• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.115-124
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• 2003

A prestressed concrete slab bridge is analyzed by the specially orthotropic laminates theory. Both the geometry and the material of the cross section of the slab are considered symmetrical with respect to the mid-surface so that the bending extension coupling stiffness, $B_{ij}=0$, and $D_{16}=D_{26}=0$. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of rule of mixture. This bridge with simple support is under uniformly distributed vertical and axial loads. In this paper, the finite difference method and the beam theory are used for analysis. The result of beam analysis is modified to obtain the solution of the plate analysis.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.105-111
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• 2002

A post-tensioned slab bridge is analyzed by the specially orthotropic laminates theory. Both the geometry and the material of the cross section of the slab are considered symmetrical with respect to the mid-surface so that the bending extension coupling stiffness, $B_{ij}=0$, and $D_{16}=D_{26}=0$. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of rule of mixture. This bridge with simple support is under uniformly distributed vertical and axial loads. In this paper, the finite difference method and the beam theory are used for analysis. The result of beam analysis is modified to obtain the solution of the plate analysis. The result of this paper can be used for post-tensioned slab bridge analysis by the engineers with undergraduate study in near future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.219-225
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• 2011

Advanced composite structures are too difficult for such design engineers for construction and some simple but accurate enough methods are necessary. The simply supported laminated plates are analyzed by the specially orthotropic laminates theory. This method, however, may be too difficult for some practising engineers. In this paper, the result of analysis for such plate by means of the beam theory with unit width is reported. The plate aspect ratio considered is from 1 : 1 to 1 : 5. Most of the bridge and building slabs on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms($M_x$) on the relevant partial differential equations of equilibrium. In this paper. the influence of the aspect ratio on the natural frequency of the specially orthotropic laminated plates is studied and it is concluded that the method used is sufficiently accurate for engineering purposes. The result of this paper can be used for simply supported laminated plates analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.789-799
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• 1987

The stress state and displacement for the orthotropic cylindrical shell subjected to line load along a generator is presented. It is assumed that the behavior of the material is specially-orthotropic. The governing equation for orthotropic cylindrical shell is derived on the basis of Novozhilov's shell theory. General solution is obtained by extending the Naghdi's method for the isotropic cylindrical shell under the line load. Numerical examples are presented for circular cylindrical shells having various othotropic material properties and geometries.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.81-89
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• 2003

The simple supported reinforced concrete slab bridges are analyzed by the specially orthotropic laminates theory. This method, however, may be too difficult for some practising engineers. In this paper, the result of analysis for such plate by means of the beam theory with unit width is reported. By using the "correction factor", the accurate solution for the plate can be obtained by the beam theory. The result of this paper can be used for reinforced concrete slab bridges analysis by the engineers with undergraduate study in near future.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.3
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• pp.42-47
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• 2011

A method of calculating natural frequencies corresponding to the modes of vibration of beams and tower structures with irregular cross sections and arbitrary boundary conditions was developed. The result is compared with that of the beam theory. Finite difference method is used for this purpose. The influence of the $D_{22}$ stiffness on the natural frequency is rigorously investigated. In this paper, the relation between the applied loading sizes and the natural frequency of vibration of some structural elements is presented. The results of application of this method to steel bridge and reinforced concrete slab bridge by using specially orthotropic plate theory is presented.

• Composites Research
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• v.27 no.1
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• pp.1-6
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• 2014

Theories for composite material structures are too difficult for such design engineers for construction and some simple but accurate enough methods are necessary. The author has reported that some laminate orientations have decreasing values of $D_{16}$, $B_{16}$, $D_{26}$ and $B_{26}$ stiffnesses as the ply number increases. For such plates, the fiber orientations given above behave as specially orthotropic plates and simple formulas developed by the author. Most of the bridge deck structures on girders have large aspect ratios. For such cases further simplification is possible by neglecting the effect of the longitudinal moment terms $M_x$ on the relevant partial differential equations of equilibrium. In this paper, the result of the study on the subject problem is presented.

