• Land and Housing Review
• /
• 제5권2호
• /
• pp.91-97
• /
• 2014

An experimental program was initiated to investigate the structural capacity of PC (Precast Concrete) beam-column joints used for the underground parking structure. Static testing of 4 typical PC beam-column joints specimens was conducted. Specimens were designed to span a range of parameters typically encountered for such members, based on findings from the survey of existing PC joint details used in the construction fields in Korea. The specimens were four by their joint types and testing parameters. The specific structural behavior germane to each specimen, and general observations on overall member behavior as a function of the considered parameters, are reported. From the results of tests on four PC joints specimens, the beam-column joints of PC structure used for the underground parking building was found to have similar structural capacities when comparing to the cast-in-place concrete system.

• Computational Structural Engineering
• /
• 제10권2호
• /
• pp.233-242
• /
• 1997

The main purpose of this paper is to investigate the dynamic optimal design of continuous beams. The computer-aided optimization technique is used to obtain the near-optimal parameters of continuous beam. The computer program is developed to obtain the natural frequency parameters and the forced vibration responses to a transit point load for the continuous beam with variable support spacing, mass and stiffness. The model test data is in good agreement with the computer calculation, which serves to validate the mathematical analysis. The optimization function to describe the design efficiency is defined as a linear combination of four dimensionless span characteristics; the maximum dynamic stress; the stress difference between span segments; the rms deflection under the transit point load; and the total span mass. Studies of three span beams show that the beam with near-optimal parameters can improve design efficiency when compared to a uniform beam with even spacing of the same total span length.

• Journal of the Korean Recycled Construction Resources Institute
• /
• 제11권4호
• /
• pp.467-475
• /
• 2023

To ensure the safety of the pipeline against large deformation of the pipeline during lowering construction, the analysis for pipeline becomes emphasized. The FE analysis has a lower efficiency at calculating time, while it could be obtained high accuracy. In this paper, a reasonable analytical model for analysis of pipeline is proposed during lowering-in. This analytical model is partitioned considering the geometrical characteristics and modeled as two parameters Beam On Elastic Foundation and Euler-Bernoulli beam considering the boundary condition. This takes into account the pipeline-soil interaction and the axial forces acting on the pipeline. Previous model can only be applied to standardized conditions, whereas the proposed model defined as Segmented Pipeline Model can be considered for the majority of construction conditions occurred during lowering-in. In addition, minimized assumptions and segmented elements lead to improve the convenience and applicability of modeling. Nevertheless, the model shows accurate results compared to the FE model. Accordingly, it is expected that it will be used efficiently for configuration management as well as safety assessment of pipeline during lowering-in.

• Structural Engineering and Mechanics
• /
• 제52권2호
• /
• pp.323-349
• /
• 2014

In this paper, linear buckling analysis of a curved sandwich beam with a flexible core is investigated. Derivation of equations for face sheets is accomplished via the classical theory of curved beam, whereas for the flexible core, the elasticity equations in polar coordinates are implemented. Employing the von-Karman type geometrical non-linearity in strain-displacement relations, nonlinear governing equations are resulted. Linear pre-buckling analysis is performed neglecting the rotation effects in pre-buckling state. Stability equations are concluded based on the adjacent equilibrium criterion. Considering the movable simply supported type of boundary conditions, suitable trigonometric solutions are adopted which satisfy the assumed edge conditions. The critical uniform load of the beam is obtained as a closed-form expression. Numerical results cover the effects of various parameters on the critical buckling load of the curved beam. It is shown that, face thickness, core thickness, core module, fiber angle of faces, stacking sequence of faces and openin angle of the beam all affect greatly on the buckling pressure of the beam and its buckled shape.

• Structural Engineering and Mechanics
• /
• 제48권4호
• /
• pp.519-545
• /
• 2013

An outline of the Timoshenko beam theory is presented. Two differential equations of motion in terms of deflection and rotation are comprised into single equation with deflection and analytical solutions of natural vibrations for different boundary conditions are given. Double frequency phenomenon for simply supported beam is investigated. The Timoshenko beam theory is modified by decomposition of total deflection into pure bending deflection and shear deflection, and total rotation into bending rotation and axial shear angle. The governing equations are condensed into two independent equations of motion, one for flexural and another for axial shear vibrations. Flexural vibrations of a simply supported, clamped and free beam are analysed by both theories and the same natural frequencies are obtained. That fact is proved in an analytical way. Axial shear vibrations are analogous to stretching vibrations on an axial elastic support, resulting in an additional response spectrum, as a novelty. Relationship between parameters in beam response functions of all type of vibrations is analysed.

