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CONTENTS
Volume 9, Number 4, August 2020
 

Abstract
This paper deals with the effect of the mode shapes on the dynamic response of a multi-storey frame subjected to moving train loads which are modelled as loads of constant intervals with constant velocity using the finite element method. The multi-storey frame is modelled as a number of Bernoulli-Euler beam elements. First, the first few modes of the multi-storey frame are determined. Then, the effects of force span length to beam length ratio and velocity on dynamic magnification factor (DMF) are evaluated via 3D velocity-force span length to beam length ratio-DMF graphics and its 2D projections. By using 3D and 2D graphics, the directions of critical speeds that force the structure under resonance conditions are determined. Last, the mode shapes related to these directions are determined by the time history and frequency response graphs. This study has been limited by the vibration of the frame in the vertical direction.

Key Words
multi-storey frame; moving force; the finite element method; dynamic magnification factor; mode shape

Address
Salih Demirtas and Hasan Ozturka: Department of Mechanical Engineering, Dokuz Eylul University, 35397, Buca, İzmir, Turkey

Abstract
A mathematical model of electro-thermoelasticity subjected to memory-dependent derivative (MDD) heat conduction law is applied to a one-dimensional problem of a thermoelectric spherical cavity exposed to a warm stun that is an element of time in the presence of a uniform magnetic field. Utilizing Laplace transform as an instrument, the issue has been fathomed logically within the changed space. Numerical inversion of the Laplace transform is carried for the considered distributions and represented graphically. Some comparisons are shown in the figures to estimate the effects of MDD parameters and thermoelectric properties on the behavior of all considered fields.

Key Words
electro-thermoelasticity; memory-dependent derivative; thermoelectric properties; spherical cavity; Laplace transforms; numerical results

Address
Sayed I. El-Attar: Department of Mathematics, Faculty of Science, Northern Border University, Arar, Saudi Arabia
Mohamed H. Hendy: Department of Mathematics, Faculty of Science, Northern Border University, Arar, Saudi Arabia; Department of Mathematics, Faculty of Science, Al Arish University, Al Arish, Egypt
Magdy A. Ezzat: Department of Mathematics, College of Science and Arts, Al-Qassim University, Al-Bukairyah, Saudi Arabia; Department of Mathematics, Faculty of Education, Alexandria University, Alexandria, Egypt

Abstract
The present research deals with the time-harmonic deformation in transversely isotropic magneto thermoelastic solid with two temperature (2T), rotation due to inclined load and laser pulse. Generalized theory of thermoelasticity has been formulated for this mathematical model. The entire thermo-elastic medium is rotating with uniform angular velocity and subjected to thermally insulated and isothermal boundaries. The inclined load is supposed to be a linear combination of a normal load and a tangential load. The Fourier transform techniques have been used to find the solution to the problem. The displacement components, stress components, and conductive temperature distribution with the horizontal distance are computed in the transformed domain and further calculated in the physical domain using numerical inversion techniques. The effect of angle of inclination of normal and tangential load for Green Lindsay Model and time-harmonic source for Lord Shulman model is depicted graphically on the resulting quantities.

Key Words
thermal laser pulse; time-harmonic sources; transversely isotropic thermoelastic; rotation; inclined load; Magneto thermoelastic solid; generalized thermoelasticity

Address
Parveen Lata, Iqbal Kaur: Department of Basic and Applied Sciences, Punjabi University, Patiala, Punjab, India
Kulvinder Singh: Kurukshetra University Kurukshetra, Haryana, India

Abstract
Due to susceptibility of bridges in the past earthquakes, vulnerability assessment and strengthening of bridges has gained a particular significance. The objective of the present study is to employ an analytical method for the development of fragility curves, as well as to investigate the effect of strengthening on the RC box-girder bridges. Since fragility curves are used for pre- and post-earthquake planning, this paper has attempted to adopt the most reliable modeling assumptions in order to increase the reliability. Furthermore, to acknowledge the interaction of soil, abutment and pile, the effect of different strengthening methods, such as using steel jacketing and FRP layers, the effect of increase in the bridge pier diameter, and the effect of vertical component of earthquake on the vulnerability of bridges in this study, a three-span RC box-girder bridge was modeled in 9 different cases. Nonlinear dynamic analyses were carried out on the studied bridges subjected to 100 ground motion records via OpenSEES platform. Therefore, the fragility curves were plotted and compared in the four damage states. The results revealed that once the interaction of soil and abutment and the vertical component of the earthquake are accounted for in the calculations, the median fragility is reduced, implying that the bridge becomes more vulnerable. It was also confirmed that steel jackets and FRP layers are suitable methods for pier strengthening which reduces the vulnerability of the bridge.

Key Words
vulnerability assessment; steel jacketing; FRP layers; vertical component of earthquake; RC box-girder bridge

Address
Ali Naseri: Department of Structural Engineering, Babol Noshirvani University of Technology, Iran
Alireza Mirzagoltabar Roshan: Department of Structural Engineering, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Iran
Hossein Pahlavan: Department of Earthquake Engineering, Shahrood University of Technology, Iran
Gholamreza Ghodrati Amiri: Center of Excellence for Fundamental Studies in Structural Engineering, School of Civil Engineering, Iran University of Science and Technology, Iran

Abstract
Analytical investigation of the fracture of inhomogeneous beam with two parallel lengthwise cracks is performed. The thickness of the beam varies continuously along the beam length. The beam is loaded in three-point bending. Two beam configurations with different lengths of the cracks are analyzed. The two cracks are located arbitrary along the thickness of the beam. Solutions to the strain energy release rate are derived assuming that the material has non-linear elastic mechanical behavior. Besides, the beam exhibits continuous material inhomogeneity along its thickness. The balance of the energy is analyzed in order to derive the strain energy release rate. Verifications of the solutions are carried-out by considering the complementary strain energy stored in the beam configurations. The influence of the continuous variation of the thickness along the beam length on the lengthwise fracture behavior is investigated. The dependence of the lengthwise fracture on the lengths of the two parallel cracks is also studied.

Key Words
lengthwise fracture; inhomogeneous beam; material non-linearity; three-point bending; variable thickness

Address
Victor I. Rizov: Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy,
1 Chr. Smirnensky blvd., 1046 - Sofia, Bulgaria


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