Abstract
This study deals with the assessment of low and mid rise multi-story buildings made of stone and /or brick, composite steel and masonry slabs from the sixties, known to be vulnerable to seismic hazard using the \"vulnerability index\" method based on buildings survey following Ain Temouchent (1999) and Boumerdes (2003) earthquakes, from where vulnerability curves are constructed using the
translation method. The results obtained for the case study confirm what has been observed in situ.
Address
F. Djaalali: Department of Civil Engineering, University M\'Hamed Bouguara, Boumerdes, Algeria
M. Bensaibi, N. Bourahla: Department of Civil Engineering, University Saad Dahleb, Blida, Algeria
L. Davenne: Laboratoire Energetique Mecanique Electromagnetisme, University Paris Ouest, Paris, France
Abstract
Current seismic codes require from the seismically designed structures to be capable to withstand inelastic deformation. Many studies dealt with the development of different inelastic spectra with the aim to simplify the evaluation of inelastic deformation and performance of structures. Recently, the concept of inelastic spectra has been adopted in the global scheme of the performance-based seismic design through capacity-spectrum methods. In this paper, the median of the ductility demand ratio for 80
ground motions are presented for different levels of normalized yield strength, defined as the yield strength coefficient divided by the peak ground acceleration (PGA). The influence of the post-to-preyield stiffness ratio on the ductility demand is investigated. For fixed levels of normalized yield strength, the median ductility versus period plots demonstrated that they are independent of the earthquake magnitude and epicentral distance. Determined by regression analysis of the data, two design equations have been developed; one for the ductility demand as function of period, post-to-preyield stiffness ratio, and normalized yield strength, and the other for the inelastic deformation as function of period and peak ground acceleration valid for periods longer than 0.6 seconds. The equations are useful in estimating the ductility and inelastic deformation demands for structures in the preliminary design. It was found that the post-to-preyield stiffness has a negligible effect on the ductility factor if the yield strength coefficient is greater than the PGA of the design ground motion normalized by gravity.
Key Words
inelastic spectra; ductility; capacity-spectrum method; ground motion
Address
Cheikh Benazouz: National Center for Applied Research in Earthquake Engineering, Hussein Dey, Algiers, Algeria
Leblouba Moussa and Zerzour Ali: High National School of Public Works, ENSTP, BP. 32, Garidi I, Vieux Kouba 16051, Algiers, Algeria
Abstract
An effective design technique for symmetrical coupled shear walls is presented. Proposed formulation including assumptions and steps with mathematical formulation has been elaborated to make the design technique. An example has been considered to validate the technique with the DRAIN-3DX (1993) and SAP V 10.0.5 (2000) nonlinear programs. Parametric study has also been considered to find
out the limitations along with remedial action of this technique. On the other hand, nonlinear static analysis is considered to determine the response reduction factor of coupled shear walls. Finally, it has been concluded in this paper that the proposed design technique can be considered to design the coupled shear walls under seismic motion.
Address
Dipendu Bhunia: Civil Engineering Department, BITS Pilani, Pilani-333031, Rajasthan, India
Vipul Prakash: Department of Civil Engineering, IIT Roorkee, India
Ashok D. Pandey: Department of Earthquake Engineering, IIT Roorkee, India
Abstract
This article studies the secondary resonances of a clamped-clamped microresonator under combined electrostatic and piezoelectric actuations. The electrostatic actuation is induced by applying the AC-DC voltage between the microbeam and the electrode plate that lies at the opposite side of the microbeam. The piezoelectric actuation is induced by applying the DC voltage between upper and lower sides of piezoelectric layer. It is assumed that the neutral axis of bending is stretched when the microbeam is deflected. The drift effect of piezoelectric layer (the phenomenon where there is a slow increase of the free strain after the application of a DC field) is neglected. The equations of motion are solved by using the multiple scale perturbation method. The system possesses a subharmonic resonance of
order one-half and a superharmonic resonance of order two. It is shown that using the DC piezoelectric actuation, the sensitivity of AC-DC electrostatically actuated microresonator under subharmonic and superharmonic resonances may be tuned. In addition, it is shown that the tuning domain of the microbeam under combined electrostatic and piezoelectric actuations at subharmonic and superharmonic conditions is larger than the tuning domain of microbeam under only the electrostatic actuation.
Abstract
Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edgenotched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six
thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, ozz /v (oxx + oyy) contours at the crack front are presented as a useful means to analyze the stress state.
Key Words
SENT; thickness; mixed mode; crack front mesh
Address
Shafique M.A. Khan: Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia
Abstract
This paper deals with determining the fundamental frequency of tall buildings that consist of framed tube, shear core, belt truss and outrigger systems in which the framed tube and shear core vary in size along the height of the structure. The effect of belt truss and outrigger system is modeled as a concentrated rotational linear spring at the belt truss and outrigger system location. Many cantilevered tall structures can be treated as cantilevered beams with variable cross-section in free vibration analysis. In
this paper, the continuous approach, in which a tall building is replaced by an idealized cantilever continuum representing the structural characteristics, is employed and by using energy method and Hamilton\'s variational principle, the governing equation for free vibration of tall building with variable distributed mass and stiffness is obtained. The general solution of governing equation is obtained by making appropriate selection for mass and stiffness distribution functions. By applying the separation of variables method for time and space, the governing partial differential equation of motion is reduced to an ordinary differential equation with variable coefficients with the assumption that the transverse
displacement is harmonic. A power-series solution representing the mode shape function of tall building is
used. Applying boundary conditions yields the boundary value problem; the frequency equation is established and solved through a numerical process to determine the natural frequencies. Computer program has been developed in Matlab (R2009b, Version 7.9.0.529, Mathworks Inc., California, USA). A numerical example has been solved to demonstrate the reliability of this method. The results of the
proposed mathematical model give a good understanding of the structure
Key Words
free vibration; framed tube; shear core; belt truss; outrigger system; variable cross section
Address
Mohammad Reza Jahanshahia and Reza Rahgozar: Department of Civil Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
Abstract
This study presents dynamic analysis of laminated beams traversed by moving loads using a multilayered beam element based on the first-order shear deformation theory. The present element consists of N layers with different thickness and material property, and has (3N + 7) degrees of freedom corresponding three axial, four transversal, and 3N rotational displacements. Delamination and interfacial
slip are not allowed. Comparisons with analytical and/or numerical results available in literature for some
illustrative examples are made. Numerical results for natural frequencies, deflections and stresses of laminated beams are given to explain the effect of load speed, lamina layup, and boundary conditions.
Key Words
moving loads; laminated beams; multilayered beam element; first-order shear deformation theory; finite element method
Address
Volkan Kahya: Department of Civil Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey
Abstract
In today\'s online social structure, people with electronic devices or network have been closely related to whether any of the activities, work, school, etc., is related to electronic devices, intelligent robot, and network control. The best mobility and the first rich media of these products as smart phones, smart phones rise rapidly in recent years, high speed processing performance and high free way to install software, deeply loved by many business people. However, not only for smart phone business aspects of the use, but also can engage in education of the teachers or the students are learning a great help. This study construct OCR-assisted learning software written by the JAVA made, and the installation is provided by the Android mobile phone users.
Key Words
smart phone; mandarin study; optical character recognition; fuzzy lyapunov; artificial intelligence
Address
Bih-Yaw Shih, Chen-Yuan Chen and Wei-Lun Su: Department and Graduate School of Computer Science, National Pingtung University of Education, No. 4-18, Ming Shen Rd., Pingtung 90003, Taiwan
