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As the main load-bearing component of the bridge structure, the cable is damaged by the impact from time to time, so it is very important to clarify its impact resistance capacity. Based on the method of the drop-weight test, this article mainly studies the degradation law of the mechanical properties of epoxy-coated steel strand (ECSS) under the impact load. Through the impact test of ECSS under different working conditions, the influence law of prestress, impact energy, initial defects and other factors on the impact resistance of the steel strand was revealed. Then, the difference of the impact resistance of ECSS and ordinary steel strand (OSS) was verified under the same impact conditions. Finally, the failure mechanism and the residual-bearing capacity of ECSS were analyzed through the secondary impact test. The results show that the initial prestress is helpful to improve its impact resistance when it is less than 0.11 f u {f}_{{\rm{u}}} , and exceeding this value will accelerate its failure process. The effect of impact height on the strain at the impact point of ECSS is significantly greater than that near the anchor end. ECSS has better energy absorption characteristics than OSS. The impact resistance of ECSS with initial defects is very sensitive to the impact energy. The influence on outer strand in the secondary impact is significantly higher than the central strand, and its residual tensile capacity still has 0.85 f u {f}_{{\rm{u}}} .

A new multi-scale numerical method is proposed to simulate crack propagation in reinforced concrete structures. First of all, a three-phase composite material model is used to build the concrete structures at meso-level. And a modified Weibull distribution model is introduced to describe further the microscopic characteristics of concrete. Then different constitutive relations are adopted for components of concrete and reinforcing bars. Next, the numerical program written in ANSYS parametric design language and tool control language is executed to investigate the fracture behavior of reinforced concrete structures. The program, which can check the development of multiple cracks, is greatly improved by contrast with traditional methods. Finally, relevant experiments are conducted for comparing with the numerical results. The analysis results indicate that the program has strong robustness. Moreover, a good agreement is achieved between simulation results and experimental observation.

The existing shear design theories for hybrid beams with corrugated steel webs (CSWs) used in China and Japan were originally proposed for only prismatic hybrid beams with CSWs. The traditional calculation method assumes that the bending stiffness and axial stiffness of a beam with CSWs are provided by the top and bottom concrete flanges, while the shear stiffness is contributed entirely by the CSWs. However, due to the influence of the Resal effect on a non-prismatic hybrid beam with CSWs, the calculated shear stress of the CSWs will be overpredicted if the shear capacities of the top and bottom concrete flanges are ignored (especially for the case of an inclined bottom flange). These traditional assumptions may no longer be applicable to non-prismatic structural members. Considering the Resal effect and accordion effect of non-prismatic beams with CSWs, this study proposed a practical unified calculation formula suitable for calculating the shear stresses of prismatic and non-prismatic hybrid beams with CSWs. The accuracy and adaptability of this unified calculation formula were verified through prismatic and non-prismatic beam model tests as well as finite element simulations. Moreover, the authors quantitatively discussed the calculation errors of the traditional calculation assumptions for non-prismatic beams with CSWs. In addition, a finite element parameter analysis was performed on a non-prismatic beam with CSWs near the support to clarify the applicable conditions of the unified calculation formula. The numerical results show that when the inclination angle of the bottom flange varies within the range of 0° to 20°, the calculation error of the proposed unified calculation formula is controlled to within 15%, exhibiting good adaptability to changes in the inclination angle. The unified calculation formula can still predict the shear stresses in tapered CSWs with an error of less than 20% when the sum of the thicknesses of the top and bottom concrete flanges does not exceed 20% of the total beam height. It is expected that this study can further develop the shear stress calculation theory for non-prismatic beams with CSWs, thus providing a reference for the reasonable design of tapered CSWs.

This study investigates the mechanical properties of carbon fiber reinforced polymer (CFRP) cable at the anchoring region where arrange the adhesive material with different mediums aiming at reducing the high stress concentration. The 3D finite element (FE) model was established based on cable force of 100t and 1000t, and its accuracy was verified by experimental results. The effects of geometrical dimensions and mediums stiffness on anchoring capacity of the cable was studied. The results show that the proposed anchorage gets high anchoring efficiency. The gradient variation of the stiffness of the adhesive material can effectively reduce the stress crest of the cable at the anchorage region. The distributions of the radial and shear stress of the cable at the anchorage region become comparatively flat with the increase in the number of segments. The variation stiffness and length ratio have the main influence on the stress of the cable in three orientations. Friction coefficient and internal taper have the secondary effects on the radial stress and the axial displacement. Anchor length and thickness of adhesive material only affect the radial stress. Anchorage design should primarily focus on the stiffness and length ratio of the adhesive material. The anchoring method proposed in this paper is helpful to anchor multi-tendon cables efficiently, and promote the application of high-capacity FRP cables in large-span spatial structure.

The world’s oldest wooden pagoda was built with no nails nearly 1000 years ago in Yingxian, China. During the past ten centuries the 67 m tall building has survived countless earthquakes, thunderstorms and wars. To understand its remarkable structural resilience and durability, a comprehensive analysis has been carried out. This paper describes the particular features of the building, including the extensive use of strong but flexible, multi-layered ‘dougong’ brackets, semi-rigid timber joints and the lack of a structural connection to the foundation. These characteristics are then analysed to determine how they function under extreme loading. A combination of energy-absorbing design, good drainage, sound foundations and woodworm-eating swallows appears to explain its extraordinary longevity.

