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Volume 12, Number 4, October 2001

The paper deals with preventing the collapse of deck structures of skew and curved bridges
during earthquakes, by the means of supporting the bridges by rubber bearings and permitting pounding
between the decks and the abutments. Seismic response during pounding is characterized by various
phenomena, such as the caging of bridge decks between abutments during an earthquake or decks
popping out. These behaviors depend on only a small difference in seismic intensity. Regarding the global
characteristics of a seismic response, smaller clearance between a deck and its abutments results in smaller
impact damage of the abutments as well as lesser deformation of the rubber bearings. Similarly, smaller
clearance between a deck and the side blocks results in smaller damage. The stiffnesses of the bearings
and the stiffness ratio between them control the deck displacement. In short to medium length bridges,
zero clearance between a deck and the abutments or the deck and the side blocks is the most effective
way in preventing the deck from falling and limits the damage to the abutments or the side blocks.

Key Words
prevention of deck fall; skew bridge; curved bridge; seismic response with pounding.

Katsushi Ijima, Hiroyuki Obiya, Gunji Aramaki and Noriaki Kawasaki, Department of Civil Engineering, Saga University, 1 Honjo, Saga, Japan

Sandwich plates are widely used in lightweight design due to their high strength and stiffness
to weight ratio. Due to the heterogeneous structure of sandwich plates, they can exhibit local instabilities
(wrinkling), which lead to a sudden loss of stiffness in the structure. This paper presents an analytical
solution to the wrinkling problem of sandwich plates. The solution is based on the Rayleigh-Ritz method,
by assuming an appropriate deformation field. In contrast to the other approaches up to now, this model
takes arbitrary and different orthotropic face layers, finite core thickness and orthotropic core material into
account. This approach is the first to cover the wrinkling of unsymmetric sandwiches and sandwiches
composed of orthotropic FRP face layers, which are most common in advanced lightweight design. Despite
the generality of the solution, the computational effort is kept within bounds. The results have been
verified using other analytical solutions and unit cell 3D FE calculations.

Key Words
sandwich; instability; wrinkling; elastic foundation; shell; plate; buckling; orthotropy.

Walter K. Vonach and Franz G. Rammerstorfer, Institute of Lightweight Structures and Aerospace Engineering, Vienna University of Technology, Gusshausstrasse 27-29, A-1040 Wien, Austria

The excessive cracking of RC cantilever decks, which often requires special attention for structural
engineers, is studied using a three-dimensional crack analysis model. The model is based on a fracture
energy approach for analyzing cracks in concrete, and the numerical analysis is carried out using a
modified load control method. The problem of excessive cracking is then studied with four different span-ratios.
Based on the numerical results, the crack behavior with respect to the patterns of crack propagation,
dissipation of the fracture energy, and effects on the structural integrity are discussed. The mechanisms
which cause the excessive cracking are also explained.

Key Words
RC cantilever decks; 3-D crack analysis; fracture energy; load control.

Zihai Shi and Masaaki Nakano, Research and Development Center, Nippon Koei Co., Ltd., 2304 Inarihara, Kukizaki-machi, Inashiki-gun, Ibaraki 300-1259, Japan

Bolted connections are used commonly in the precast reinforced concrete structures. In such
structures, to perform structural analysis, behaviour of connections must be determined. In this study,
elastic rotation stiffness of semi-rigid bolted beam connections, applied in industrial precast structures, are
determined by finite element methods. The results obtained from numerical solutions are compared with
an experimental study carried out for the same connections. Furthermore, stress distributions of the
connection zone are determined and a reinforcement scheme is proposed. Thus, a more appropriate
reinforcement arrangement for the connection zone is enabled. The connection joint of the prefabricated
frame is described as rigid, hinged or elastic, and a static analysis of the frame system is performed for
each case. Values of bending moments and displacements obtained from the three solutions are compared
and the effects of elastic connection are discussed.

