• Title/Summary/Keyword: Model RC structure

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Site-response effects on RC buildings isolated by triple concave friction pendulum bearings

  • Ates, Sevket;Yurdakul, Muhammet
    • Computers and Concrete
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    • v.8 no.6
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    • pp.693-715
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    • 2011
  • The main object of this study is to evaluate the seismic response effects on a reinforced concrete building isolated by triple concave friction pendulum (TCFP) bearings. The site-response effects arise from the difference in the local soil conditions at the support points of the buildings. The local soil conditions are, therefore, considered as soft, medium and firm; separately. The results on the responses of the isolated building are compared with those of the non-isolated. The building model used in the time history analysis, which is a two-dimensional and eight-storey reinforced concrete building with and without the seismic isolation bearings and/or the local soil conditions, is composed of two-dimensional moment resisting frames for superstructure and of plane elements featuring plane-stress for substructure. The TCFP bearings for isolating the building are modelled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. In order to investigate the efficiency of both the seismic isolation bearings and the site-response effects on the buildings, the time history analyses are elaborately conducted. It is noted that the site-response effects are important for the isolated building constructed on soft, medium or firm type local foundation soil. The results of the analysis demonstrate that the site-response has significant effects on the response values of the structure-seismic isolation-foundation soil system.

Non-linear aero-elastic response of a multi-layer TPS

  • Pasolini, P.;Dowell, E.H.;Rosa, S. De;Franco, F.;Savino, R.
    • Advances in aircraft and spacecraft science
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    • v.4 no.4
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    • pp.449-465
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    • 2017
  • The aim of the present work is to present a computational study of the non-linear aero-elastic behavior of a multi-layered Thermal Protection System (TPS). The severity of atmospheric re-entry conditions is due to the combination of high temperatures, high pressures and high velocities, and thus the aero-elastic behavior of flexible structures can be difficult to assess. In order to validate the specific computational model and the overall strategy for structural and aerodynamics analyses of flexible structures, the simplified TPS sample tested in the 8' High Temperature Tunnel (HTT) at NASA LaRC has been selected as a baseline for the validation of the present work. The von $K{\acute{a}}rm{\acute{a}}n^{\prime}s$ three dimensional large deflection theory for the structure and a hybrid Raleigh-Ritz-Galerkin approach, combined with the first order Piston Theory to describe the aerodynamic flow, have been used to derive the equations of motion. The paper shows that a good description of the physical behavior of the fabric is possible with the proposed approach. The model is further applied to investigate structural and aero-elastic influence of the number of the layers and the stitching pattern.

A Mixed SOC Estimation Algorithm with High Accuracy in Various Driving Patterns of EVs

  • Lim, Dong-Jin;Ahn, Jung-Hoon;Kim, Dong-Hee;Lee, Byoung Kuk
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.27-37
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    • 2016
  • In this paper, a mixed algorithm is proposed to overcome the limitations of the conventional algorithms, which cannot be applied in various driving patterns of drivers. The proposed algorithm based on the coulomb counting method is mixed with reset algorithms that consist of the enhanced OCV reset method and the DCIR iterative calculation method. It has many advantages, such as a simple model structure, low computational overload in various profiles, and a low accumulated SOC error through the frequent SOC reset. In addition, the enhanced parameter based on a mathematical analysis of the second-order RC ladder model is calculated and is then applied to all of the methods. The proposed algorithm is verified by experimental results based on a 27-Ah LiPB. It is observed that the SOC RMSE of the proposed algorithm decreases by about 9.16% compared to the coulomb counting method.

