• 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.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.135-140
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• 2001

A post-tensioned reinforced concrete slab bridge is analyzed by specially orthotropic laminate theory. Symmetrically reinforced slab with tension and compression steel is considered for convenience of analysis. Each longitudinal and transverse steel layer is regarded as a lamina, and material constants of each lamina is calculated by the use of the rule of mixture. This bridge is under uniformly distributed vertical loads, and axial loads and end moments due to post-tensioning. In this paper, finite difference method is used for numerical analysis of this bridge. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used for design of new bridges, and maintenance and repair of old bridges.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.141-146
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• 2001

A post-tensioned steel plate girder bridge with cross-beams is analyzed by specially orthotropic laminate theory. The cross-sections of both girders and cross-beams are WF types. The result is compared with that of the beam theory. This bridge with simple support is under uniformly distributed vertical load, and axial loads and moment due to post-tension. In this paper, finite difference method for numerical analysis of simple supported bridge is developed. Relatively exact solution is obtained even with small number of meshes. Theory and analysis method of specially orthotropic laminate plates used in this paper can be used in design of new bridges, and maintenance and repair of old bridges.

• 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.7 no.1
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• pp.53-67
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• 1999

The natural frequencies and modes of free vibration of specially orthotropic elliptic and circular plates are analysed using the Rayleigh-Ritz method. The assumed functions used are two-dimensional boundary characteristic orthogonal polynomials which are generated using the Gram-Schmidt orthogonalization procedure. The first five natural frequencies are reported here for various values of aspect ratio of the ellipse. Results are given for various boundary conditions at the edges i.e., the boundary may be any of clamped, simply-supported or fret. Numerical results are presented here for several orthotropic material properties. For rectilinear orthotropic circular plates, a few results are available in the existing literature, which are compared with the present results and are found to be in good agreement.

• 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.

• 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 Korean Society of Steel Construction
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• v.14 no.1
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• pp.23-29
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• 2002

Many of the bridge systems, including the girders and cross-beams, and concrete decks behave as the special orthotropic plates. Such systems with boundary conditions other than Navier or Levy solution types, or with irregular cross sections, analytical solution is very difficult to obtain. Numerical method for eigenvalue problems are also very much involved in seeking such a solution. A method of calculating the natural frequency corresponding to the first mode of vibration of beam and tower structures with irregular cross-sections was developed and reported by Kim in 1974. Recently, this method was extended to two dimensional problems including composite laminates, and has been applied to composite plates with shear deformation effects. In this paper, application of this method to the specially orthotropic laminated plates with various boundary condition is accomplished and the result of analysis is presented.

• Journal of Korean Society of Steel Construction
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• v.16 no.3 s.70
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• pp.333-344
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• 2004

In civil engineering applications, the establishment of standards and procedures for analysis, design, fabrication, construction, and quality control are essential in facilitating the economic and efficient use of composite materials. Many bridge systems, including girders. cross beams, and concrete decks, function as specially orthotropic plates. in general, the analytical solution for such complex systems is very difficult to achieve. Thus, the finite difference method is used for the analysis of the problem. The rate of tensile strength reduction due to increased size is considered. Strength reduction is necessary to ensure the safe design of building structures. This paper suggests the use of a strength-failure analysis procedure using the reduced tensile strength. A numerical study is conducted for different cases. The Tasi-Wu failure criterion for stress space is also used.

• Composites Research
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• v.23 no.1
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• pp.23-30
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• 2010

Most of the bridge systems, including the girders, cross-beams, and concrete decks behave as specially orthotropic plates. In general, the analytical solution for such complex system is very difficult to obtain. In this paper presented, a design method of slab bridge of simple supported made by composite materials. For the design of bridge made by the composite materials, cross-section was used the form-core shape because of this shape is economical and profitable, and for output of the stress value used finite difference method. In this paper, the rate of tensile strength reduction due to increased size was considered. Strength-failure analysis procedure, using the reduced tensile strength, was presented. And also numerical study was made for these cases.