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CONTENTS
Volume 3, Number 3, May 1995
 

Abstract
At present Level 2 and importance sampling methods are the main tools used to estimate reliability of structural systems. But sometimes application of these techniques to realistic problems involves certain difficulties. In order to overcome the difficulties it is suggested to use Monte Carlo simulation in combination with two other techniques-extreme value and tail entropy approximations; an appropriate Pearson\'s curve is fit to represent simulation results. On the basis of this approach an algorithm and computer program for structural reliability estimation are developed, A number of specially chosen numerical examples are considered with the aim of checking the accuracy of the approach and comparing it with the Level 2 and importance sampling methods. The field of application of the approach is revealed.

Key Words
STRUCTURAL RELIABILITY, MONTE CARLO SIMULATION, PEARSONS CURVES, EXTREME VALUE APPROXIMATION, TAIL ENTROPY APPROXIMATION

Address
KRAKOVSKI MB, UNIV ULSAN,DEPT NAVAL ARCHITECTURE,ULSAN 680749,SOUTH KOREA
PERMANENTLY RES INST CONCRETE & REINFORCED CONCRE,MOSCOW 109428,RUSSIA

Abstract
For non-classically damped structures subjected to evolutionary random seismic excitations, the non-stationary random responses are computed by means of a high precision direct (HPD) integration scheme combined with the pseudo excitation method. Only real modes are used, so that the reduced equations of motion remain coupled for such non-classically damped structures, In the given examples, the efficiency of this method is compared with that of the Newmark method.

Key Words
NONSTATIONARY RANDOM DIRECT INTEGRATION DAMPING

Address
LIN JH, DALIAN UNIV TECHNOL,ENGN MECH RES INST,DALIAN 116023,PEOPLES R CHINA
SHANGHAI JIAO TONG UNIV,DEPT ENGN MECH,SHANGHAI 200030,PEOPLES R CHINA
UNIV WALES COLL CARDIFF,CARDIFF SCH ENGN,DIV STRUCT ENGN,CARDIFF CF2 1XH,S GLAM,WALES

Abstract
The parametric instability behaviour of a plate subjected to localized in-plane compressive or tensile periodic edge loading is studied, considering the effects of damping into the system. Different edge loading cases have been considered. Damping has been introduced in the form of proportional damping, Dynamic instability behaviour under compressive or tensile periodic edge loading shows that the instability regions are influenced by the load band width and its location on the edge, The effects of damping on the instability regions show that there is a critical value of dynamic load factor beyond which the plate becomes dynamically unstable. The critical dynamic load factor increases as damping increases. Damping generally reduces the widths of the instability regions.


Key Words
PLATE, EDGE LOADING, COMPRESSION, TENSION, DAMPING, PARAMETRIC INSTABILITY

Address
DEOLASI PJ, INDIAN INST TECHNOL,DEPT AEROSP ENGN,KHARAGPUR 721302,W BENGAL,INDIA

Abstract
A combination of Riccati transfer matrix method and finite element method is proposed for obtaining vibration frequencies of structures. This method reduces the propagation of round-off errors produced in the standard transfer matrix method and finds out the values of the frequency by Newton-Raphson method, By this technique, the number of nodes required in the regular finite element method is reduced and therefore a microcomputer may be used. Besides, no plotting of the value of the determinant versus assumed frequency is necessary, As the application of this method, some numerical examples are presented to demonstrate the accuracy as well as the capability of the proposed method for the vibration of structures.

Key Words
FINITE ELEMENT, TRANSFER MATRIX, RICCATI TRANSFORMATION, VIBRATION, NEWTON-RAPHSON METHOD

Address
XUE HY, SUZHOU UNIV,DEPT PHYS,SUZHOU 215006,PEOPLES R CHINA

Abstract
The paper considers aspects of the energy dissipation response of selected realistic forms of torsionally balanced and torsionally unbalanced building systems, responding to an ensemble of strong-motion earthquake records. Focus is placed on the proportion of the input seismic energy which is dissipated hysteretically, and the distribution of this energy amongst the various lateral load-resisting structural elements. Systems considered comprise those in which torsional effects are discounted in the design, and systems designed for torsion by typical code-defined procedures as incorporated in the New Zealand seismic standard. It is concluded that torsional response has a fundamentally significant influence on the energy dissipation demand of the critical edge elements, and that therefore the allocation of appropriate levels of yielding strength to these elements is a paramount design consideration. Finally, it is suggested that energy-based response parameters be developed in order to assist evaluations of the effectiveness of code torsional provisions in controlling damage to key structural elements in severe earthquakes.


Key Words
ENERGY DISSIPATION, HYSTERETIC BEHAVIOR, SEISMIC RESPONSE, TORSIONAL DESIGN

Address
CORRENZA JC, UNIV MELBOURNE,DEPT CIVIL & ENVIRONM ENGN,PARKVILLE,VIC 3052,AUSTRALIA
UNIV COLL LONDON,DEPT CIVIL & ENVIRONM ENGN,LONDON WC1E 6BT,ENGLAND

Abstract
Stochastic response of systems to random excitation can be estimated by direct integration methods in the time domain such as the stochastic central difference method (SCDM). In this paper, the SCDM is applied to compute the variance and covariance in response of linear and nonlinear structures subjected to random excitation. The accuracy of the SCDM is assessed using two-DOF systems with both deterministic and random material properties excited by white noise. For the former case, closed-form solutions can be obtained. Numerical results also are presented for a simply supported geometrically nonlinear beam. The stiffness of this beam is modeled as a random field, and the beam is idealized by the stochastic finite element method. A perturbation technique is applied to formulate the equations of motion of the system, and the dynamic structural response statistics are obtained in a time domain analysis. The effect of variations in structural parameters and the numerical stability of the SCDM also are examined.

Key Words
COMPUTATIONAL MECHANICS, DYNAMICS, PROBABILITY, RANDOM VIBRATION, STATISTICS, STRUCTURAL ENGINEERING

Address
JOHNS HOPKINS UNIV,DEPT CIVIL ENGN,BALTIMORE,MD 21218
UNIV COLORADO,SCH ENGN & APPL SCI,BOULDER,CO 80309
CONNECTICUT DEPT TRANSPORTAT,MAPLE HILL,CT 06111

Abstract
A finite element algorithm for consideration of contact constraints is presented. It is characterized by introducing the geometric constraints, resulting from contact conditions, directly into the algebraic system of equations for the incremental displacements of an incremental iterative solution procedure. The usefulness of the proposed algorithm for efficient solutions of contact problems involving large displacements and large strains is demonstrated in the numerical investigation.

Key Words
FINITE ELEMENTS, CONTACT PROBLEM, FRICTION, GEOMETRIC CONSTRAINTS, LARGE DISPLACEMENTS, LARGE STRAINS

Address
LIU CH, VIENNA TECH UNIV,INST STRENGTH MAT,KARLSPL 13,A-1040 VIENNA,AUSTRIA


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