• Title/Summary/Keyword: spring joint connection

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Buckling Analysis for Single Layer Latticed Domes considering the Change of Joint Rigidity (접합부 강성변화를 고려한 단층 래티스 돔의 좌굴해석)

  • 이후진;권택진
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.10a
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    • pp.337-344
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    • 2001
  • This paper is concerned with the change of joint rigidity in estimating the degree of semi-rigidity of connections and the buckling load in a single layer latticed dome. The estimations are based on information about the ratio for the rotational stiffness of the connection to the flexural stiffness of the member and the minimum eigenvalue of a structure for pinned, semi-rigid and completely rigid cases, respectively. Connection characteristics are reflected in the ratio control of joint rigidity for the DOFs to be related using the spring element by FEM.

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Design and Analysis on The Connections of RC Precast Large Panel (철근콘크리트 프리캐스트 대형판 접합부의 설계 및 해석)

  • Park, Kang-Geun
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.2 s.20
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    • pp.85-92
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    • 2006
  • Precast large panel structures have various connection system such as the horizontal slab-to-wall connection, the vertical wall to wall connection, horizontal slab-to-slab connection, etc. Horizontal connection is connected by vertical tie bars, and vertical joint is connected loop bars and shear keys. The basic function is equalized deformations on later forces and the entire wall panel assembly acts as monolithic actions. Under lateral load some slip occurs in almost vertical connections. The shape and detail of precast connections are very important to the monolithic behavior of overall structures. The paper is a study on the design method and new elasto-plastic analysis of the connections by rigid-bodies spring model.

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Structural Joint Damage Assessment using Neural Networks (신경망을 이용한 구조물 접합부의 손상도 추정)

  • 방은영
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1998.04a
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    • pp.131-138
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    • 1998
  • Structural damage is used to be modeled through reductions in the stiffness of structural elements for the purpose of damage estimation of structural system. In this study, the concept of joint damage is employed for more realistic damage assessment of a steel structure. The joint damage is estimated damage based on the mode shape informations using neural networks. The beam-to-column connection in a steel frame structure is represented by a rotational spring at the fixed end of a beam element. The severity of joint damage is defined as the reduction ratio of the connection stiffness with respect to the value of the intact joint. The concept of the substructural identification is used for the localized damage assessment in a large structure. The feasibility of the proposed method is examined using an example with simulated data. It has been found that the joint damages can be reasonably estimated for the case with the measurements of the mode vectors subjected to noise.

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Exact External Torque Sensing System for Flexible-Joint Robot: Kalman Filter Estimation with Random-Walk Model (유연관절로봇을 위한 정확한 외부토크 측정시스템 개발: 랜덤워크모델을 이용한 칼만필터 기반 추정)

  • Park, Young-Jin;Chung, Wan-Kyun
    • The Journal of Korea Robotics Society
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    • v.9 no.1
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    • pp.11-19
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    • 2014
  • In this paper, an external torque estimation problem in one-degree-of-freedom (1-DOF) flexible-joint robot equipped with a joint-torque sensor is revisited. Since a sensor torque from the joint-torque sensor is distorted by two dynamics having a spring connection, i.e., motor dynamics and link dynamics of a flexible-joint robot, a model-based estimation, rather than a simple linear spring model, should be required to extract external torques accurately. In this paper, an external torque estimation algorithm for a 1-DOF flexible-joint robot is proposed. This algorithm estimates both an actuating motor torque from the motor dynamics and an external link torque from the link dynamics simultaneously by utilizing the flexible-joint robot model and the Kalman filter estimation based on random-walk model. The basic structure of the proposed algorithm is explained, and the performance is investigated through a custom-designed experimental testbed for a vertical situation under gravity.

Multi-component Topology Optimization Considering Joint Distance (조인트 최소거리를 고려한 다중구조물 위상최적설계 기법)

  • Jun Hwan, Kim;Gil Ho, Yoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.35 no.6
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    • pp.343-349
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    • 2022
  • This paper proposes a new topology optimization scheme to determine optimized joints for multi-component models. The joints are modeled as zero-length high-stiffness spring elements. The spring joints are considered as mesh-independent springs based on a joint-element interpolation scheme. This enables the changing of the location of the joints regardless of the connected nodes during optimization. Because the joints are movable, the locations of the optimized joints should be aggregated at several points. In this paper, the novel joint dispersal (JD) constraint to prevent joint clustering is proposed. With the joint dispersal constraint, it is possible to determine the optimized joint location as well as optimized topologies while maintaining the minimum distance between each joint. The mechanical compliance value is considered as the objective function. Several topology optimization examples are solved to demonstrate the effect of the joint dispersal constraint.

Fabrication and Experiment of Micromirror with Aluminum Pin-joint (알루미늄 핀-조인트를 사용한 마이크로 미러의 제작과 측정)

  • Ji, Chang-Hyeon;Kim, Yong-Gwon
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.8
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    • pp.487-494
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    • 2000
  • This paper describes the design, fabrication and experiments of surface-micromachined aluminum micromirror array with hidden pin-joints. Instead of the conventional elastic spring components as connection between mirror plate and supporting structure, we used pin-joint composed of pin and staples to support the mirror plate. The placement of pin-joint under the mirror plate makes large active surface area possible. These flexureless micromirrors are driven by electrostatic force. As the mirror plate has discrete deflection angles, the device can be ap;lied to adaptive optics and digitally-operating optical applications. Four-level metal structural layers and semi-cured photoresist sacrificial layers were used in the fabrication process and sacrificial layers were removed by oxygen plasma ashing. Static characteristics of fabricated samples were measured and compared with modeling results.