In this paper, a random-forest-based method was proposed for the classification and localization of Attention-Deficit/Hyperactivity Disorder (ADHD), a common neurodevelopmental disorder among children. Experimental data were magnetic resonance imaging (MRI) from the public case-control dataset of 3D images for ADHD-200. Each MRI image was a 3D-tensor of 121×145×121 size. All 3D matrices (MRI) were segmented into the slices from each of three orthogonal directions. Each slice from the same position of the same direction in the training set was converted into a vector, and all these vectors were composed into a designed matrix to train the random forest classification algorithm, then, the well-trained RF classifier was exploited to give a prediction label in correspondence direction and position. Diagnosis and location results can be obtained upon the intersection of these three prediction matrices. The performance of our proposed method was illustrated on the dataset from New York University (NYU), Kennedy Krieger Institute (KKI) and full datasets, the results show that the proposed methods can archive more accuracy identification in discrimination of ADHD, and can be extended to the other practices of diagnosis. Moreover, another suspected region was found at the first time.

In this study, the internal microstructure of the forewings of Allomyrina dichotoma is investigated by scanning electron microscopy (SEM) analysis. The results of SEM test show that the inner microstructure of the forewings possesses an integrated sandwich-like plate supported by trabeculae, which is composed of upper and lower skins of unequal thicknesses, and a honeycomb core with trabeculae. Beetle forewing is a natural composite material composed of chitin fibres and proteins. Also, based on the micro dimensions of the forewings observed by SEM, two groups of micro finite element (FE) models of the forewings (i.e., core with trabeculae and core without trabeculae) are established to compare and comprehensively understand the effect of trabeculae on the mechanical properties of the forewings. The FE simulation results demonstrate that the trabeculae could effectively (1) improve the stress state on the upper skin, lower skin, and core layer of the forewings, (2) improve the overall bending stiffness of the forewings, (3) enhance the peeling resistance between the skins and core layer, and (4) improve the buckling strength of the thin-walled core layer. The unique forewing structure of the Allomyrina dichotoma can provide an excellent bionic model for optimizing the traditional honeycomb panel structure.

To study the interfacial bond-slip performance of concrete-filled square steel tubes (CFSSTs), taking the core concrete strength, slenderness ratio, and width-to-thickness ratio as the influencing factors; 9 specimens were designed with 3 factors and 3 levels for the orthogonal test method. In addition, different from the above 9 specimens, one specimen without rust removal was designed for the purpose of comparison. Based on the bond stress distribution and deformation coordination relationships between the specimens during the push-out tests, a theoretical formula for calculating the relative slip of a CFSST was deduced. The results show that with the increase of load, the relative slip at the loading ends was earlier than that at the free ends of the specimens; the interfacial bond failure and relative slip gradually developed from the two ends towards the centre of the specimens; the increase of the bond stress in the middle part was faster than that at the ends of the specimens. The order of these factors from main to secondary is the presence of rust in the inner wall of the square steel tube, the slenderness ratio, the core concrete strength, and the width-to-thickness ratio.

This paper presents a practical method for automatically generating optimal strut-and-tie models (STMs) in anchorage zones. In the proposed approach, a new microtruss element pattern is created to build ground structures. In certain conditions, the approach could also be improved by combining the microtruss grids with solid elements. Furthermore, the formula for the cross-sectional areas of bar elements in the microtruss grid is deduced for the purpose of replacing the continuum structures built by solid elements with discrete structures built by truss elements. Then, three examples are illustrated to demonstrate the capability of the proposed optimization procedure to find the optimal STMs of anchorage zones. The existing solutions and numerical experiments indicate that the proposed approach accurately reflects the actual load-transfer mechanism in anchorage zones. The method can be used in practice, especially in the design of some disturbed regions (D-regions) in which optimal STMs cannot be o...

Based on the condition of static equilibrium and the equivalent law of shearing stress of an infinitesimal segment, this paper provides a strict derivation of the general formula for shearing stress in a nonuniform box girder with corrugated steel webs in the elastic stage. The derived formula is applied to investigate the stress distribution in concrete flanges and corrugated steel webs. Additional shear stress was found to be caused by the bending moment, and the axial force should be included in calculations from the effect of variable cross sections, which are quite different from that of the uniform cross sections. Moreover, because the additional shear stress of the bending moment is self-balanced, the shear force distribution can be adjusted between the concrete slabs and steel webs. Research shows that shear stress decreases markedly in the webs, whereas the shear stress apparently increases in the inclined bottom flange in the action of the bending moment. This study also found and explai...

Despite the construction of several curved prestressed concrete girder bridges with corrugated steel webs (CSWs) around the world, their shear behavior has seldom been investigated. Accordingly, this paper substitutes the lack of available information on the global elastic shear buckling of a plane curved corrugated steel web (PCCSW) in a curved girder. This is based on the equilibrium equations and geometric equations in the elastic theory of classical shells, combined with the constitutive relation of orthotropic shells. Currently, the global elastic shear buckling process of the PCCSW in a curved girder is studied, for the first time in literature, with an equivalent orthotropic open circular cylindrical shell (OOCCS) model. The governing differential equation of global elastic shear buckling of the PCCSW, as well as its buckling strength, is derived by considering the orthotropic characteristics of a corrugated steel web, the rational trigonometric displacement modes, Galerkin&rsquo, s method and variational principles. Additionally, the accuracy of the proposed theoretical formula is verified by comparison with finite element (FE) results. Moreover, the expressions of the inner or outer folded angle and radius of curvature are given by the cosine theorem of the trigonometric function and inverse trigonometric function. Subsequently, parametric analysis of the shear buckling behavior of the PCCSW is carried out by considering the cases where the radius of curvature is constant or variable. This parametric analysis highlights the effects of web dimensions, height-to-thickness ratio, aspect ratios of longitudinal and inclined panels, corrugation height, curvature radius and folded angles on the elastic shear buckling strength. As a result, this study provides a theoretical reference for the design and application of composite curved girders with CSWs.