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CONTENTS
Volume 6, Number 5, July 1998
 

Abstract
The first and second moments of response variables for SDOF systems with hysteretic nonlinearity are obtained by a direct linearization procedure. This adaptation in the implementation of well-known statistical linearization methods, provides concise, model-independent linearization coefficients that are well-suited for numerical solution. The method may be applied to systems which incorporate any hysteresis model governed by a differential constitutive equation, and may be used for zero or non-zero mean random vibration. The implementation eliminates the effort of analytically deriving specific linearization coefficients for new hysteresis models. In doing so, the procedure of stochastic analysis is made independent from the task of physical modeling of hysteretic systems. In this study, systems with three different hysteresis models are analyzed under various zero and non-zero mean Gaussian White noise inputs. Results are shown to be in agreement with previous Linearization studies and Monte Carlo Simulation.

Key Words
linearization, hysteresis, asymmetric models, random vibrations

Address
Dobson S, Worcester Polytech Inst, Stochast Mech & Anal Res Grp, Worcester, MA 01609 USA
Worcester Polytech Inst, Stochast Mech & Anal Res Grp, Worcester, MA 01609 USA

Abstract
Standard finite element wave propagation codes are useful for determining stresses caused by the impact of one body with another; however, their applicability to a laminated system such as architectural laminated glass is limited because the important interlayer delamination process caused by impact loading is difficult to model. This paper presents a method that allows traditional wave propagation codes to model the interlayer debonding of laminated architectural glass subject to low velocity, small missile impact such as that which occurs in severe windstorms. The method can be extended to any multilayered medium with adhesive bonding between the layers. Computational results of concern to architectural glazing designers are presented.

Key Words
debonding, impact, laminated glass, fracture, finite element method

Address
Flocker FW, Stress Engn Serv, Houston, TX USA
Univ Missouri, Dept Mech & Aerosp Engn & Engn Mech, Rolla, MO 65409 USA

Abstract
A relatively simple two-dimensional multilayered shell model is presented for predicting both global quantities and stress distributions across the thickness of multilayered thick shells, that is based on a third-order zig-zag approach. As for any zig-zag model, the layerwise kinematics is accounted for, with the stress continuity conditions at interfaces met a priori. Moreover, the shell model satisfies the zero transverse shear stress conditions at the upper and lower free surfaces of the shell, irrespective of the lay-up. By changing the parameters in the displacement model, some higher order shell models are obtained as particular cases. Although it potentially has a wide range of validity, application is limited to cylindrical shell panels in cylindrical bending, a lot of solutions of two-dimensional models based on rather different simplyfying assumptions and the exact three-dimensional elasticity solution being available for comparisons for this benchmark problem. The numerical investigation performed by the present shell model and by the shell models derived from it illustrates the effects of transverse shear modeling and the range of applicability of the simplyfying assumptions introduced. The implications of retaining only selected terms depending on the radius-to-thickness ratio are focused by comparing the present solutions to the exact one and to other two-dimensional solutions in literature based on rather different simplyfying assumptions.

Key Words
laminated shells modeling, layer-wise theories, stress analysis

Address
Icardi U, Politecn Turin, Dipartimento Ingn Aeronaut & Spaziale, Corso Duca Abruzzi 24, I-10129 Turin, Italy
Politecn Turin, Dipartimento Ingn Aeronaut & Spaziale, I-10129 Turin, Italy

Abstract
This paper describes an exact method of analysis for natural vibration of diagonal networks by considering an equivalent cyclic periodic structure and adopting the double U-transformation technique. Both a lumped mass system and a distributed mass system are considered to investigate the diagonal networks. The exact solution for the frequency equations and the natural modes of the networks can be derived. As numerical examples, square diagonal cable networks with different meshes are worked out.


Key Words
diagonal network, natural vibration, the U-transformation technique, analytical method, exact solution

Address
Chai WS, GuangDong Univ Technol, Dept Civil Engn, Dongfengdong Rd, Guangzhou 510090, Peoples R China
GuangDong Univ Technol, Dept Civil Engn, Guangzhou 510090, Peoples R China
Univ Hong Kong, Dept Civil & Struct Engn, Hong Kong, Hong Kong

Abstract
Generalised plane strain solution is presented for simply supported, angle-ply laminated hybrid plate under cylindrical bending. The arbitrary constants in the general solution of the governing differential equations are obtained from the boundary and interface conditions. The response of hybrid plates to sinusoidal loads is obtained to illustrate the effect of the thickness parameter and the ply-angle. The classical lamination theory and the first order shear deformation theory are also assessed.


Key Words
piezothermoelectric response, cylindrical bending, angle-ply plate, laminated plate, simply supported plate

Address
Dube GP, Indian Inst Technol, Dept Appl Mech, New Delhi 110016, India
Indian Inst Technol, Dept Appl Mech, New Delhi 110016, India

Abstract
Space truss structures may be fabricated in any of several common grid configurations. With different configurations, the truss performance varies considerably affecting both its competitiveness and suitability for specific applications. The work presented in this paper is an assessment of the most commonly adopted truss configurations and their effect on truss characteristics such as the stiffness/weight value, member stress distribution, number of joints and members, degree of redundancy and cost. The study is parametric and covers wide variations of truss aspect ratios, boundary conditions and span/depth ratios. The results of this study could be of significant value to the design of space truss structures.

Key Words
space trusses, design

Address
El-Sheikh A, Univ Dundee, Dept Civil Engn, Dundee DD1 4HN, Scotland
Univ Dundee, Dept Civil Engn, Dundee DD1 4HN, Scotland

Abstract
The reliability of antenna tower designed for a n-year design wind speed is determined by considering the variability of the strength of the component members and of the mean wind speed. For obtaining the n-year design wind speed, maximum annual wind speed is assumed to follow Gumbel Type-1 distribution. Following this distribution of the wind speed, the mean and standard deviation of stresses in each component member are worked out. The variability of the strength of members is defined by means of the nominal strength and a coefficient of variation. The probability of failure of the critical members of tower is determined by the first order second moment method (FOSM) of reliability analysis. Using the above method, the reliability against allowable stress failure of the critical members as well as the system reliabilities for a 75 m tall antenna tower, designed for n-year design wind speed, are presented.

Key Words
microwave towers, reliability, system reliability, extreme wind, first order second moment method (FOSM)

Address
Deoliya R, Struct Engn Res Ctr, Gaziabad 201001, Uttar Pradesh, India
Struct Engn Res Ctr, Gaziabad 201001, Uttar Pradesh, India
Indian Inst Technol, Dept Civil Engn, New Delhi 110016, India

Abstract
Testing of steel roof purlins is usually performed on full scale models in large vacuum test rigs. To undertake a comparison between web cleat connected purlins and flange bolted purlins a series of tests were performed on a 1:4 small scale model vacuum test rig. Various modelling issues need to be addressed to ensure reasonable comparison with actual constructed roof framing methods but still be suitable for an economical comparison between the connection methods. Model test results were supported by, and found to be in reasonable agreement with, deflection predictions from computer models based on finite element methods. This paper discusses the testing methods adopted and the value of small scale model testing programs as a means of obtaining comparisons between framing options.

Key Words
cleats, connection, flange, purlins, roofs, scale model, steel, tests

Address
Urquhart SM, Univ Western Australia, Nedlands, WA 6009, Australia
Univ Western Australia, Nedlands, WA 6009, Australia


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