• Title/Summary/Keyword: ACI model

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Sharing Ship Design Model Based on STEP methodology (STEP 방법론을 이용한 선박설계 모델의 공유)

  • Yong-Jae Shin;Soon-Hung Han
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.4
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    • pp.98-108
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    • 1998
  • Hull design data is currently prepared by a 2D CAD system and re-input to 3D CAD systems specialized for detail design or to a structural analysis system. In this paper, sharing design data among different CAD systems has been studied. Based on STEP methodology, a neutral model is generated from 2D AutoCAD drawings. To handle a geometric data of this model, the non-manifold model of ACIS is used because it can support various CAD data representation such as 2D graphic entities, 3D wireframe, 3D surface model, and solid B-Rep/CSG model. It is observed that a mon-manifold model can easily be transformed to a 3-D wireframe model for the hull detail design system AutoDef or a FE model for the structural analysis system Nastran.

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An artificial intelligence-based design model for circular CFST stub columns under axial load

  • Ipek, Suleyman;Erdogan, Aysegul;Guneyisi, Esra Mete
    • Steel and Composite Structures
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    • v.44 no.1
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    • pp.119-139
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    • 2022
  • This paper aims to use the artificial intelligence approach to develop a new model for predicting the ultimate axial strength of the circular concrete-filled steel tubular (CFST) stub columns. For this, the results of 314 experimentally tested circular CFST stub columns were employed in the generation of the design model. Since the influence of the column diameter, steel tube thickness, concrete compressive strength, steel tube yield strength, and column length on the ultimate axial strengths of columns were investigated in these experimental studies, here, in the development of the design model, these variables were taken into account as input parameters. The model was developed using the backpropagation algorithm named Bayesian Regularization. The accuracy, reliability, and consistency of the developed model were evaluated statistically, and also the design formulae given in the codes (EC4, ACI, AS, AIJ, and AISC) and the previous empirical formulations proposed by other researchers were used for the validation and comparison purposes. Based on this evaluation, it can be expressed that the developed design model has a strong and reliable prediction performance with a considerably high coefficient of determination (R-squared) value of 0.9994 and a low average percent error of 4.61. Besides, the sensitivity of the developed model was also monitored in terms of dimensional properties of columns and mechanical characteristics of materials. As a consequence, it can be stated that for the design of the ultimate axial capacity of the circular CFST stub columns, a novel artificial intelligence-based design model with a good and robust prediction performance was proposed herein.

Indeterminate Strut-Tie Model and Load Distribution Ratio of Continuous RC Deep Beams (II) Validity Evaluation (연속지지 RC 깊은 보의 부정정 스트럿-타이 모델 및 하중분배율 (II) 적합성 평가)

  • Chae, Hyun-Soo;Kim, Byung-Hun;Yun, Young-Mook
    • Journal of the Korea Concrete Institute
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    • v.23 no.1
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    • pp.13-22
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    • 2011
  • In this study, ultimate strengths of 51 continuous reinforced concrete deep beams were evaluated by the ACI 318M-08's strut-tie model approach implemented with the presented indeterminate strut-tie model and load distribution ratio of the companion paper. The ultimate strengths of the continuous deep beams were also estimated by the shear equations derived based on experimental results, conventional design codes based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the presented strut-tie model and load distribution ratio was examined through the comparison of the strength analysis results classified according to the primary design variables of shear span-to-effective depth ratio, flexural reinforcement ratio, and concrete compressive strength. The present study results of ultimate strengths obtained using the indeterminate strut-tie model and load distribution ratio of the continuous deep beams agree fairly well with those obtained using other approaches. In addition, the present approach reflected the effect of the primary design variables on the ultimate strengths of the continuous deep beams consistently and accurately. Therefore, the present study will help structural designers to conduct rational and practical strut-tie model designs of continuous deep beams.

