Key Engineering Materials Vol. 815

Abstract: Based on the finite element model, the propagation characteristics of Rayleigh wave in layered structure is studied in this paper, the time-domain characteristics of wave form is analysed under different working conditions, and the identification parameters of surface wave method to detect the layered concrete is proposed. When the incident elastic wave propagates to the defect, due to the barrier effect of the defect, a part of the incident R wave is converted into a reflected R wave, which propagates along the track plate to the surface; the other part of the R wave is converted into a transmitted R wave, along the concrete. The energy amplitude can be used as one of the parameters to identify defects in the layered concrete structure.

Abstract: The ocean islands are far from inland and the concrete sandstone aggregates are scarce. In this paper, high-performance seawater all-coral concrete was developed by seawater mixing and room temperature maintenance design, and by optimizing the water-to-binder ratio, regulating internal curing, changing auxiliary cementing materials and blending ratio, incorporating expansion agent, adjusting fiber blending, etc. Combined with the consideration of work performance and mechanical properties, the concrete self-shrinkage is adjusted to further optimize the mix design. The mechanical properties of the optimized high-performance seawater all-coral concrete were studied, and the relevant durability tests were carried out according to the natural environment characteristics of the island. This is of great significance to the construction of island projects, repair and construction, and construction of protective projects [1].

Abstract: In order to improve the mechanical behaviour of bridge steel hoops, the plate shell finite element models of several steel hoops were established by using the general finite element software ABAQUS. Through changing the structural parameters of the stiffening plates, the influence of the stiffening plates on the mechanical properties of the steel hoops was explored. The calculation results show that the stress distribution at both ends of the steel hoop is uneven and there is a phenomenon of stress concentration. The spacing of stiffening plates has great influence on the mechanical properties of steel hoop. Some measures to improve the mechanical properties of steel hoop are given.

Abstract: In the construction of high-speed railway bridge, the stress of Bailey beam is much higher than that of other parts due to the large local compressive stress and bending moment at the fulcrum. To solve this problem, this paper proposes a structural measure of adding double I-steel cushion between Bailey beam and top beam to alleviate the larger stress at the fulcrum and make the support more uniform. Based on the Bailey beam support system of cast-in-situ high-speed railway bridge of Lianshui County super large bridge, the multi-scale finite element model of Bailey beam support is established by ABAQUS general finite element software, and the influence law of structural parameters of double-jointed I-steel cushion on support stress is analyzed. The research shows that the rigidly of the double-jointed I-beam cushion should not be too large or too small. When the length is appropriate, it can effectively alleviate the problem of excessive stress at the fulcrum of Bailey beam, and is a safe, economical and simple new structural measure.

Abstract: In this paper, the water penetration resistance of rubber aggregate concrete is studied by using the water penetration height method. The experiment results show that: Under the condition of the same dosage, the greater the fineness module, the better the impermeability. Under the condition of the same particle size, the higher the dosage, the better the impermeability. Moreover, the strength of rubber aggregate concrete cannot determine its impermeability. The impermeability of rubber aggregate concrete is analyzed by binary regression analysis. The results show that: Rubber aggregate content and fineness module have obvious influence on the water permeability of concrete. The established permeability regression equation can estimate the permeability height of rubber aggregate concrete, which has certain guiding significance for practical engineering.