Current Issue : July - September Volume : 2017 Issue Number : 3 Articles : 5 Articles
Short fibers have been widely used to prepare the fiber reinforced asphalt concrete (FRAC).However, internal interactions between\nfiber and other phases of asphalt concrete are unclear although experimental methods have been used to design the FRAC\nsuccessfully. In this paper, numerical method was used to investigate the reinforced mechanism of FRAC from microperspective.\n2D micromechanicalmodel of FRAC was established based onMonte Carlo theory. Effects of fiber length and content on stress state\nof asphalt mortar, effective modulus, and viscoelastic deformation of asphalt concrete were investigated. Indirect tensile stiffness\nmodulus (ITSM) test and uniaxial creep test were carried out to verify the numerical results. Results show that maximum stress of\nasphalt mortar is lower compared to the control concrete when the fiber length is longer than 12 mm. Fiber reduces the stress level\nof asphalt mortar significantly. Fiber length has no significant influence on the effective modulus of asphalt concrete. Fiber length\nand content both have notable impacts on the viscoelastic performance of FRAC. Fiber length should be given more attention in\nthe future design of FRAC except the content....
This paper analyzes the influences of important structural design parameters on the wind-induced response of cross-rope\nsuspension tower-line. A finite element model of cross-rope suspension tower-line system is established, and the dynamic timehistory\nanalysis with harmonic wave superposition method is conducted. The two important structural design parameters such\nas initial guy pretension and sag-span ratio of suspension-rope are studied, as well as their influences on the three wind-induced\nvibration responses such as tensile force on guys, the reaction force on mast supports, and the along-wind displacement of the mast\ntop; the results show that the value of sag-span ratio of suspension-rope should not be less than 1/9 and the value of guy pretension\nshould be less than 30% of its design bearing capacity. On this occasion, the tension in guys and compression in masts would be\nmaintained in smaller values, which can lead to a much more reasonable structure....
Bricks of low elastic modulus are occasionally used in some developing countries, such as Indonesia and India.Most of the previous\nresearch efforts focused on masonry structures built with bricks of considerably high elastic modulus. The objective of this study is\nto quantify the equivalent elastic modulus of lower-stiffness masonry structures, when themortar has a higher modulus of elasticity\nthan the bricks, by employing finite element (FE) simulations and adopting the homogenization technique.The reported numerical\nsimulations adopted the two-dimensional representative volume elements (RVEs) using quadrilateral elements with four nodes.\nThe equivalent elastic moduli of composite elements with various bricks and mortar were quantified. The numerically estimated\nequivalent elastic moduli from the FE simulations were verified using previously established test data. Hence, a new simplified\nformula for the calculation of the equivalent modulus of elasticity of such masonry structures is proposed in the present study....
In this study,Navier�s solution for the analysis of simply supported rectangular plates is extended to consider rigid internal supports.\nThe proposed method offers amore accurate solution for the bendingmoment at the critical section and therefore serves as a better\nanalytical solution for design purposes. To model the plate-support interaction, the patched areas representing the contact between\nthe plate and supports are divided into groups of cells.Theunknown internal reactions at the centers of the divided cells are obtained\nby satisfying the compatibility conditions at the centers of the cells. Three numerical examples are presented to demonstrate the\naccuracy of the proposed analytical solution. The given examples reveal good agreements with those obtained by the finite element\nanalysis. In addition, they show the advantage of the new solution as compared to the existing analytical solution which inaccurately\nestimates the location and magnitude of the maximum bending moment....
The modeling of cracks and identification of dam behavior changes are difficult issues in dam health monitoring research. In this\npaper, a time-varying identificationmodel for crackmonitoring data is built using support vector regression (SVR) and the Bayesian\nevidence framework (BEF). First, the SVR method is adopted for better modeling of the nonlinear relationship between the crack\nopening displacement (COD) and its influencing factors. Second, the BEF approach is applied to determine the optimal SVR\nmodeling parameters, including the penalty coefficient, the loss coefficient, and the width coefficient of the radial kernel function,\nunder the principle that the prediction errors between the monitored and the model forecasted values are as small as possible.\nThen, considering the predicted COD, the historical maximum COD, and the time-dependent component, forewarning criteria\nare proposed for identifying the time-varying behavior of cracks and the degree of abnormality of dam health. Finally, an example\nof modeling and forewarning analysis is presented using two monitoring subsequences froma real structural crack in the Chencun\nconcrete arch-gravity dam. The findings indicate that the proposed time-varyingmodel can provide predicted results that aremore\naccurately nonlinearity fitted and is suitable for use in evaluating the behavior of cracks in dams....
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