Applications of membrane mechanisms are widely found in nano-devices and nano-sensor technologies nowadays. An alternative approach for large deflection analysis of the orthotropic, elliptic membranes . subject to gravitational, uniform pressures often found in nano-sensors . is described in this paper. The material properties of membranes are assumed to be orthogonally isotropic and linearly elastic, while the principal directions of elasticity are parallel to the coordinate axes. Formulating the potential energy functional of the orthotropic, elliptic membranes involves the strain energy that is attributed to inplane stress resultant and the potential energy due to applied pressures. In the solution method, Rayleigh-Ritz method can be used successfully to minimize the resulting total potential energy generated. The set
of equilibrium equations was solved subsequently by Newton-Raphson. The unparalleled model formulation capable of analyzing the large deflections of both circular and elliptic membranes is verified by making numerical comparisons with existing results of circular membranes as well as finite element solutions. The results are found in excellent agreements at all cases. Then, the parametric investigations are given to delineate the impacts of the aspect ratios and orthotropic elasticity on large static tensions and deformations of the orthotropic, elliptic membranes.
membrane structures; elliptic membranes; circular membranes; nonlinear static analysis; large deflections; large static tension; Rayleigh-Ritz method; energy minimization.
Somchai Chucheepsakul: Department of Civil Engineering, King Mongkut
A comprehensive investigation of the stochastic response of an isolated cable-stayed bridge subjected to spatially varying earthquake ground motion is performed. In this study, the Jindo Bridge built in South Korea is chosen as a numerical example. The bridge deck is assumed to be continuous from one end to the other end. The vertical movement of the stiffening girder is restrained and freedom of rotational movement on the transverse axis is provided for all piers and abutments. The longitudinal restraint is provided at the mainland pier. The A-frame towers are fixed at the base. To implement the base isolation procedure, the double concave friction pendulum bearings are placed at each of the four support points of the deck. Thus, the deck of the cable-stayed bridge is isolated from the towers using the double concave friction pendulum bearings which are sliding devices that utilize two spherical concave surfaces. The spatially varying earthquake ground motion is characterized by the incoherence and wavepassage effects. Mean of maximum response values obtained from the spatially varying earthquake ground motion case are compared for the isolated and non-isolated bridge models. It is pointed out that the base isolation of the considered cable-stayed bridge model subjected to the spatially varying earthquake ground motion significantly underestimates the deck and the tower responses.
spatially varying ground motion; wave-passage effect; incoherence effect; base isolation; isolated bridge; cable-stayed bridge; double concave friction pendulum.
Sevket Ates: Department of Civil Engineering, Karadeniz Technical University, Trabzon, 61080, Turkey
Kurtulus Soyluk: Department of Civil Engineering, Gazi University, Maltepe, Ankara, 06570, Turkey
A. Aydin Dumanoglu: Department of Civil Engineering, Karadeniz Technical University, Trabzon, 61080, Turkey
Alemdar Bayraktar: Department of Civil Engineering, Karadeniz Technical University, Trabzon, 61080, Turkey
An exact solution is obtained for forced torsional vibration of a finite class 622 piezoelectric hollow cylinder with free-free ends subjected to dynamic shearing stress and time dependent electric potential at both internal and external surfaces. The solution is first expanded in axial direction with trigonometric series and the governing equations for the new variables about radial coordinate r and time t are derived with the aid of Fourier series expansion technique. By means of the superposition method and the separation of variables technique, the solution for torsional vibration is finally obtained. Natural frequencies and the transient torsional responses for finite class 622 piezoelectric hollow cylinder with free-free ends are computed and illustrated.
exact solution; torsional vibration; finite hollow cylinder; piezoelectric.
H. M. Wang: Department of Mechanics, Zhejiang University, Hangzhou 310027, P. R. China
C. B. Liu and H. J. Ding: Department of Civil Engineering, Zhejiang University, Hangzhou 310027, P. R. China
The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann\'s series. In order to implement this approach, the special recurrent relations for
half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading
(degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the
opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.
boundary element method; buried structures; half space; openings; stress concentration.
Karinski Y.S., Yankelevsky D.Z. and Antes M.Y.: National Building Research Institute, Faculty of Civil and Environmental Engineering, Technion - IIT, Haifa, 32000, Israel
This paper summarizes an experimental and analytical study on the seismic behavior of high strength reinforced concrete columns under cyclic loading. In total six cantilever columns with different sizes and concrete compressive strengths were tested. Three columns, small size, had a 325 x 325 mm cross section and the three other columns, medium size, were 520 x 520 mm. Concrete compressive strength was 80, 130 and 180 MPa. All specimens were designed in accordance with the Japanese design guidelines. The tests demonstrated that, for specimens made of 180 MPa concrete compressive strength, spalling of cover concrete was very brittle followed by a significant decrease in strength. Curvature was much important for the small size than for the medium size columns. Concrete compressive strength had
no effect on the curvature distribution for a drift varying between −2% and +2%. However, it had an effect on the drift corresponding to the peak moment and on the equivalent viscous damping variation. Simple equations are proposed for 1) evaluating the concrete Young\'s modulus for high strength concrete and for 2) evaluating the moment-drift envelope curves for the medium size columns knowing that of the
small size columns. Experimental moment-drift and axial strain-drift histories were well predicted using a
fiber model developed by the authors.
column; high strength concrete; performance; scale effect; damping factor; curvature; capacity; damage.
Hakim Bechtoula: National Earthquake Engineering Center, C.G.S 01 Rue Kaddour Rahim, BP252 Hussein Dey, Alger, Algeria
Susumu Kono and Fumio Watanabe: Department of Architecture and Architectural Engineering, Kyoto University, Nishikyo, Kyoto 6158540, Japan
The present problem is concerned with the study of deformation of micropolar thermoelastic medium with voids under the influence of various sources acting on the plane surface. The analytic expressions of displacement components, force stress, couple stress, change in volume fraction field and temperature distribution are obtained in the transformed domain for Lord-Shulman (L-S) theory of
thermoelasticity after applying the integral transforms. A numerical inversion technique has been applied to obtain the solution in the physical domain. The numerical results are presented graphically. Some useful particular cases have also been deduced.
micropolar thermoelastic solid; voids; couple stress; thermoelasticity; integral transform.
Rajneesh Kumar: Department of Mathematics, Kurukshetra University, Kurukshetra, Haryana, India
Praveen Ailawalia: Department of Mathematics, M.M. Engineering College, Maharishi Markandeshwar University, Mullana, Ambala, Haryana, India
The problem of estimating the dynamic response of a distributed parameter system excited by a moving vehicle with random initial velocity and random vehicle body mass is investigated. By adopting the Galerkin\'s method and modal analysis, a set of approximate governing equations of motion
possessing time-dependent uncertain coefficients and forcing function is obtained, and then the dynamic response of the coupled system can be calculated in deterministic sense. The statistical characteristics of the responses of the system are computed by using improved perturbation approach with respect to mean value. This method is simple and useful to gather the stochastic structural response due to the vehicle passenger-bridge interaction. Furthermore, some of the statistical numerical results calculated from the
perturbation technique are checked by Monte Carlo simulation.
T-P. Chang: Department of Construction Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan, ROC
M-F. Liu: Department of Applied Mathematics, I-Shou University, Kaohsiung, Taiwan, ROC
H-W. O: Department of Construction Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan, ROC
Hyuk Chun Noh: Department of Civil and Environmental Engineering, Sejong University, Seoul, Korea
Phill Seung Lee: Department of Ocean Systems Engineering, Korea Advanced Institute of Science and Technology,
Chang Koon Choi: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea