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As a key component of a swivel bridge, the spherical hinge is a steel-concrete structure, which is susceptible to moisture damage during waiting time. In this paper, spherical hinge moisture damage prevention is investigated comprehensively from two aspects of impermeable concrete and steel-concrete interface waterproof coating. Three impermeable c...
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... this study, crushed and sharp-edged aggregates (Jiutai, China) were used for preparation of impermeable concrete. Physical properties and the gradation of coarse aggregates are listed in Table A2 and Figure 2. As the skeleton of the concrete, sand and stone are designated the skeleton. ...
Context 2
... Yinma river sand is a medium sand with a fineness modulus of 2.95, and the sand ratio is 35%. Physical properties and the gradation of the sand are listed in Table A3 and Figure 2. The physical properties and gradation of coarse aggregate and sand used in this paper meet the requirement of the specification for the mix proportion design of ordinary concrete (JGJ55-2011). ...
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Citations
... The lubrication technology of spherical hinge structures has advanced significantly alongside the progress in material science [12]. In the early stages of swivel bridge development, limited by the material science at that time, the span and tonnage of swivel bridges were small, and concrete was primarily used to construct the spherical hinge structure [13][14][15]. Although concrete-based spherical hinge structures offered significant cost-saving advantages in engineering, they have gradually fallen out of favor in the market due to their high friction coefficient and low shear strength [16,17]. ...
A spherical hinge structure is a key swivel bridge element that must be considered when evaluating friction characteristics and lubrication properties to meet the rotation requirement. Polytetrafluoroethylene (PTFE)-based spherical hinge sliders and lubrication coating have been employed for over 20 years, but with the growing tonnage of swivel bridge construction, their capacity to accommodate the required lubrication properties can be exceeded. In this manuscript, the optimal friction coefficient of the spherical hinge is obtained through the finite element analysis method. Four lubrication coatings and four spherical hinge sliders are prepared and tested through a self-developed rotation friction coefficient test, four-ball machine test, dynamic shear rheological test, and compression and shear performance test to evaluate the lubrication and friction properties of the spherical hinge structure. The results of the finite element analysis show that the optimum rotation friction coefficient of the spherical hinge structure is 0.031–1.131. The test results illustrate that the friction coefficient, wear scar diameter, maximum non-seize load, phase transition point, and thixotropic ring area of graphene lubrication coating are 0.065, 0.79 mm, 426 N, 14.6%, and 64,878 Pa/s. The graphene lubrication coating has different degrees of improvement compared with conventional polytetrafluoroethylene lubrication coating, showing more excellent lubrication properties, bearing capacity, thixotropy, and structural strength. Compressive and shear tests demonstrate that polyether ether ketone (PEEK) has good compressive and shear mechanical properties. The maximum compressive stress of PEEK is 87.7% higher than conventional PTFE, and the shear strength of PEEK is 6.07 times higher than that of PTFE. The research results can provide significantly greater wear resistance and a lower friction coefficient of the spherical hinge structure, leading to lower traction energy consumption and ensuring smooth and precise bridge rotation.
... The spherical hinge stress state is affected by material selection and structural size. Moreover, it is closely related to the starting traction torque and stability of the swivel structure [1][2][3][4]. The swivel spherical hinge is typically composed of an upper rotary table, upper spherical hinge, lower spherical hinge, lower cushion cap, central pin shaft, and other structures, which bear the vertical load from the upper bridge structure. ...
The accurate analysis of key components of a spherical hinge structure directly affects bridge quality and safety during construction. Considering the key components of a spherical joint structure as the research object, a refined calculation model for the spherical joint is established to examine its stress using finite element analysis. The influence of design parameters on the mechanical characteristics of the spherical hinge structure is systematically analyzed. The response surface method (RSM), devised using a Box–Behnken design, is used to optimize the design of the spherical hinge structure parameters. A response surface model is established to derive the scheme of the optimized spherical hinge structure design. Moreover, by comparing the structural contact stress and rotational traction force before and after optimization, the effectiveness and necessity of the spherical hinge structure optimization are verified. The result comparison shows that the maximum contact stress and rotational traction force in the spherical hinge structure after optimization are reduced by 13.86% and 8.42%, respectively, compared with those before optimization. The relative error between the calculated and predicted values is approximately 3%, indicating that the RSM is feasible for optimizing key components of the spherical hinge structure. Its optimization effect is evident. Based on the identified optimal parameters of the spherical hinge structure, a range of recommended design parameters for the key structure of the rotating spherical hinge at different load carrying capacities is established using the interpolation method, which provides a valuable reference for engineering practice.