Cost-based optimization of shear capacity in fiber reinforced concrete beams using machine learning

  • Nassif, Nadia;Al-Sadoon, Zaid A.;Hamad, Khaled;Altoubat, Salah
    • Structural Engineering and Mechanics
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    • v.83 no.5
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    • pp.671-680
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    • 2022
  • The shear capacity of beams is an essential parameter in designing beams carrying shear loads. Precise estimation of the ultimate shear capacity typically requires comprehensive calculation methods. For steel fiber reinforced concrete (SFRC) beams, traditional design methods may not accurately predict the interaction between different parameters affecting ultimate shear capacity. In this study, artificial neural network (ANN) modeling was utilized to predict the ultimate shear capacity of SFRC beams using ten input parameters. The results demonstrated that the ANN with 30 neurons had the best performance based on the values of root mean square error (RMSE) and coefficient of determination (R2) compared to other ANN models with different neurons. Analysis of the ANN model has shown that the clear shear span to depth ratio significantly affects the predicted ultimate shear capacity, followed by the reinforcement steel tensile strength and steel fiber tensile strength. Moreover, a Genetic Algorithm (GA) was used to optimize the ANN model's input parameters, resulting in the least cost for the SFRC beams. Results have shown that SFRC beams' cost increased with the clear span to depth ratio. Increasing the clear span to depth ratio has increased the depth, height, steel, and fiber ratio needed to support the SFRC beams against shear failures. This study approach is considered among the earliest in the field of SFRC.

Two scale seismic analysis of masonry infill concrete frames through hybrid simulation

  • Cesar Paniagua Lovera;Gustavo Ayala Milian
    • Earthquakes and Structures
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    • v.24 no.6
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    • pp.393-404
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    • 2023
  • This paper presents the application of hybrid-simulation-based adapter elements for the non-linear two-scale analysis of reinforced concrete frames with masonry infills under seismic-like demands. The approach provides communication and distribution of the computations carried out by two or more remote or locally distributed numerical models connected through the OpenFresco Framework. The modeling consists of a global analysis formed by macro-elements to represent frames and walls, and to reduce global degrees of freedom, portions of the structure that require advanced analysis are substituted by experimental elements and dimensional couplings acting as interfaces with their respective sub-assemblies. The local sub-assemblies are modeled by solid finite elements where the non-linear behavior of concrete matrix and masonry infill adopt a continuum damage representation and the reinforcement steel a discrete one, the conditions at interfaces between concrete and masonry are considered through a contact model. The methodology is illustrated through the analysis of a frame-wall system subjected to lateral loads comparing the results of using macro-elements, finite element model and experimental observations. Finally, to further assess and validate the methodology proposed, the paper presents the pushover analysis of two more complex structures applying both modeling scales to obtain their corresponding capacity curves.

Analytical Method on PSC I Girder with Strengthening of External Tendon (외부강선으로 보강되는 PSC I 합성거더의 해석 기법)

  • Park, Jae-Guen;Lee, Byeong-Ju;Kim, Moon-Young;Shin, Hyun-Mock
    • Journal of the Korea Concrete Institute
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    • v.20 no.6
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    • pp.697-704
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    • 2008
  • This paper presents an analytical prediction of Nonlinear characteristics of prestressed concrete bridges by strengthened of externally tendon considering construction sequence, using unbonded tendon element and beam-column element based on flexibility method. Unbonded tendon model can represent unbounded tendon behavior in concrete of PSC structures and it can deal with the prestressing transfer of posttensioned structures and calculate prestressed concrete structures more efficiently. This tendon model made up the several nodes and segment, therefore a real tendon of same geometry in the prestressed concrete structure can be simulated the one element. The beam-column element was developed with reinforced concrete material nonlinearities which are based on the smeared crack concept. The fiber hysteresis rule of beam-column element is derived from the uniaxial constitutive relations of concrete and reinforcing steel fibers. The formulation of beam-column element is based on flexibility. Beam-column element and unbonded tendon element were be involved in A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), that were used the analysis of RC and PSC structures. The proposed numerical method for prestressed concrete structures by strengthened of externally tendon is verified by comparison with reliable experimental results.

