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Ryan K.L.,University of Nevada, Reno | Dao N.D.,Ho Chi Minh City University of Architecture
Journal of Structural Engineering (United States) | Year: 2016

This paper focuses on a horizontal-vertical coupling effect observed in a full-scale shake table experiment of a 5-story moment frame building isolated with triple pendulum bearings. A significant increase or amplification of the horizontal floor accelerations was observed during three-dimensional (3D) shaking compared to XY (horizontal only) shaking with comparable input motions. The coupling phenomenon is explained by analytical and numerical simulation of a single degree-of-freedom (rigid mass) structure and multistory cantilever structure subjected to simplified sinusoidal motions, both isolated with triple pendulum bearings. The results of the simplified numerical study are extended to explain the horizontal-vertical coupling in the full-scale experiment, which are also validated by numerical modeling of the test structure. The vertical component of ground acceleration is shown to introduce a high-frequency component into the base shear that can excite higher modes of the base-isolated structure. The phenomenon is possible in any multistory structure isolated with friction bearings, and should be evaluated on a case-by-case basis. © 2015 American Society of Civil Engineers. Source

Valizadeh N.,Bauhaus University Weimar | Bui T.Q.,University of Siegen | Vu V.T.,Ho Chi Minh City University of Architecture | Thai H.T.,Hanyang University | Nguyen M.N.,Ruhr University Bochum
International Journal of Applied Mechanics | Year: 2013

Buckling, free and forced vibration analyses of orthotropic plates are studied numerically using Isogeometric analysis. The present formulation is based on the classical plate theory (CPT) while the NURBS basis function is employed for both the parametrization of the geometry and the approximation of plate deflection. An efficient and easy-to-implement technique is used for imposing the essential boundary conditions. Numerical examples for free and forced vibration and buckling of orthotropic plates with different boundary conditions and configurations are considered. The numerical results are compared with other existing solutions to show the efficiency and accuracy of the proposed approach for such problems. © 2013 Imperial College Press. Source

Lan T.T.H.,Ho Chi Minh City University of Architecture
Jordan Journal of Civil Engineering | Year: 2013

The approximate solutions of stresses and displacements were obtained for fixed-fixed anisotropic beams subjected to uniform load. A stress function involving un-known coefficients was constructed, and the general expressions of stress and displacement were obtained by means of airy stress function method. Two types of the description for the fixed end boundary condition were considered. The introduced unknown coefficients in stress function were determined by using the boundary conditions. The approximate solutions for stresses and displacements were finally obtained. Numerical tests show that the solutions agree with the FEM results. These solutions are achieved by using Maple software. © 2013 JUST. All Rights Reserved. Source

Nguyen V.-H.,Ho Chi Minh City University of Architecture | Remond S.,University of Lille Nord de France | Gallias J.-L.,Cergy-Pontoise University
Cement and Concrete Research | Year: 2011

The influence of water to cement ratio, HRWRA content and viscosity modifying admixture content on the rheological characteristics of cement grouts considered as Herschel-Bulkley fluids is studied experimentally. Results show that cement grouts without chemical admixtures and cement grouts containing only a viscosity modifying admixture present a shear-thinning behaviour with an approximately constant value for the exponent n of Herschel-Bulkley model. On the contrary, grouts containing a HRWRA content near the saturation point exhibit quasi Binghamian behaviour. The Herschel-Bulkley model describes properly the rheological behaviour of cement grouts without chemical admixtures. It can be applied correctly to grouts containing HRWRA and/or viscosity modifying admixture in a shear rate range comprised between 4 s- 1 and 100 s- 1 and can be used to predict satisfactorily the Marsh cone flow time of cement grouts of widely varying compositions. © 2010 Elsevier Ltd. All rights reserved. Source

Tran P.V.,Kanazawa University | Tran P.V.,Ho Chi Minh City University of Architecture | Maegawa K.,Kanazawa University | Fukada S.,Kanazawa University
Computers and Geotechnics | Year: 2013

This study uses a numerical procedure, previously validated with data from full-scale experiments, to investigate the performance of a modified prototype wire-rope fence to provide protection against rockfall. The cost-reducing modifications are increased post spacing and fewer wire netting layers. The numerical procedure provides the nonlinear response of the prototype under various impact conditions and insights into each component's role in dissipating impact energy. A simple but effective method to increase fence capacity is also developed. Finally, the use of two units of the prototype to protect a wide area is investigated employing the numerical procedure. © 2013 Elsevier Ltd. Source

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