... However, current research in bridge pavement focuses on flexible materials that allow for large deformation, such as the composite asphalt surface layer and the binding layer. In contrast, as a transition layer between the rigid layer and the flexible layer, the leveling overlay has not attracted sufficient attention [5,6]. ...
... Since the concrete specimens already reached the maximum shrinkage strain and cracked after 7 d, while the SSPP-ECC specimens had the maximum shrinkage strain after approximately 27 d, the average tensile stress and shrinkage deformation on the outer surface of the concrete at 7 d and the SSPP-ECC at 7 d and 27 d are shown in Table 5. The average tensile stress on the outer surface of the specimens can be obtained from the association of Equations (5) and (6), and the shrinkage deformation on the outer surface of the specimens can be obtained from the association of Equations (5) and (7). Since the concrete specimens already reached the maximum shrinkage strain and cracked after 7 d, while the SSPP-ECC specimens had the maximum shrinkage strain after approximately 27 d, the average tensile stress and shrinkage deformation on the outer surface of the concrete at 7 d and the SSPP-ECC at 7 d and 27 d are shown in Table 5. ...
In response to the current common disease of concrete leveling overlays of bridge pavement in China, the feasibility of using an economic SSPP-ECC with local waste superfine sand as an alternative material for a leveling overlay was proposed in this study. To evaluate the interface bonding property in the girder between the SSPP-ECC and concrete, a slant shear test and split tensile test were designed to study the interfacial shear and tensile properties of the ordinary concrete/ordinary concrete (OC/OC) and ordinary concrete/SSPP-ECC (OC/ECC), where the results showed that SSPP-ECC could significantly improve the interface shear stress and split tensile strength compared to ordinary concrete. Furthermore, the damage status of OC/ECC no longer involved fracturing along the interface; instead, each of the two substrates was partially destroyed, which revealed that OC/ECC had a high bonding effect. Moreover, a restrained shrinkage test was carried out to evaluate the shrinkage property of SSPP-ECC, where the result showed that the shrinkage strain of SSPP-ECC was slightly lower than concrete, where the average cracking time for SSPP-ECC was far longer than for ordinary concrete under the same ambient drying conditions; furthermore, the stress rate for SSPP-ECC revealed that it was a low-cracking-risk material. Meanwhile, the crack width of SSPP-ECC was only 0.1 mm after 35 d, which showed that SSPP-ECC had a more substantial crack width control capacity relative to concrete. The test results initially verified the feasibility and great potential of economic SSPP-ECC applied in a bridge pavement leveling overlay.
The construction process of Longyan Bridge was constrained by the conditions at the construction site. At the site, the operation of multiple urban arteries (one river, two railways and two highways) cannot be interrupted. Additionally, this single-pylon asymmetric cable-stayed bridge is located in a karst area. To accelerate the construction of the bridge, a swivel construction method was adopted for minimal disturbance to the traffic and environment. It was decided to launch the steel box-girder through the cast-in-situ pylon without intersecting with the traffic lines and to rotate the asymmetric superstructure by 21° via a spherical swivel system. This method allows construction preparation and implementation in the most efficient way within the available time. This paper elaborates the swivel construction of the bridge where the swivel weight is heaviest (i.e. 2.36×10⁷ kg) in a karst area. The design method for the spherical hinge is presented as an example and validated, in which a simplified method and engineering practice are integrated. Additionally, monitoring and control measures during the rotation process and weighing test are conducted to achieve the stability and safety of the construction. Useful reference describing the swivel construction is provided that can be particularly instructive for future accelerated bridge construction.