Creep and Shrinkage Strain and Comparative Analysis Between Concrete Test and Experimental Results of Lotte Super Tower (잠실제2롯데월드용 고강도 콘크리트 크리프 및 건조수축 실험결과 및 예측결과 비교분석)

  • Cha, Han-Il;Moon, Hyung-Jae;Seok, Won-Kyun;Park, Soon-Jeon;Lee, Joo-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.309-310
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    • 2009
  • This study was performed as the first step of concrete materiaI research(concrete test program)of Lotte Super Tower column shortening research. Total 18 month's creep and shrinkage results were obtained from the test so far. The analysis were conducted using those results by design strength and loading age, and then validated model and equation were proposed from the result analysis and regression analysis. AC I209R Model, Bazant-Baweja B3 Model, CEB MC99 Model, & GL2000 Model, were employed for this study. The main analysis was completed on the total shrinkage strain and compliance.

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A new statistical approach for joint shear strength determination of RC beam-column connections subjected to lateral earthquake loading

  • Kim, Jaehong;LaFavet, James M.;Song, Junho
    • Structural Engineering and Mechanics
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    • v.27 no.4
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    • pp.439-456
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    • 2007
  • Reinforced concrete (RC) joint shear strength models are constructed using an experimental database in conjunction with a Bayesian parameter estimation method. The experimental database consists of RC beam-column connection test subassemblies that maintained proper confinement within the joint panel. All included test subassemblies were subjected to quasi-static cyclic lateral loading and eventually experienced joint shear failure (either in conjunction with or without yielding of beam reinforcement); subassemblies with out-of-plane members and/or eccentricity between the beam(s) and the column are not included in this study. Three types of joint shear strength models are developed. The first model considers all possible influence parameters on joint shear strength. The second model contains those parameters left after a step-wise process that systematically identifies and removes the least important parameters affecting RC joint shear strength. The third model simplifies the second model for convenient application in practical design. All three models are unbiased and show similar levels of scatter. Finally, the improved performance of the simplified model for design is identified by comparison with the current ACI 352R-02 RC joint shear strength model.

Uncertainty and Sensitivity Analysis of Time-Dependent Deformation in Prestressed Concrete Box Girder Bridges (프리스트레스트 콘크리트 박스 거더 교량의 시간에 따른 변형의 확률 해석 및 민감도 해석)

  • 오병환;양인환
    • Magazine of the Korea Concrete Institute
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    • v.10 no.6
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    • pp.149-159
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    • 1998
  • The reasonable prediction of time-dependent deformation of prestressed concrete(PSC) box girder bridges is very important for accurate construction as well as good serviceability. The long-term behavior is mostly influenced by the probabilistic characteristic of creep and shrinkage. This paper presents a method of statistical analysis and sensitivity analysis of creep and shrinkage effects in PSC box been taken into account - model uncertainty, parameter variation and environmental condition. The statistical and sensitivity analyses are performed by using the numerical simulation of Latin Hypercube sampling. For each sample, the time-dependent structural analysis is performed to produce response data, which are then statistically analyzed. The probabilistic prediction of the confidence limits on long-term effects of creep and shrinkage is then expressed. Three measure are examined to quantify the sensitivity of the outputs of each of the input variables. These are rank correlation coefficient(RCC), partical rank correlation coefficient(PRCC) and standardiozed rank regression coefficient(SRRC) computed on the ranks of the observations. Three creep and shrinkage models - i. e., ACI model. CEB-FIP model and the model in Korea Highway Bridge Specification - are studied. The creep model uncertainy factor and the relative humidity appear to be the most dominant factors with regard to the model output uncertainty.

