• Computers and Concrete
• /
• v.29 no.2
• /
• pp.117-126
• /
• 2022

The vibrational characteristic of three-layered cylindrical shell (CS) submerged in fluid with the ring support has been studied. The inner and outer layer is supposed to construct by isotropic layer. The composition of central layer is of functionally graded material type. Acoustic Wave condition has been utilized to present the impact of fluid. The central layer of cylindrical shell (CS) varies by volume fraction law that has been expressed in terms of polynomial. The main shell frequency equation has been obtained by theory of Love's shell and Rayleigh-Ritz technique. The oscillation of natural frequency has been examined under a variety of end conditions. The dependence of axial model has been executed with the help of characteristic beam function. The natural frequencies (NFs) of functionally graded material (FGM) shell have been observed of cylindrical shell along the shell axial direction. Different physical parameters has been used to examine the vibration characteristics due to the effect of volume fraction law. MATLAB software has been used to get result.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.19 no.3
• /
• pp.103-108
• /
• 2015

This work introduces a modal testing and analysis results of the mock-up for a layered stone pagoda. The pagoda has been horizontally excited by an impact hammer. As to the measured acceleration time responses, the first five lower mode shapes and natural frequency are extracted by the TDD technique. It is observed that the time delay of a shear wave occurs through friction surfaces. Such phenomena cannot be described by using the traditional analytical models such as a continuum cantilever beam model or a discrete shear building model. However, the time delay typically affects only the phases of the pagoda system. The frequencies of the pagoda system are not affected by such time delay. It is found in the first time that the layered stone pagoda system has a set of closely placed modes in near of natural frequency. It is believed that such modes are due to the friction characteristics in friction surfaces. Based on the stick-slip friction model, it seems that the one of the closely placed mode can be a self-excited one.

• Structural Engineering and Mechanics
• /
• v.4 no.3
• /
• pp.243-255
• /
• 1996

This paper presents a model of a layered, delaminated composite beam. The beam is modelled by beam finite elements, and the delamination is modelled by additional boundary conditions. In the present study, the laminated beam contains only one delaminated region through the thickness direction which extends to the full width of the beam. It is also assumed that the delamination is open. The influence of the delamination length and position upon changes in the bending natural frequencies of the composite laminated cantilever beam is investigated.

• Structural Engineering and Mechanics
• /
• v.43 no.1
• /
• pp.15-30
• /
• 2012

A damped Timoshenko beam element is introduced for the DOF-efficient forced vibration analysis of beam-like structures coated with viscoelastic damping layers. The rotary inertia as well as the shear deformation is considered, and the damping effect of viscoelastic layers is modeled as an imaginary loss factor in the complex shear modulus. A complex composite cross-section of structures is replaced with a homogeneous one by means of the transformed section approach in order to construct an equivalent single-layer finite element model capable of employing the standard $C^{0}$-continuity basis functions. The numerical reliability and the DOF-efficiency are explored through the comparative numerical experiments.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.10a
• /
• pp.190-197
• /
• 2000

A moment-curvature relationship to simulate the behavior of reinforced concrete beam under cyclic loading is introduced. Unlike previous moment-curvature models and the layered section approach, the proposed model takes into consideration the bond-slip effect by using monotonic moment-curvature relationship constructed on the basis of the bond-slip relation and corresponding equilibrium equation at each nodal point. In addition, the use of curved unloading and reloading branches inferred from the stress-strain relation of steel gives more exact numerical result. The advantages of the proposed model, comparing to layered section approach, may be on the reduction in calculation time and memory space in case of its application to large structures. The modification of the moment-curvature relation to reflect the fixed-end rotation and pinching effect is also introduced. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

• Journal of the Korean Society of Industry Convergence
• /
• v.11 no.1
• /
• pp.35-40
• /
• 2008

Various characters of the concrete are greatly improved as the effect of the steel fiber. As the improvement effect of the steel fiber, the increment in flexural strength, shear strength, toughness, and impact strength are remarkable, and tenacious concrete is obtained. This paper presents model which can predict mechanical behavior of the structure according to aspect ratio and volume fraction of steel fiber. Experiments on compressive strength, elastic modulus and tensile strength were performed with self-made cylindrical specimens of variable aspect ratios. This paper presents an analytical study on the behavior of a beam specimen with steel fiber reinforced concrete(SFRC). The effect of the SFRC on the crack pattern, failure mode and the flexural behavior of the structure were investigated. The analysis model based on the nonlinear layered finite element method was successfully able to find the necessary amount of steel fibers, tensile steels and beam section which can best approximate flexural strength and ductility of a given conventionally reinforced concrete beam.

• KCI Concrete Journal
• /
• v.12 no.2
• /
• pp.11-21
• /
• 2000

It is not easy to correctly predict deflections of reinforced concrete beams and one-way slabs due to the variability of parameters involved in the calculation of deflections. Monte Carlo simulation is used to assess the variability of deflections with known statistical data and probability distributions of variables. A deterministic deflection value is obtained using the layered beam model based on the finite element approach in which a finite element is divided into a number of layers over the depth. The model takes into account nonlinear effects such as cracking, creep and shrinkage. Statistical parameters were obtained from the literature. For the assessment of variability of deflections, 12 cases of one-way slabs and T-beams are designed on the basis of ultimate moment capacity. Several results of a probabilistic study are presented to indicate general trends indicated by results and demonstrate the effect of certain design parameters on the variability of deflections. From simulation results, the variability of deflections relies primarily on the ratio of applied moment to cracking moment and the corre-sponding reinforcement ratio.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1998.04b
• /
• pp.541-546
• /
• 1998

The use of steel fibers in conventional reinforced concrete increases the strength and ductility under various loading conditions. In order to examine the possibility of the use of these combinations achieving required strength and ductility of a reinforced concrete beam, a refined optimization procedure based on nonlinear layered finite element method and nonlinear programming technique is developed in this study. Six design variables-beam width and depth, fiber volume fraction, amounts of tensile and compressive rebars, and stirrup, and stirrup spacing-are considered. The developed model can be used as a tool in determining the economical use of steel fibers in designing the reinforced steel fibrous concrete beam.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1996.10a
• /
• pp.221-229
• /
• 1996

An analytical method based on the nonlinear layered finite element method is used to simulate the load-deflection behavior of strengthened beam. Beams considered in this study are the ones strengthened either with external steel plate or Carbon Fiber Reinforced Plastic (CFRP) sheets bonded to the overlay soffit or with reinforcing rebars in the overlay. The theoretically obtained load-deflections and strains of the strengthened beam are compared to the corresponding experimental values. Comparing the approximate measures on the cumulative slips, efficiencies of the repairing techniques are evaluated. Parametric studies are, then, peformed using the developed model to investigate the effects of design variables on the overal flexural behavior of the strengthened beam. Simply supported beams under monotonically increasing symmetrical loads are considered exclusively.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.467-470
• /
• 1999

An analytical method based on the nonlinear layered finite element method is developed to simulate overall load-deflection behavior of bonded and unbonded prestressed concrete beams. The model which uses rather advanced numerical technique for iterative convergence to equilibrium can be regarded as superior one compared to the models mainly based on either load control or displacement control methods. Model predictions were compared with preceding experimental results and it was observed that there were good agreements between them.