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Abstract
Analytical solutions and finite element results of laminated composite plates with smart
material layers embedded in them are presented in this study. The third-order plate theory of Reddy is
used to study vibration suppression characteristics. The analytical solution for simply supported boundary
conditions is based on the Navier solution procedure. The velocity feedback control is used. Parametric
effects of the position of the smart material layers, material properties, and control parameters on the
suppression time are investigated. It has been found that (a) the minimum vibration suppression time is
achieved by placing the smart material layers farthest from the neutral axis, (b) using thinner smart
material layers have better vibration attenuation characteristics, and, (c) the vibration suppression time is
larger for a lower value of the feedback control coefficient.

Key Words
analytical solutions; composite plates; finite element solutions; third-order plate theory; vibration control.

Address
J.N. Reddy and S. Krishnan, Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123, U.S.A.

Abstract
In this paper, experimental investigation into the behavior of reinforced concrete (RC)
columns tested under large lateral displacement with four different types of loading arrangements is
presented. Each loading arrangement has a different system for controlling the consistency of the loading
condition. One of the loading arrangements used three units of link mechanism to control the parallelism
of the top and bottom stub of column during testing, and the remaining employed eight hydraulic jacks
for the same purpose. The loading systems condition used in this investigation were similar to the actual
case in a moment-resisting frame where the tested column was displaced in a double curvature. Ten
model column specimens, divided into four series were prepared. Two columns were tested monotonically
until collapse, and unless failure took place at an earlier stage of loading, the remaining eight columns
were tested under cyclic loading. Test results indicated that the proposed system to keep the top and
bottom stubs parallel during testing performed well.

Key Words
complete collapse; constant axial load; lateral load; lateral displacement; loading arrangement; parallel keeping system; reinforced concrete column.

Address
Abdullah and Katsuki Takiguchi, Department of Mechanical and Environmental Informatics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan

Abstract
This note presents the main results of an experimental investigation into the mechanical
behaviour of a composite sandwich conceived as a lightweight material for naval engineering applications.
The sandwich structure is formed by a three-dimensional glass fibre/polymer matrix fabric with transverse
piles interconnecting the skins; the core is filled with a polymer matrix/glass microspheres syntactic foam;
additional Glass Fibre Reinforced Plastics extra-skins are laminated on the external facings of the filled
fabric. The main features of the experimental tests on syntactic foam, skins and sandwich panels are
presented and discussed, with focus on both in-plane and out-of-plane responses. This work is part of a
broader research investigation aimed at a complete characterisation, both experimental and numerical, of
the complex mechanical behaviour of this composite sandwich.

Key Words
mechanical tests; syntactic foam; glass fibre; composite sandwich.

Address
Enrico Papa and Alberto Corigliano, Dipartimento di Ingegneria Strutturale, Facolta di Ingegneria Leonardo, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
Egidio Rizzi, Dipartimento di Ingegneria Civile e Ambientale, Facolta di Ingegneria di Taranto, Politecnico di Bari, Via Orabona 4, I-70125 Bari, Italy

Abstract
This paper presents an experimental modal analysis of perforated rectangular plates in air or
in contact with water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to
diameter) 2.125, 2.500, 3.000 and 3.750. The plate was clamped along the plate edges by a number of
bolts and nuts. The natural frequencies of the perforated plates in air were obtained by the analytical
method based on the relation between the reference kinetic and maximum potential energies and
compared with the experimental results. Good agreement between the results was found for the natural
frequencies of the perforated plates in air. Additionally, it was empirically found that the natural
frequencies of the perforated plate in air increase with an increase of P/D, on the other hand, the natural
frequencies of the perforated plate in contact with water decrease with an increase of P/D.

Key Words
experimental modal analysis; fluid-structure interaction; perforated plate; added mass; clamped boundary condition; rectangular plate; triangular hole pattern; natural frequency; free vibration.

Address
Kyeong-Hoon Jeong, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Taejon 305-600, Korea
Byung-Ki Ahn and Seong-Cheol Lee, Department of Mechanical Engineering, Chonbuk National University, Chonju, Chonbuk 560-756, Korea

Abstract
Four finite element (FE) models are examined to find the one that best estimates moment-rotation
characteristics of top- and seat-angle with double web-angle connections. To efficiently simulate
the real behavior of connections, finite element analyses are performed with following considerations: 1) all
components of connection (beam, column, angles and bolts) are discretized by eight-node solid elements;
2) shapes of bolt shank, head, and nut are precisely taken into account in modeling; and 3) contact
surface algorithm is applied as boundary condition. To improve accuracy in predicting moment-rotation
behavior of a connection, bolt pretension is introduced before the corresponding connection moment being
surcharged. The experimental results are used to investigate the applicability of FE method and to check
the performance of three-parameter power model by making comparison among their moment-rotation
behaviors and by assessment of deformation and stress distribution patterns at the final stage of loading.
This research exposes two important features: (1) the FE method has tremendous potential for connection
modeling for both monotonic and cyclic loading; and (2) the power model is able to predict moment-rotation
characteristics of semi-rigid connections with acceptable accuracy.