Inelastic Dynamic Demands of a RC Special Moment Frame Building (철근 콘크리트 특수 모멘트 골조 건물의 비탄성 동적 요구값)

  • Kim, Tae-Wan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.9 no.5 s.45
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    • pp.11-19
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    • 2005
  • Seismic design of a building is usually performed by using the linear static procedure. However, the actual behavior of the building subjected to earthquake is inelastic and dynamic in nature. Therefore, inelastic dynamic analysis is required to evaluate the safety of the structure designed by the current design codes. For the validation, a RC special moment resisting frame building was chosen and designed by IBC 2003 representing new codes. Maximum plastic rotation and dissipated energy of some selected members were calculated for examining if the inelastic behavior of the building follows the intention of the code, and drift demand were calculated as well for checking if the building well satisfies the design drift limit. In addition, the effect of including internal moment resisting frames (non lateral resisting system) on analyses results was investigated. As a result of this study, the building designed by IBC 2003 showed the inelastic behavior intended in the code and satisfied the design drift limit. Furthermore, the internal moment resisting frames should be included in the analytical model as they affect the results of seismic analyses significantly.

Optimization of Radar Absorbing Structures for Aircraft Wing Leading Edge (항공기 날개 앞전의 레이더흡수구조 최적화)

  • Jang, Byung-Wook;Park, Sun-Hwa;Lee, Won-Jun;Joo, Young-Sik;Park, Jung-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.4
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    • pp.268-274
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    • 2013
  • In this paper, objective functions are defined for optimization of radar absorbing structures (RAS) on the aircraft wing leading edge. RAS is regarded as a single layer structure made of dielectrics. Design variables are the real and imaginary parts of complex permittivity. Reflection coefficient(RC) and radar cross section(RCS) are used in the objective function respectively. Transmission line theory is employed to calculate the RC. The RCS is evaluated by using physical optics(PO) for a leading edge part model. Genetic algorithm(GA) is used to perform optimization procedures. The radar absorbing performance of designed RAS is assessed by the RCS of a wing which has RAS on the leading edge.

Experiment on Flexural Analysis of RC Beams Strengthened with Composite Material Panel (복합재료 패널로 보강된 철근 콘크리트 보의 휨 실험)

  • Kim, Jin-Man;Jung, Mi-Roo;Lee, Jae-Hong;Yoon, Kwang-Sup
    • Journal of Korean Association for Spatial Structures
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    • v.10 no.2
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    • pp.117-126
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    • 2010
  • Experiment on flexural analysis of RC beams strengthened with composite material panel is presented. Recently, the strengthening of reinforced concrete structures using advanced fiber reinforced plastic (FRP) composites, and in particular the behavior of FRP-reinforced concrete structure is topic that has become very popular because of good corrosion resistance and easy for site handling due to their light weight. In this study, an efficient computational analysis using ABAQUS to predict the ultimate moment capacity of reinforced concrete beams strengthened with FRP is presented. Test parameters in this study are the shape of fiber arrangement (LT, DB, DBT) and the number of carbon fiber sheets (2ply, 3ply). When comparing with results of the analytical model, results of the experiments show similar values. Furthermore, reinforced concrete beam with FRP obtains improved effects for ultimate strength.

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Experimental research on the propagation of plastic hinge length for multi-scale reinforced concrete columns under cyclic loading

  • Tang, Zhenyun;Ma, Hua;Guo, Jun;Xie, Yongping;Li, Zhenbao
    • Earthquakes and Structures
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    • v.11 no.5
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    • pp.823-840
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    • 2016
  • The plastic hinge lengths of beams and columns are a critical demand parameter in the nonlinear analysis of structures using the finite element method. The numerical model of a plastic hinge plays an important role in evaluating the response and damage of a structure to earthquakes or other loads causing the formation of plastic hinges. Previous research demonstrates that the plastic hinge length of reinforced concrete (RC) columns is closely related to section size, reinforcement ratio, reinforcement strength, concrete strength, axial compression ratio, and so on. However, because of the limitations of testing facilities, there is a lack of experimental data on columns with large section sizes and high axial compression ratios. In this work, we conducted a series of quasi-static tests for columns with large section sizes (up to 700 mm) and high axial compression ratios (up to 0.6) to explore the propagation of plastic hinge length during the whole loading process. The experimental results show that besides these parameters mentioned in previous work, the plastic hinge of RC columns is also affected by loading amplitude and size effect. Therefore, an approach toward considering the effect of these two parameters is discussed in this work.