Authors:Miklós Ifj. Ivanyi, Radu Bancila and Miklós Ivany
Nowadays the most modern and economical bridges are designed as composite structures with orthotropic plates. In a traditionally designed composite bridge the trapezoidal, longitudinal stiffener is attached, welded to the cross girder web and to the bottom flange of the main girder. However in recent composite bridges with orthotropic plates designed by the UVATERV Co. the cross girder web and the trapezoidal, longitudinal stiffeners are not connected. This is a very important improvement, since in this way the amount of cutting and welding work can be reduced, however more importantly there is no need to consider the fatigue of the welds between the longitudinal stiffener and the cross girder web. On the other hand the disadvantage of this design that the plate-buckling phenomenon of the free edge must be taken into account. This paper studies the new orthotropic plate by the experimental tests.
The design practice of structural engineering is currently undergoing a considerable amount of fundamental change. For example, in recent years, limit state design has been introduced in Europe for the design of steel structures, and load and resistance factor design has become mandatory in the United States. However, other more dramatic changes in the practice of structural steel design attributable to a shift in the design philosophy as evidenced by the introduction of numerous new codes and standards that now require design for stability and ductility response. This paper discusses the yield mechanism forms of different solutions of the connections of trapezoidal stiffeners and cross beams for orthotropic steel plates.
In traditional orthotropic plates the trapezoidal longitudinal stiffener is welded to the transverse girder web and to the bottom flange of the main girder. In a recently developed orthotropic plate the stiffeners and the transverse girder web are not connected. This approach provides for a significant reduction in the amount of flame cutting and welding, but more importantly there is no longer a need to assess the fatigue condition of the weld between the stiffener and the web. On the other hand, the potential for local buckling of the free edge of the web near the trapezoidal stiffener must be considered.
In this overview of loaded stiffened plates various types, loadings, and stiffener shapes are investigated. Mikami and API methods are used for the optimum design and comparison of the two methods. Both methods consider the effect of initial imperfection and residual welding stresses, but their empirical formulae are different. The elastic secondary deflection due to compression and lateral pressure is calculated using the Paik's solution of the differential equation for orthotropic plates, and the self-weight is also taken into account. The unknowns are the thickness of the base plate as well as the dimensions and number of stiffeners. The cost function to be minimized includes two kinds of material and three kinds of welding costs.
Authors:Mohamed Tahiri, Abdellatif Khamlichi and Mohammed Bezzazi
] M. D. Martínez-Rodrigo and P. Museros , “ Optimal design of passive viscous dampers for controlling the resonant response of orthotropicplates under high-speed moving loads ,” J. Sound Vib. , vol. 330 , pp. 1328 – 1351 , 2011 . 10.1016/j