Key Words
semi-rigid connection; moment-rotation behavior; connection stiffness and strength; monotonic loading; finite element method.

Address
N. Kishi, A. Ahmed and N. Yabuki, Department of Civil Engineering, Muroran Institute of Technology, Muroran 050-8585, Japan
W.F. Chen, College of Engineering, University of Hawaii, Manoa, Honolulu, HI 96822, U.S.A.

Abstract
In this paper, an asymptotic two-scale method is developed for solving vibration problem of
long periodic structures. Such eigenmodes appear as a slow modulations of a periodic one. For those, the
present method splits the vibration problem into two small problems at each order. The first one is a
periodic problem and is posed on a few basic cells. The second is an amplitude equation to be satisfied
by the envelope of the eigenmode. In this way, one can avoid the discretisation of the whole structure.
Applying the Floquet method, the boundary conditions of the global problem are determined for any order
of the asymptotic expansions.

Key Words
vibrations; periodic structures; asymptotic two-scale method; boundary layer; Floquet theory.

Address
E.M. Daya and M. Potier-Ferry, Laboratoire de Physique et Mecanique des Materiaux UMR CNRS 7554, Institut Superieur de Genie Mecanique et Productique Universite de Metz, Ile du Saulcy, 57045 Metz cedex 01, France

Abstract
The three-dimensional behavior of confined concrete was investigated, including strength
enhancement due to triaxial compressive stresses, lateral expansion, compression softening, cover spalling
and post-peak ductility. A finite element program based on a nonlinear elasticity methodology was
employed to evaluate the ability to model triaxial behavior of reinforced concrete (RC) by combining
constitutive models proposed by several researchers. The capability of compression field based models to
reproduce the softening behavior of lightly cracked confined concrete was also investigated. Data from
tested specimens were used to evaluate the validity of the formulations. Good agreement with the
experimental results was obtained.

Key Words
nonlinear; finite element; analysis; reinforced concrete; confinement; lateral expansion; columns.

Address
E. Montoya, F.J. Vecchio and S.A. Sheikh, Department of Civil Engineering, University of Toronto, Toronto, Canada

Abstract
Current seismic design provisions allow structures to deform into inelastic range during
design level earthquakes since the chance to meet such event is quite rare. For this purpose, design base
shear is defined in current seismic design provisions as the value of elastic seismic shear force divided by
strength reduction factor, R (

Key Words
P-D effect; strength reduction factor; ductility factor.

Address
Sang Whan Han, Oh-Sung Kwon and Li-Hyung Lee, Department of Architectural Engineering, Hanyang University, Seoul 133-791, Korea

Abstract
Transient and quasi-steady-state vertical vibrations of a multi-span beam steel bridge located
on a single-track railway line are considered, induced by a superfast passenger train, moving at speed
120-360 km/h. Matrix dynamic equations of motion of a simplified model of the system are formulated
partly in the implicit form. A recurrent-iterative algorithm for solving these equations is presented.
Excessive vibrations of the system in the resonant zones are reduced effectively with passive dynamic
absorbers, tuned to the first mode of a single bridge span. The dynamic analysis has been performed for a
series of types of bridges with span lengths of 10 to 30 m, and with parameters closed to multi-span
beam railway bridges erected in the second half of the 20 th century.

Key Words
railway bridge; multi-span bridge; beam steel bridge; superfast train; moving load; transient vibrations; quasi-steady-state vibrations; passive dynamic absorbers; vibration control.

Address
M. Klasztorny, Institute of Mechanics and Design, Warsaw University of Technology, Warsaw 02524, Poland

Abstract
The postbuckling behaviour of thin plates is an important phenomenon in the design of thin
plated structures. In reality plates possess small imperfections and the behaviour of such imperfect plates
is of great interest. To numerically study the postbuckling behaviour of imperfect plates explicit
incremental or secant matrices have been presented in this paper. These matrices can be used in
combination with any thin plate element. The secant matrices are shown to be very accurate in tracing the
postbuckling behaviour of thin plates.

Key Words
postbuckling behaviour, imperfect plates, nonlinear finite element analysis, secant or incremental matrices.

Address
S. Arul Jayachandran, Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai-600 113, India
S. Gopalakrishnan, Indian Institute of Science, Bangalore-560 012, India
R. Narayanan, Structural Engineering Research Centre, CSIR Campus, Taramani, Chennai-600 113, India

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