. A finite element (FE) analysis procedure, which utilizes elastic catenary cable element formulation for controlling the length of the cable members, is proposed for the development of a hanger installation plan, in particular for the self-anchored Yongjong Bridge. As a pre-requisite to a rigorous backward/forward construction step analysis, an unbalanced load-free FE model was established following a nonlinear shape-finding analysis procedure. Based on a series of comparative studies, an installing plan, which utilizes the synchronized jacking of a maximum of 80 strand jacks with the combination of a divided tensioning technique, is proposed and its successful application to the construction of the Yongjong Bridge is described. [Copyright &y& Elsevier]

A non-linear shape-finding analysis is proposed for a self-anchored suspension bridge, the Yongjong Grand Bridge, the main cable of which is three-dimensional in shape. The proposed procedure consists of two successive steps of non-linear analysis. The first step focuses on the cable-only system and the second on the total bridge system. A trial profile of a three-dimensional main cable was calculated based on the conventional method utilizing a simplified force equilibrium at each node of the main cable. The non-linear analysis is then repeated for this cable-only system until the profile converges to the target configuration that satisfies the vertical design sag at the mid-point of the main span. Even when the best efforts were made to determine the configuration of the cable-only system, the initial deformation of the stiffening truss is not avoidable due to the huge axial force that originates from the main cable. Therefore, the initial frame forces are predicted and included in calculating the unbalance loads for the non-linear analysis of the total bridge system so as to prevent dead load deformation. The possible differences between the conventional and the proposed method are examined through numerical applications. [Copyright &y& Elsevier]

CFRP cables are promising to be utilized in bridge engineering, but their effective anchorage remains a challenge for engineers. To solve this problem, novel self-anchored CFRP cables with different anchorage configurations were designed and tested, with main variables including the radius, thickness, and slope of the CFRP loop at the anchorages. The results indicate that the mechanical behavior of the self-anchored cables is mainly determined by the thickness and radius of the CFRP loop and by increasing these characteristics, the cable's material strength can be fully exploited. With optimized anchorage configurations, the anchor efficiency of the proposed self-anchor CFRP cable system can reach 95% or larger. Additionally, finite element analysis was conducted, with good agreement between the numerical and experimental results. Finally, the influence of the radius and thickness of the CFRP loop on the anchoring capacity and the nominal anchor efficiency was further discussed based on an orthotropic thick-walled cylinder model. [ABSTRACT FROM AUTHOR]