• Title, Summary, Keyword: Beam-Spring Model

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Prediction of Nonlinear Shear Behavior of Reinforced Concrete Beam-Column Joints (철근콘크리트 보-기둥 접합부의 비선형 전단거동예측)

  • Cho, Chang-Geun;Woo, Sung-Woo
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.2
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    • pp.29-36
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    • 2009
  • The present study emphasizes a nonlinear model to predict the shear behaviour of reinforced concrete interior beam-column joints. To model the shear behaviour of a panel zone in the beam-column joint, a modified softened truss model theory for in-plane shear prediction was introduced. This relationship was changed to define the characteristics for the rotational spring to represent the shear deformation in the joint by an equivalent moment-rotation relationship from the joint equilibrium. The analysis model was compared with experiments on reinforced concrete interior beam-column joints that were subjected to axial and shear forces, and the current model was found to accurately predict not only the shear force but also the shear deformation in the joint.

Evaluating the accuracy of a new nonlinear reinforced concrete beam-column element comprising joint flexibility

  • Izadpanah, Mehdi;Habibi, AliReza
    • Earthquakes and Structures
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    • v.14 no.6
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    • pp.525-535
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    • 2018
  • This study presents a new beam-column model comprising material nonlinearity and joint flexibility to predict the nonlinear response of reinforced concrete structures. The nonlinear behavior of connections has an outstanding role on the nonlinear response of reinforced concrete structures. In presented research, the joint flexibility is considered applying a rotational spring at each end of the member. To derive the moment-rotation behavior of beam-column connections, the relative rotations produced by the relative slip of flexural reinforcement in the joint and the flexural cracking of the beam end are taken into consideration. Furthermore, the considered spread plasticity model, unlike the previous models that have been developed based on the linear moment distribution subjected to lateral loads includes both lateral and gravity load effects, simultaneously. To confirm the accuracy of the proposed methodology, a simply-supported test beam and three reinforced concrete frames are considered. Pushover and nonlinear dynamic analysis of three numerical examples are performed. In these examples the nonlinear behavior of connections and the material nonlinearity using the proposed methodology and also linear flexibility model with different number of elements for each member and fiber based distributed plasticity model with different number of integration points are simulated. Comparing the results of the proposed methodology with those of the aforementioned models describes that suggested model that only uses one element for each member can appropriately estimate the nonlinear behavior of reinforced concrete structures.

Simulation of cyclic response of precast concrete beam-column joints

  • Adibi, Mahdi;Talebkhah, Roozbeh;Yahyaabadi, Aliakbar
    • Computers and Concrete
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    • v.24 no.3
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    • pp.223-236
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    • 2019
  • Experience of previous earthquakes shows that a considerable portion of concrete precast buildings sustain relatively large damages especially at the beam-column joints where the damages are mostly caused by bar slippage. Precast concrete buildings have a kind of discontinuity in their beam-column joints, so reinforcement details in this area is too important and have a significant effect on the seismic behavior of these structures. In this study, a relatively simple and efficient nonlinear model is proposed to simulate pre- and post-elastic behavior of the joints in usual practice of precast concrete building. In this model, beam and column components are represented by linear elastic elements, dimensions of the joint panel are defined by rigid elements, and effect of slip is taken into account by a nonlinear rotational spring at the end of the beam. The proposed method is validated by experimental results for both internal and external joints. In addition, the seismic behavior of the precast building damaged during Bojnord earthquake 13 May 2017, is investigated by using the proposed model for the beam-column joints. Damage unexpectedly inducing the precast building in the moderate Bojnord earthquake may confirm that bearing capacity of the precast building was underestimated without consideration of joint behavior effect.

A study on the Modeling and Dynamic Analysis of Cracked Beam Structures (균열이 있는 보의 모델링 및 동적 해석에 관한 연구)

  • 홍성욱;김만달;이종원
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.6
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    • pp.197-204
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    • 2003
  • This paper presents an efficient modeling and dynamic analysis method for open cracked beam structures. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed method adopts the exact dynamic element method (EDEM) to avoid the inconvenience and numerical errors in association with re-meshing the structural model with the crack position changed. The proposed modeling method is validated through a series of simulation and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, two kinds of experiments are performed to validate the proposed modeling method. Finally, a diagnostic scheme fur open cracked beam structures is proposed and demonstrated through a numerical example.

Numerical study for vibration response of concrete beams reinforced by nanoparticles

  • Heidari, Ali;Keikha, Reza;Haghighi, Mohammad Salkhordeh;Hosseinabadi, Hamidreza
    • Structural Engineering and Mechanics
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    • v.67 no.3
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    • pp.311-316
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    • 2018
  • Vibration of concrete beams reinforced by agglomerated silicon dioxide ($SiO_2$) nanoparticles is studied based on numerical methods. The structure is simulated by Euler-Bernoulli beam model and the Mori-Tanaka model is used for obtaining the effective material properties of the structure. The concrete beam is located in soil medium which is modeled by spring elements. The motion equations are derived based on energy method and Hamilton's principle. Based on exact solution, the frequency of the structure is calculated. The effects of different parameters such as volume percent of $SiO_2$ nanoparticles and agglomeration, soil medium and geometrical parameters of beam are shown on the frequency of system. The results show that with increasing the volume percent of $SiO_2$ nanoparticles, the frequency increases.