• Structural Engineering and Mechanics
• /
• 제49권5호
• /
• pp.537-554
• /
• 2014

In this paper, free vibration of a sandwich curved beam with a functionally graded (FG) core was investigated. Closed-form formulations of two-dimensional (2D) refined higher order beam theory (RHOBT) without neglecting the amount of z/R was derived and used. The present RHOBT analysis incorporated a trapezoidal shape factor that arose due to the fact that stresses through the beam thickness were integrated over a curved surface. The solutions presented herein were compared with the available numerical and analytical solutions in the related literature and excellent agreement was obtained. Effects of some dimensionless parameters on the structural response were investigated to show their effects on fundamental natural frequency of the curved beam. In all the cases, variations of the material constant number were calculated and presented. Effect of changing ratio of core to beam thickness on the fundamental natural frequency depended on the amount of the material constant number.

• Steel and Composite Structures
• /
• 제21권5호
• /
• pp.999-1016
• /
• 2016

This study presents free vibration of beam made of porous material. The mechanical properties of the beam is variable in the thickness direction and the beam is investigated in three situations: poro/nonlinear nonsymmetric distribution, poro/nonlinear symmetric distribution, and poro/monotonous distribution. First, the governing equations of porous beam are derived using principle of virtual work based on Euler-Bernoulli theory. Then, the effect of pores compressibility on natural frequencies of the beam is studied by considering clamped-clamped, clamped-free and hinged-hinged boundary conditions. Moreover, the results are compared with homogeneous beam with the same boundary conditions. Finally, the effects of poroelastic parameters such as pores compressibility, coefficients of porosity and mass on natural frequencies has been considered separately and simultaneously.

• Journal of Institute of Convergence Technology
• /
• 제5권2호
• /
• pp.21-25
• /
• 2015

This paper proposes a fabrication process of deposited layer with micro patterns that uses a combination of a pulsed laser beam machining and an electrodeposition. This process consists of the electrodeposition and the laser beam machining. The deposited layer on metal can be selectively eliminated by laser ablation. As a result, the deposited layer with micro patterns can be fabricated without a mask. The characteristics of the deposited layer on stainless steel were investigated according to the average power and marking speed in the pulsed laser beam machining. The optimal laser beam conditions for precise micro patterning of the deposited layer were determined. Finally, the deposited copper layer with micro text was successfully fabricated by the pulsed laser beam machining.

• Steel and Composite Structures
• /
• 제15권2호
• /
• pp.175-202
• /
• 2013

The super convergent laminated composite beam element is newly derived for the lateral stability analysis. For this, a theoretical model of the laminated composite beams is developed based on the first-order shear deformation beam theory. The present laminated beam takes into account the transverse shear and the restrained warping induced shear deformation. The second-order coupling torque resulting from the geometric nonlinearity is rigorously derived. From the principle of minimum total potential energy, the stability equations and force-displacement relationships are derived and the explicit expressions for the displacement parameters are presented by applying the power series expansions of displacement components to simultaneous ordinary differential equations. Finally, the member stiffness matrix is determined using the force-displacement relationships. In order to show accuracy and superiority of the beam element developed by this study, the critical lateral buckling moments for bisymmetric and monosymmetric I-beams are presented and compared with other results available in the literature, the isoparametric beam elements, and shell elements from ABAQUS.

• Structural Engineering and Mechanics
• /
• 제27권5호
• /
• pp.555-574
• /
• 2007

Static response of an elastic beam on a two-parameter tensionless foundation is investigated by assuming that the beam is symmetrically subjected to a uniformly distributed load and concentrated edge loads. Governing equations of the problem are obtained and solved by pointing out that a concentrated edge foundation reaction in addition to a continuous foundation reaction along the beam axis in the case of complete contact and a discontinuity in the foundation reactions in the case of partial contact come into being as a direct result of the two-parameter foundation model. The numerical solution of the complete contact problem is straightforward. However, it is shown that the problem displays a highly non-linear character when the beam lifts off from the foundation. Numerical treatment of the governing equations is accomplished by adopting an iterative process to establish the contact length. Results are presented in figures to demonstrate the linear and non-linear behavior of the beam-foundation system for various values of the parameters of the problem comparatively.