• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.293-300
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• 2013

In this study we proposed a simplified finite element model of anchor bolt system inserted through concrete structures considering clamping forces. The three different finite element types using LS-DYNA are applied for numerical efficiency of the anchor bolt modeling. Combined beam and solid elements are used to reflect the tension state at internal part of anchor bolt due to torques. The clamping forces due to torques are considered by introducing a compression for a nut plane modeled by beam elements. The numerical examples show good agreement with different element types. Parametric studies are focused on the various effects of different element types on the induced axial and shear forces of anchor bolts considering clamping forces.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.716-721
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• 2004

Several Solid Freeform Fabrication Systems(SFFS) are commercialized in a few companies for rapid prototyping. However, they have many technical problems including the limitation of applicable materials. A new method of speedy prototyping is required for the recent manufacturing environments of multi-item and small quantity production. The objectives of this paper include the development of a novel method of SFFS, the ${CAFL}^{VM}$(Computer Aided Fabrication of Lamination for Various Material), and the manufacture of the various material samples for the certification of the proposed system and the creation of new application areas. For these objectives, the technologies for a highly accurate robot path control, the optimization of support structure, CAD modeling, adaptive slicing was implemented. In this paper, we design an algorithm that the cutting path of a laser beam which is controlled with constant speed. The laser beam is tangentially controlled in order to solve the inaccuracy of a 3D model surface. The designed algorithm for constant-speed path control and tangent-cutting control is implemented and experimented in the ${CAFL}^{VM}$ system.

• Smart Structures and Systems
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• v.7 no.5
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• pp.417-432
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• 2011

The present paper is devoted to vibration canceling and shape control of piezoelastic slender beams. Taking into account the presence of electric networks, an extended electromechanically coupled Bernoulli-Euler beam theory for passive piezoelectric composite structures is shortly introduced in the first part of our contribution. The second part of the paper deals with the concept of passive shape control of beams using shaped piezoelectric layers and tuned inductive networks. It is shown that an impedance matching and a shaping condition must be fulfilled in order to perfectly cancel vibrations due to an arbitrary harmonic load for a specific frequency. As a main result of the present paper, the correctness of the theory of passive shape control is demonstrated for a harmonically excited piezoelelastic cantilever by a finite element calculation based on one-dimensional Bernoulli-Euler beam elements, as well as by the commercial finite element code of ANSYS using three-dimensional solid elements. Finally, an outlook for the practical importance of the passive shape control concept is given: It is shown that harmonic vibrations of a beam with properly shaped layers according to the presented passive shape control theory, which are attached to an resistor-inductive circuit (RL-circuit), can be significantly reduced over a large frequency range compared to a beam with uniformly distributed piezoelectric layers.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.523-532
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• 2006

It is thought that the suggestion of efficient and rational design guideline based on the behavior evaluation of bridge structure system the included cross beam is necessary for the construction efficiency of two-I girder steel bridges. Therefore, in this study, the effects of influence parameters are investigated by the behavior analyses of the bridges, in which the influence parameters are location, spacing and rigidity of the cross beam. For this study, the existed two-I girder steel bridges firstly were selected with the model of case study and the FE analyses for some case models were performed to estimate the action of the cross beam in the bridge. From the analyses, it was estimated that if it consider local stress and load distribution of a floor system, shell and solid elements are compatible to modeling of the cross beams. Also, the efficient design guideline for the cross beam of two-I girder steel bridge was suggested from parameter studies used location, spacing and rigidity of the cross beam.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.376-386
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• 2020

The aim of this study was to develop a new efficient strategy that uses the Vector form Intrinsic Finite-element (VFIFE) method to conduct the static and dynamic analyses of marine pipes. Nonlinear problems, such as large displacement, small strain, and contact and collision, can be analyzed using a unified calculation process in the VFIFE method according to the fundamental theories of point value description, path element, and reverse motion. This method enables analysis without the need to integrate the stiffness matrix of the structure, because only motion equations of particles established according to Newton's second law are required. These characteristics of the VFIFE facilitate the modeling and computation efficiencies in analyzing the nonlinear dynamic problem of flexible pipe with large deflections. In this study, a three-dimensional (3-D) dynamical model based on 3-D beam element was established according to the VFIFE method. The deep-sea flexible pipe was described by a set of spatial mass particles linked by 3-D beam element. The motion and configuration of the pipe are determined by these spatial particles. Based on this model, a simulation procedure to predict the 3-D dynamical behavior of flexible pipe was developed and verified. It was found that the spatial configuration and static internal force of the mining pipe can be obtained by calculating the stationary state of pipe motion. Using this simulation procedure, an analysis was conducted on the static and dynamic behaviors of the flexible mining pipe based on a 1000-m sea trial system. The results of the analysis proved that the VFIFE method can be efficiently applied to the static and dynamic analyses of marine pipes.

