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CONTENTS
Volume 2, Number 2, June 1994
 

Abstract
A vector algorithm for calculating the stiffness matrices of reinforced concrete shell elements is presented. The algorithm is based on establishing vector lengths equal to the number of elements. The computational efficiency of the proposed algorithm is assessed on a Cray Y-MP supercomputer. It is shown that the vector algorithm achieves scalar-to-vector speedup of 1.7 to 7.6 on three moderate sized inelastic problems.

Key Words
vector algorithm; stiffness matrix; inelastic finite element analysis; cray Y-MP; supercomputer.

Address
Department of Ocean Civil Engineering, Cheju National Univ., Cheju 690-756, Korea
Center for Nuclear Power Plant Structures, Equipment and Piping, North Carolina State University, Raleigh, NC 27695-7908, U.S.A.

Abstract
In this paper, the effect of material elasticity was evaluated through a simple model as proposed by Wang and Yu (1991), for yield mechanisms of a cantilever beam under tip pulse loading. The beam was assumed rigid-perfectly plastic but instead of the usual fully clamped constraints at its root, an elastic-perfectly plastic rotational spring was introduced there so the system had a certain capacity to absorb elastic energy. Compared with a rigid-perfectly plastic beam without a spring root, the present beam-spring model showed differences in the initial plastic hinge position and the minimum magnitude of the dynamic force needed to produce a plastic failure. It was also shown that various failure responses may happen while the hinge travels along the beam segment towards the root, rather than a unique response mode as in a rigid perfectly plastic analysis.

Key Words
pipe whip; plastic hinge; impact; elasticity.

Address
School of Mechanical and Production Engineering, Nanyang Technological University, Singapore 2263, Singapore

Abstract
A general approach to the dynamic time-history analysis of the reactor core is presented in this paper as a part of the fuel assembly qualification program. Several detailed core models are set up to reflect the placement of the fuel assemblies within the core shroud. Peak horizontal responses are obtained for each model for the motions induced form earthquake. The dynamic responses such as fuel assembly deflected shapes and spacer grid impact loads are carefully investigated. Also, the sensitivity responses are obtained for the earthquake motions and the fuel assembly non-linear response characteristics are discussed.

Key Words
reactor internals; reactor core; fuel assembly; pressurized water reactor; seismic behavior; operating basis earthquake; safe shutdown earthquake; spacer grid.

Address
Power Reactor Mechanical Engineering, Korea Atomic Energy Research Institute 150 Dukjin-dong, Yusung-ku, Taejon 302-353, Korea
Department of Mechanical Engineering, Chonnam National University
Yongbong-dong 300, Puk-gu, Kwangju 500-757, Korea

Abstract
The objective of this study was to develop a simple and efficient numerical modeling technique for dynamic crack propagation using the finite element method. The study focused on the analysis of a rapidly propagation crack in an elastic body. As already known, discrete crack tip advance with the stationary node procedure results in spurious oscillation in the calculated energy terms. To reduce the spurious oscillation, a simple and efficient moving node procedure is proposed. The procedure does require neither remeshing the discretization nor distorting the original mesh. Two different central difference schemes are also evaluated and compared for dynamic crack propagation problem.

Key Words
finite element method; crack propagation; dynamic fracture.

Address
Mechanical Engineering Department, Naval Postgraduate School, Monterey, CA93943, U.S.A.

Abstract
In this paper a spline function solution for the ultimate strength of steel members and member structures is derived based on total Lagrangian formulation. The displacements of members along longitudinal and transverse directions are interpolated by one-order B spline functions and three-order hybrid spline functions respectively. Equilibrium equations are established according to the principle of virtual work. All initial imperfections of members and effects of loading, unloading and reloading of material are taken into account. The influence of the instability of members on structural behavior analyze the elasto-plastic large deflection problems of planar steel member and member structures.

Key Words
member structures; spline function solution; ultimate strength.

Address
College of Structural Engineering, Tongji University, Shanghai, China

Abstract
Presented in this paper is the rigorous analysis for the determination of effective flange width for composite beams. To make the solution suitable for routine design, formulas and tables for determining effective flange width for varying load types and geometric shapes are suggested. A variety of effective flange width problems for simple and continuous T-and I-beams can be solved by these tables and formulas. Although they are derived for T- and I-beams with symmetrical shapes, flanges and loads, they can be applied for non-symmetrical cases. Typical numerical examples are given to show how to use the formulas and tables; and their validity and accuracy are assessed by comparison with other known results that are based on the American Codes AISC, AASHTO and ACI.

Key Words
flange width; composite; design; codes; plates; T-beam; I-beam.

Address
Civil Engineering Department, University of Alabama, Birmingham, U.S.A.
Civil Engineering Department, University of Detroit Mercy, Detroit Michigan 48221, U.S.A.

Abstract
Responses of asymmetrical multistorey buildings to earthquakes are obtained by quasi-static code approach and real time dynamic analysis, using two different structural models. In the first model, all vertical members are assumed to be restrained at the slab levels and hence their end rotations, about horizontal axes, are taken as zero. In the second model this restriction is removed and the rotation is assumed to be proportional to the lateral stiffness of the member. A simple microcomputer based procedure is used in the analyses, by both models. Numerical examples are presented where results obtained from both the models are given. Effects of modelling on the response of three buildings, each with a different type and degree of asymmetry, are studied. Results for deflections and shear forces are presented and the effects of the type of model on the response are discussed.

Key Words
asymmetry; multistorey building; torsional coupling; core; twisting; earthquake loads; quasi-static method; dynamic analysis; modelling; degrees of freedom.

Address
School of Civil Engineering, Queensland University of Technology, Brisbane, Queensland 4001, Australia


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