Dynamic Analysis of the Cracked Timoshenko Beam under a Moving Mass using Finite Element Method (유한요소법을 이용한 이동질량 하에 크랙을 갖는 티모센코 보의 동특성 연구)

  • Kang Hwan-Jun;Lee Shi-Bok;Hong Keum-Shik;Jeon Seung-Min
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.271-276
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    • 2004
  • In this paper. dynamic behavior of the cracked beam under a moving mass is presented using the finite element method (FEM). Model accuracy is improved with the following consideration: (1) FE model with Timoshenko beam element (2) Additional flexibility matrix due to crack presence (3) Interaction forces between the moving mass and supported beam. The Timoshenko bean model with a two-node finite element is constructed based on Guyan condensation that leads to the results of classical formulations. but in a simple and systematic manner. The cracked section is represented by local flexibility matrix connecting two unchanged beam segments and the crack as modeled a massless rotational spring. The inertia force due to the moving mass is also involved with gravity force equivalent to a moving load. The numerical tests for various mass levels. crack sizes. locations and boundary conditions were performed.

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Flexural Behavior of Steel Composite Beam with Built-up Cross-section Considering Bolt Deformation (볼트의 변형을 고려한 강재 조립 합성보의 휨거동)

  • Kim, Sung-Bo;Kim, Hun-Kyom;Jung, Kyoung-Hwan;Han, Man-Yop;Kim, Moon-Young
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.21 no.1
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    • pp.43-50
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    • 2008
  • The analysis and results of flexural behavior for steel composite beam with built-up cross-section considering bolt deformation are presented in this paper. The bolt deformation and the restrict effect due to bolt-connection and friction are considered to investigate the flexural behavior of steel composite beam. Nonlinear spring element in ABAQUS is used to consider bolt deformation, also the results are compared with those in case bolt deformations are ignored. The displacement, bending stresses and shear stresses are calculated by F.E. model, and these results are compared with the analytical value of no interaction beam, partial interaction beam and full interaction beam. As a result of analysis, the behavior of composite beam is more dependant on the composite rate than the friction of the steel. When the composite rate is more than 50%, the behavior of composite beam considering the effects of bolt deformation is similar to that of fully composite beam.

The development of a back analysis program for subsea tunnel stability under operation: longitudinal direction (운영 중 해저 터널의 안정성 평가를 위한 역해석 프로그램 개발: 종단방향)

  • An, Joon-Sang;Kim, Byung-Chan;Moon, Hyun-Koo;Song, Ki-Il
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.6
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    • pp.545-556
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    • 2016
  • If a back analysis is used in various measurement information for the estimation of an operating subsea tunnel safety, it is possible to obtain the results within efficient error rate. With such a commercial geotechnical analysis program as FLAC3D, back analysis is performed with a DEA which was validated in previous studies. However, there is a problem that is relatively a time-consuming analysis. For this reason, beam-spring model-based FEM solver which takes shorter relative analysis time, was developed by Python language, and then combined with the built-DEA. In order to consider the assessment of safety of an operation tunnel near real-time, a program for longitudinal direction tunnel was developed due to its relative easy development for analysis solver engine.

Reliability analysis-based conjugate map of beams reinforced by ZnO nanoparticles using sinusoidal shear deformation theory

  • Keshtegar, Behrooz;Kolahchi, Reza
    • Steel and Composite Structures
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    • v.28 no.2
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    • pp.195-207
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    • 2018
  • First-order reliability method (FORM) is enhanced based on the search direction using relaxed conjugate reliability (RCR) approach for the embedded nanocomposite beam under buckling failure mode. The RCR method is formulated using discrete conjugate map with a limited scalar factor. A dynamical relaxed factor is proposed to control instability of proposed RCR, which is adjusted using sufficient descent condition. The characteristic of equivalent materials for nanocomposite beam are obtained by micro-electro-mechanical model. The probabilistic model of nanocomposite beam is simulated using the sinusoidal shear deformation theory (SSDT). The beam is subjected to external applied voltage in thickness direction and the surrounding elastic medium is modeled by Pasternak foundation. The governing equations are derived in terms of energy method and Hamilton's principal. Using exact solution, the implicit buckling limit state function of nanocomposite beam is proposed, which is involved various random variables including thickness of beam, length of beam, spring constant of foundation, shear constant of foundation, applied voltage, and volume fraction of ZnO nanoparticles in polymer. The robustness, accuracy and efficiency of proposed RCR method are evaluated for this engineering structural reliability problem. The results demonstrate that proposed RCR method is more accurate and robust than the excising reliability methods-based FORM. The volume fraction of ZnO nanoparticles and the applied voltage are the sensitive variables on the reliable levels of the nanocomposite beams.

A modified RBSM for simulating the failure process of RC structures

  • Zhao, Chao;Zhong, Xingu;Liu, Bo;Shu, Xiaojuan;Shen, Mingyan
    • Computers and Concrete
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    • v.21 no.2
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    • pp.219-229
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    • 2018
  • In this paper, a modified rigid body spring model (RBSM) is proposed and used to analyze the damage and failure process of reinforced concrete (RC) structures. In the proposed model, the concrete is represented by an assembly of rigid blocks connected with a uniform distribution of normal and tangential springs to simulate the macroscopic mechanical behavior of concrete. Steel bars are evenly dispersed into rigid blocks as a kind of homogeneous axial material, and an additional uniform distribution of axial and dowel springs is defined to consider the axial stiffness and dowel action of steel bars. Perfect bond between the concrete and steel bars is assumed, and tension stiffening effect of steel bars is modeled by adjusting the constitutive relationship for the tensile reinforcement. Adjacent blocks are allowed to separate at the contact interface, which makes it convenient and easy to simulate the cracking process of concrete. The failure of the springs is determined by the Mohr-Coulomb type criterion with the tension and compression caps. The effectiveness of the proposed method is confirmed by elastic analyses of a cantilever beam under different loading conditions and failure analyses of a RC beam under two-point loading.