Abstract
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.
Address
Katsushi Ijima, Hiroyuki Obiya, Gunji Aramaki and Noriaki Kawasaki, Department of Civil Engineering, Saga University, 1 Honjo, Saga, Japan
Abstract
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.
Address
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
Abstract
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.
Address
Zihai Shi and Masaaki Nakano, Research and Development Center, Nippon Koei Co., Ltd., 2304 Inarihara, Kukizaki-machi, Inashiki-gun, Ibaraki 300-1259, Japan
Abstract
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.
Abstract
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.
Address
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
Abstract
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.
Address
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
Abstract
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.
Address
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
