Search

Fiber can absorb asphalt binder and therefore reinforce and stabilize the asphalt mixture structure and also prevent the asphalt from the leaking, which occurs in the process of mixing and transport. In this study, three kinds of fiber (polyester fiber, polypropylene fiber, and lignin fiber) are used to evaluate the relationship between the fiber types and mechanic performance of SMA-13 fiber asphalt mixture, which is specially designed for field tests of high-speed vehicles on pavements. The micro-surface characteristics of fiber and aggregates were studied by SEM and image analysis. Marshall stability and splitting strength were used to measure the properties of the asphalt mixture. In addition, a field test, including measures for curve-section edge, curve-section center, straight-section edge, and straight-section center, was conducted to evaluate the skid resistance of the high-speed vehicles that test field pavement. The results show that the Marshall stabilities of asphalt mixture with three kinds of fibers have been improved, whereas the stability of asphalt mixture prepared by polypropylene fiber and polyester fiber particularly increased before immersion. Among the three kinds of fiber asphalt mixtures, the polyester fiber asphalt mixture has enhanced water susceptibility. Skid resistance in the field test indicated that high skid resistance and good surface-texture depth were achieved.

This paper establishes an empirical formula to predict the strain amplitude effect. A viscoelastic constitutive model—the superposition of a hyperelastic model and a viscoelastic model—is constructed based on the laws of thermodynamics. The Mooney–Rivlin model and the Prony series are employed for uniaxial tension testing. The empirical formula is derived using a hysteresis loop; it obtains results that are in agreement with the experimental results of dynamic mechanical analysis (DMA). The empirical formula proposed in this paper has certain accuracy in predicting the dynamic modulus under different strain amplitudes.

Reducing or degrading nitrogen oxides (NOx) emitted by automobile exhausts has diversified ways. This paper presents a solution to degrade NO by Nano-sized titanium dioxide (Nano-TiO2) mixed with coating materials for traffic marking on road pavements. The effect on degradation was evaluated by adopting a simple laboratory test with statistical analysis. During the test, five different contents of Nano-TiO2, 2%, 3%, 4%, 5%, and 6%, mix with a coating material for pavement marking, followed by an interpretation of the micro mechanism of degradation effect. The results show that the pavement marking coatings mixed with Nano-TiO2 has a good performance on NO degradation. The effect of degradation is increased with increasing the content of Nano-TiO2 particles, however. At the same time, a peak value with about 70% of the maximum removing rate existed when applying 4% Nano-TiO2 due to the agglomeration phenomenon for nanoparticles close to each other for adding more Nano-TiO2. The methods to reduce agglomeration are also suggested, and a routine field test for all potential traffic coating materials is recommended in this study.

Rubber has been widely addressed as anti-vibration components in long time service structure, time-dependent behavior is an undesirable problem contributing to the low acceptance by applications. In this paper, a hyper-viscoelastic model is established so that the tension behavior of rubber is simulated and analyzed. This model is constructed by a hyperelastic element in parallel with a viscoelastic model and Polynomial model, which was examined by uniaxial tension test, was proved validly to be hyperelastic. A fairly good agreement between the tension creep test and analytical results claimed that the Generalized Maxwell model with six variables is suitable for expression of hyper-viscoelastic method. In this paper, by combining the results of uniaxial tensile and tensile creep experiments, a hyper-viscoelastic constitutive model is established, and the experiment is simulated compared with the experimental results.

As the height of bridge increases, more and more high piers are designed with diaphragms to ensure their stability. However, the insertion of the diaphragms will have a significant impact on the speed and efficiency of the pier construction. For the stability problem of hollow thin-walled high piers, the numerical simulation of the model with or without diaphragms is carried out to compare and analyze the force mode, ultimate bearing coefficient and deformation characteristics of high pier of curved bridge from the perspectives of full bridge buckling analysis, high pier integral stability and high pier local stability in this paper. Studies have shown that the effect of installing concrete diaphragms on the stability of such single hollow thin-walled high piers is not obvious. If the wall thickness of the high pier meets the requirements for strength and stiffness and the theoretically calculated maximum allowable width-to-thickness ratio, the long-span continuous rigid frame curved bridge high piers may not be provided with diaphragms.

As the vibration damping component of the bridge, the rubber bearings are not only supporting the weight of the beam but also bearing the small vibration load of various moving loads.a#13; The dynamic characteristics of rubber are not only dependent on frequency and temperature, but also closely related to large deformation under static behavior. To investigate pre-strain effect, static and dynamic compression experiments were carried out on a cylindrical chloroprene rubber specimen, and the storage modulus and loss modulus under different pre-strain were obtained, the test results show that the storage modulus increases with the increase of pre-strain, while the loss modulus decreases. An empirical formula to describe the relationship between storage modulus, loss modulus and pre-strain. a#13

Stay cable is one of the main components of cable stayed bridge to bear loads. Due to its large flexibility, small quality and small damping, various of harmful vibrations could happen easily under the external excitations. Rain-wind-induced vibration is the strongest form of vibrations. Under the joint action of wind and rain, big vibration will take place. The vibration is relatively complex because the vibration belongs to three-phase coupling vibration. According to the existing water balance equation of rain-wind-induced vibration numerical analysis, the vibration of cable in different wind speed, wind directions and different waterway directions are respectively analyzed, the results show that the rain-wind-induced vibration of cable is greatly influenced by wind directions, and waterway directions has a very significant impact as well.