• Steel and Composite Structures
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• v.20 no.1
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• pp.167-184
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• 2016

This paper presents the details of Finite Element (FE) analysis carried out to determine the limiting deformation capacity and failure mode of Laced Steel-Concrete Composite (LSCC) beam, which was proposed and experimentally studied by the authors earlier (Anandavalli et al. 2012). The present study attains significance due to the fact that LSCC beam is found to possess very high deformation capacity at which range, the conventional laboratory experiments are not capable to perform. FE model combining solid, shell and link elements is adopted for modeling the beam geometry and compatible nonlinear material models are employed in the analysis. Besides these, an interface model is also included to appropriately account for the interaction between concrete and steel elements. As the study aims to quantify the limiting deformation capacity and failure mode of the beam, a suitable damage model is made use of in the analysis. The FE model and results of nonlinear static analysis are validated by comparing with the load-deformation response available from experiment. After validation, the analysis is continued to establish the limiting deformation capacity of the beam, which is assumed to synchronise with tensile strain in bottom cover plate reaching the corresponding ultimate value. The results so found indicate about $20^{\circ}$ support rotation for LSCC beam with $45^{\circ}$ lacing. Results of parametric study indicate that the limiting capacity of the LSCC beam is more influenced by the lacing angle and thickness of the cover plate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.667-676
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• 2002

Many studies on the finite element modeling for bolted joints have proceeded, but the structures with bolted joints are complicated in shape and it is difficult to find out the characteristics according to joint condition. Usually, experimental methods have been used for bolted joint analysis. A reliable and practical finite element modeling technique for structure with bolted joints is very important for engineers in industry. In this study, three kinds of model are presented; a detailed model, a practical model and a simple model. The detailed model is modeled by using 3-D solid element and gap element, and the practical model is modeled by using shell element (a portion of bolt head) and beam element (a portion of bolt body), the simple model is modeled by simplifying practical model without using gap elements. Among these models, the simple model has the least degree of freedom and show the effect of memory reduction of 59%, when compared with the detailed model.

• Structural Engineering and Mechanics
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• v.12 no.2
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• pp.201-214
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• 2001

Four finite element (FE) models are examined to find the one that best estimates moment-rotation characteristics of top- and seat-angle with double web-angle connections. To efficiently simulate the real behavior of connections, finite element analyses are performed with following considerations: 1) all components of connection (beam, column, angles and bolts) are discretized by eight-node solid elements; 2) shapes of bolt shank, head, and nut are precisely taken into account in modeling; and 3) contact surface algorithm is applied as boundary condition. To improve accuracy in predicting moment-rotation behavior of a connection, bolt pretension is introduced before the corresponding connection moment being surcharged. The experimental results are used to investigate the applicability of FE method and to check the performance of three-parameter power model by making comparison among their moment-rotation behaviors and by assessment of deformation and stress distribution patterns at the final stage of loading. This research exposes two important features: (1) the FE method has tremendous potential for connection modeling for both monotonic and cyclic loading; and (2) the power model is able to predict moment-rotation characteristics of semi-rigid connections with acceptable accuracy.

• Land and Housing Review
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• v.4 no.3
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• pp.271-277
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• 2013

The BNWF (Beam on Nonlinear Winkler Foundation) model is one of the simplest idealizations for a pile embedded in soil as it ignores the continuity of the soil. This method is difficult to model the behavior of pile group foundation subjected to lateral loading. The limitation can be overcome with the utilization of the finite element method (FEM) or finite different method (FDM) to represent a pile element embedded in a soil medium. Both the ground and piles are modeled with soild elements. The solid elements, which do not have rotational degree of freedom, is not appropriate for modeling piles. It can be overcome by substantially increasing the number of elements, which can be prohibitive for 3D modeling. This paper used the beam element and rigid link incorporated in the OpenSees to model the pile. The accuracy of the model is validated through comparison with lateral load test and BNWF analysis. It is shown that the method can capture the measured behavior accurately. It is therefore recommended to be used in group pile analyses.

• Steel and Composite Structures
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• v.24 no.5
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• pp.549-559
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• 2017

As few multi-tower single-box multi-cell cable-stayed bridges with corrugated steel webs have been built, analysis is mostly achieved by combining single-girder model, beam grillage model and solid model in support of the design. However, such analysis methods usually suffer from major limitations in terms of the engineering applications: single-girder model fails to account for spatial effect such as shear lag effect of the box girder and the relevant effective girder width and eccentric load coefficient; owing to the approximation in the principle equivalence, the plane grillage model cannot accurately capture shear stress distribution and local stress state in both top and bottom flange of composite box girder; and solid model is difficult to be practically combined with the overall calculation. The usual effective width method fails to provide a uniform and accurate "effective length" (and the codes fail to provide a unified design approach at those circumstance) considering different shear lag effects resulting from dead load, prestress and cable tension in the construction. Therefore, a novel spatial grid model has been developed to account for shear lag effect. The theoretical principle of the proposed spatial grid model has been elaborated along with the relevant illustrations of modeling parameters of composite box girder with corrugated steel webs. Then typical transverse and longitudinal shear lag coefficient distribution pattern at the side-span and mid-span key cross sections have been analyzed and summarized to provide reference for similar bridges. The effectiveness and accuracy of spatial grid analysis methods has been finally validated through a practical cable-stayed bridge.