Key Words
prefabricated reinforced concrete; bolted connection; semi-rigid connection; elastic connection; elastic rotation stiffness.

E. Irtem and K. Turker, Department of Civil Engineering, Ballkesir University, Ballkesir 10100, Turkey

The characteristics of dynamic wheel loads of heavy vehicles running on bridge and rigid
surface are investigated by using three-dimensional analytical model. The simulated dynamic wheel loads
of vehicles are compared with the experimental results carried out by Road-Vehicles Research Institute of
Netherlands Organization for Applied Scientific Research (TNO) to verify the validity of the analytical
model. Also another comparison of the analytical result with the experimental one for Umeda Entrance
Bridge of Hanshin Expressway in Osaka, Japan, is presented in this study. The agreement between the
analytical and experimental results is satisfactory and encouraging the use of the analytical model in
practice. Parametric study shows that the dynamic increment factor (DIF) of the bridge and RMS values
of dynamic wheel loads are fluctuated according to vehicle speeds and vehicle types as well as roadway
roughness conditions. Moreover, there exist strong dominant frequency resemblance between bounce
motion of vehicle and bridge response as well as those relations between RMS values of dynamic wheel
loads and dynamic increment factor (DIF) of bridges.

Key Words
dynamic increment factor (DIF); dynamic wheel load; Power spectral density (PSD); Root mean square (RMS); three-dimensional dynamic analysis; traffic-induced vibration.

Mitsuo Kawatani, Department of Civil Engineering, Kobe University, 1-1 Rokkodai-Cho, Nada-gu, Kobe 657-8501, Japan
Chul-Woo Kim, Department of Civil Engineering, Pohang College, 55 Jukchun-Dong, Buk-gu, Pohang 791-711, Korea

An analytical model incorporating bending and shear behavior is presented to predict the
lateral loading characteristic for rectangular hollow columns. The moment-curvature relationship for the
rectangular hollow sections of a column is firstly determined. Then the nonlinear lateral load-displacement
relationship for the hollow column can be obtained accordingly. In this model, thirteen constitutive laws
for confined concrete and five approaches to estimate the shear capacity are used. A series of tests on 12
model hollow columns aimed at the seismic shear behavior are reported, and the test data are compared to
the analytical results. It is found that the analytical model reflects the experimental results rather closely.

Key Words
hollow bridge column; shear behavior; seismic behavior; confined concrete; ductility factor; load-displacement relationship.

Y. L . Mo and Chyuan-Hwan Jeng, Department of Civil and Environmental Engineering, University of Houston, Houston, Texas, U.S.A.
S.F. Perng, Department of Civil Engineering, National Kaohsiung Institute of Technology, Kaohsiung, Taiwan

In the design of industrial chimneys and towers, structural engineers must assume a level of
the inherent damping in the structures. In order to better estimate the dynamic response of those
structures, actual damping was measured from wind-induced vibration signals of chimneys and towers and
its characteristics with respect to the response levels, the structural systems, and the wind direction were
discussed. Damping ratio and natural frequency for three chimneys and two towers were calculated using
random decrement technique.

Key Words
damping; frequency; field measurement; random decrement technique; chimneys and towers; wind-induced vibration.

K.P. Cho and Y. Tamura, Department of Architectural Engineering, Tokyo Institute of Polytechnics, 1583, Iiyama, Atsugi, Kanagawa 243-0297, Japan
T. Itoh, Architectural Design Department, Tokyo Electric Power Services Co., Iino Bldg. 1-1, Uchisaiwai-Cho 2-Chome, Chiyoda-Ku, Tokyo 100-0011, Japan
M. Narikawa, Y. Uchikawa, I. Nishimura and Y. Ohshima, Architecture Group, Power Engineering R&D Center, Tokyo Electric Power Company
4-1 Egasaki-Cho, Tsurumi-Ku, Yokohama 230, Japan

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