• Journal of Ship and Ocean Technology
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• v.4 no.2
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• pp.38-57
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• 2000

This paper deals with reliability analysis of specially orthotropic plates subjected to transverse lateral pressure loads by using Monte Carlo simulation method. The plates are simply supported around their all edges and have a low short span to plate depth ratio with rectangular plate shapes. Various levels of reliability analyses of the plates are performed within the context of First-Ply-Failure(FPF) analysis such as ply-/laminate-level reliability analyse, failure tree analysis and sensitivity analysis of basic design variables to estimated plate reliabilities. In performing all these levels of reliability analyses, the followings are considered within the Monte Carlo simulation method: (1) input parameters to the strengths of the plates such as applied transverse lateral pressure loads, elastic moduli, geometric including plate thickness and ultimate strength values of the plates are treated as basic design variables following a normal probability distribution; (2) the mechanical responses of the plates are calculated by using simplified higher-order shear deformation theory which can predict the mechanical responses of thick laminated plates accurately; and (3) the limit state equations are derived from polynomial failure criteria for composite materials such as maximum stress, maximum strain, Tsai-Hill, Tsai-Wu and Hoffman.

• Structural Engineering and Mechanics
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• v.65 no.4
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• pp.491-504
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• 2018

Because of sandwich structures with low weight and high stiffness have much usage in various industries such as civil and aerospace engineering, in this article, buckling and free vibration analyses of coupled micro composite sandwich plates are investigated based on sinusoidal shear deformation (SSDT) and most general strain gradient theories (MGSGT). It is assumed that the sandwich structure rested on an orthotropic elastic foundation and make of four composite face sheets with temperature-dependent material properties that they reinforced by carbon and boron nitride nanotubes and two flexible transversely orthotropic cores. Mathematical formulation is presented using Hamilton's principle and governing equations of motions are derived based on energy approach and applying variation method for simply supported edges under electro-magneto-thermo-mechanical, axial buckling and pre-stresses loadings. In order to predict the effects of various parameters such as material length scale parameter, length to width ratio, length to thickness ratio, thickness of face sheets to core thickness ratio, nanotubes volume fraction, pre-stress load and orthotropic elastic medium on the natural frequencies and critical buckling load of double-bonded micro composite sandwich plates. It is found that orthotropic elastic medium has a special role on the system stability and increasing Winkler and Pasternak constants lead to enhance the natural frequency and critical buckling load of micro plates, while decrease natural frequency and critical buckling load with increasing temperature changes. Also, it is showed that pre-stresses due to help the axial buckling load causes that delay the buckling phenomenon. Moreover, it is concluded that the sandwich structures with orthotropic cores have high stiffness, but because they are not economical, thus it is necessary the sandwich plates reinforce by carbon or boron nitride nanotubes specially, because these nanotubes have important thermal and mechanical properties in comparison of the other reinforcement.

• International Journal of Highway Engineering
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• v.16 no.3
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• pp.1-8
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• 2014

PURPOSES : The purpose of this paper is to demonstrate to the practicing engineers, how to apply the advanced composite materials theory to the road structures. For general construction material used, there is certain theoretical limit in sizes. For super road structure construction, the reduction in panel weight is the first step to take in order to break such size limits. METHODS : For a typical road structures panel, both concrete and advanced composite sandwich panels are considered. The concrete panel is treated as a special orthotropic plate. RESULTS : All types of advanced composite sandwich panels are considered as a self-weights less than one tenth of that of concrete panel. The concrete panel is treated as a special orthotropic plate to obtain more accurate result. CONCLUSIONS : Advanced composite sandwich panels are considered as a self-weights less than one tenth (10%) of that of concrete panel, with deflections less than that of the concrete panel. This conclusion gives good guide line for design of the light weight of road structures.