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Structural Joint Damage Assessment Using Neural Networks (신경망을 이용한 구조물 접합부의 손상도 추정)

  • 방은영;이진학;윤정방
    • Journal of the Earthquake Engineering Society of Korea
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    • v.2 no.1
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    • pp.35-46
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    • 1998
  • Structural damage is used to be modeled through reductions in the stiffness of structural elements for the purpose of damage estimation of structural system. In this study, the concept of joint damage is employed for more realistic damage assessment of a steel structure. The joint damage is estimated damage based on the mode shape informations using neural networks, The beam-to-column connection in a steel frame structure is represented by a rotational spring at the fixed end of a beam element. The severity of joint damage is defined as the reduction ratio of the connection stiffness with respect to the value of the intact joint. The concept of the substructural identification is used for the localized damage assessment in a large structure. The feasibility of the proposed method is examined using an example with simulated data. It has been found that the joint damages can be reasonably estimated for the case with the measurements of the mode vectors subjected to noise.

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A Study on Joint Damage Model and Neural Networks-Based Approach for Damage Assessment of Structure (구조물 손상평가를 위한 접합부 손상모델 및 신경망기법에 관한 연구)

  • 윤정방;이진학;방은영
    • Journal of the Earthquake Engineering Society of Korea
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    • v.3 no.3
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    • pp.9-20
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    • 1999
  • A method is proposed to estimate the joint damages of a steel structure from modal data using the neural networks technique. The beam-to-column connection in a steel frame structure is represented by a zero-length rotational spring of the end of the beam element, and the connection fixity factor is defined based on the rotational stiffness so that the factor may be in the range 0~1.0. Then, the severity of joint damage is defined as the reduction ratio of the connection fixity factor. Several advanced techniques are employed to develop the robust damage identification technique using neural networks. The concept of the substructural indentification is used for the localized damage assessment in the large structure. The noise-injection learning algorithm is used to reduce the effects of the noise in the modal data. The data perturbation scheme is also employed to assess the confidence in the estimated damages based on a few sets of actual measurement data. The feasibility of the proposed method is examined through a numerical simulation study on a 2-bay 10-story structure and an experimental study on a 2-story structure. It has been found that the joint damages can be reasonably estimated even for the case where the measured modal vectors are limited to a localized substructure and the data are severely corrupted with noise.

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A component method model for blind-bolts with headed anchors in tension

  • Pitrakkos, Theodoros;Tizani, Walid
    • Steel and Composite Structures
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    • v.18 no.5
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    • pp.1305-1330
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    • 2015
  • The successful application of the component-based approach - widely used to model structural joints - requires knowledge of the mechanical properties of the constitutive joint components, including an appropriate assembly procedure to derive the joint properties. This paper presents a component-method model for a structural joint component that is located in the tension zone of blind-bolted connections to concrete-filled tubular steel profiles. The model relates to the response of blind-bolts with headed anchors under monotonic loading, and the blind-bolt is termed the "Extended Hollo-bolt". Experimental data is used to develop the model, with the data being collected in a manner such that constitutive models were characterised for the principal elements which contribute to the global deformability of the connector. The model, based on a system of spring elements, incorporates pre-load and deformation from various parts of the blind-bolt: (i) the internal bolt elongation; (ii) the connector's expanding sleeves element; and (iii) the connector's mechanical anchorage element. The characteristics of these elements are determined on the basis of piecewise functions, accounting for basic geometrical and mechanical properties such as the strength of the concrete applied to the tube, the connection clamping length, and the size and class of the blind-bolt's internal bolt. An assembly process is then detailed to establish the model for the elastic and inelastic behaviour of the component. Comparisons of model predictions with experimental data show that the proposed model can predict with sufficient accuracy the response of the component. The model furthers the development of a full and detailed design method for an original connection technology.

한국산의 죽류에 관한 연구 (제5보) Phyllotachys reticulata(참대)의 연령식별법에 대하여

  • 정현배
    • Journal of Plant Biology
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    • v.5 no.2
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    • pp.13-16
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    • 1962
  • Without annual ring, the bamboo can not measured by ordinary mensuration method. Other methods yet tried failed to prove the reliability. That means, as often pointed out, that the bamboo lumbering (including forest management) is not free from being precarious. Noting the fact, this author performed a serieds of comparative observations on a group of bamboos in different stages of growth in order to find out if there is any surer mensurability. A conclusion has been reached that the external feature of joints of branch has close connection with the age of bamboo, that the joints of the third major branch counting from the ground have, as shown in the first table, the most probability, its mean being 94.3 per cent, and that those in ages of 3 to 5 have the probability of 100 per cent, showing the far greater accuracy as compared with those in older ages. The above conclusion needs to be adjusted with the following findings; 1) When observed disregarding the joint-tongue(the remainder of the preceeding year's sheath), the major branches show no better probability than the minor ones. 54 to 78 per cent of them shows no difference between them. Probability is averaged by 60 per cent. 2) When in spring the old sheaths drop away from the joints, the new ones sprout out in their places and consequently the joints present an appearance of a kind of joint-ring. But since this joint-ring does not always exactly represent the plant age, some other method must be sought after to count the age. This author noticed what is called "joint-tongue" the tongue-like part of triangle shape which remains at the base of the sheath of the fallen leaf. A fact was ascertained that when the number of the joint-ring coincides with that of the remaining joint-tongue, it exactly indicates the age of the plant.the plant.

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