Neuro-fuzzy optimisation to model the phenomenon of failure by punching of a slab-column connection without shear reinforcement

  • Hafidi, Mariam;Kharchi, Fattoum;Lefkir, Abdelouhab
    • Structural Engineering and Mechanics
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    • v.47 no.5
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    • pp.679-700
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    • 2013
  • Two new predictive design methods are presented in this study. The first is a hybrid method, called neuro-fuzzy, based on neural networks with fuzzy learning. A total of 280 experimental datasets obtained from the literature concerning concentric punching shear tests of reinforced concrete slab-column connections without shear reinforcement were used to test the model (194 for experimentation and 86 for validation) and were endorsed by statistical validation criteria. The punching shear strength predicted by the neuro-fuzzy model was compared with those predicted by current models of punching shear, widely used in the design practice, such as ACI 318-08, SIA262 and CBA93. The neuro-fuzzy model showed high predictive accuracy of resistance to punching according to all of the relevant codes. A second, more user-friendly design method is presented based on a predictive linear regression model that supports all the geometric and material parameters involved in predicting punching shear. Despite its simplicity, this formulation showed accuracy equivalent to that of the neuro-fuzzy model.

Development of Drying Shrinkage Model for HPC Based on Degree of Hydration by CEMHYD-3D Calculation Result (CEMHYD-3D로 예측된 수화도를 기초로 한 고성능 콘크리트의 건조수축 모델제안)

  • Kim Jae Ki;Seo Jong-Myeong;Yoon Young-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.501-504
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    • 2004
  • This paper proposes degree of hydration based shrinkage prediction model of 40MPa HPC. This model shows degree of hydration which is defined as the ratio between the hydrated cement mass and the initial mass of cement is very closely related to shrinkage deformation. In this study, degree of hydration was determined by CEMHYD-3D program of NIST. Verification of the predicted degree of hydration is performed by comparison between test results of compressive strength and estimated one by CEMHYD-3D. Proposed model is determined by statistical nonlinear analysis using the program Origin of Origin Lab. Co. To get coefficients of the model, drying shrinkage tests of four specimen series were followed with basic material tests. Testes were performed in constant temperature /humidity chamber, with difference moisture curing ages to know initial curing time effect. Verification with another specimen, collected construction field of FCM bridge, was given in the same condition as pre-tested specimens. Finally, all test results were compared to propose degree of hydration based model and other code models; AASHTO, ACI, CEB-FIP, JSCE, etc.

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A unified approach to shear and torsion in reinforced concrete

  • Rahal, Khaldoun N.
    • Structural Engineering and Mechanics
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    • v.77 no.5
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    • pp.691-703
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    • 2021
  • Reinforced concrete (RC) beams can be subjected to a complex combination of shear forces (V), torsional moments (T), flexural moments (M) and axial loads (N). This paper proposes a unified approach for the analysis of these elements. An existing model for the analysis of orthogonally reinforced concrete membrane elements subjected to in-plane shear and normal stresses is generalized to apply to the case of beams subjected to the complex loading. The combination of V and T can be critical. Torsion is modelled using the hollow-tube analogy. A direct equation for the calculation of the thickness of the equivalent hollow tube is proposed, and the shear stresses caused by V and T are combined using a simple approach. The development and the evaluation of the model are described. The calculations of the model are compared to experimental data from 350 beams subjected to various combinations of stress-resultants and to the calculations of the ACI and the CSA codes. The proposed model provides the most favorable results. It is also shown that it can accurately model the interaction between V and T. The proposed model provides a unified treatment of shear in beams subjected to complex stress-resultants and in thin membrane elements subjected to in-plane stresses.

Model Equation for Shear Strength of Reinforced Concrete Beams without Web Reinforcement (전단보강근이 없는 철근콘크리트 보의 전단강도 예측 모델식 제안)

  • 김진근;박연동
    • Proceedings of the Korea Concrete Institute Conference
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    • 1993.04a
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    • pp.124-129
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    • 1993
  • In this study, a simple and accurate model equation for prediction of shear strength of reinforce concrete beams without web, reinforcement is proposed based on basic shear transfer mechanism and modified Bazant's size effect law. The proposed equation includes the effects of concrete strength, longitudinal steel ratio, shear span to depth ratio and effective depth. Comparisons with published experimental data indicate that the proposed equation estimates properly the effects of these factors. Among many equations, ACI code equation, Zsutty's equation and Bazant's equation are selected for comparison. As the result, the accuracy of the proposed equation is better than that of any other equations.

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