Behaviors of box-shape steel reinforced concrete composite beam

Yang, Chun,Cai, Jian,Wu, Yi,He, Jiangang,Chen, Haifeng Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.22 No.4

Experimental studies on the behaviors of box-shape steel reinforced concrete (SRC) composite beams were conducted. Seven 1:3 scale model composite beams were tested to failure. Each of the beams was simply supported at the ends and two concentrated loads were applied at the one-third span and two-thirds span respectively. Experimental results indicate that the flexural strength can be enhanced when the ratio of flexural reinforcements and flange thickness of the shape steel are increased; the shear strength is enhanced with increase of web thickness of the shape steel. Insignificant effects of concrete in the box-shape steel are found on improving the flexural strength and shear strength of the box-shape SRC composite beams, thus concrete inside the box-shape steel can be saved, and the weight of the SRC beams can be decreased. Shear studs can strengthen the connection and co-work effects between the shape steel and the concrete and enhance the shear strength, but stud design for the composite beams should be further improved. Formulas for flexural and shear strength of the composite beams are proposed, and the calculated results are in good agreement with the experimental results. In general, the box-shape SRC composite beam is a kind of ductile member, and suitable for extensive engineering application.

Studies on restoring force model of concrete filled steel tubular laced column to composite box-beam connections

Lizhong Jiang,Zhi Huang,Wang-Bao Zhou,Shan Chen 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.6

Mega composite structure systems have been widely used in high rise buildings in China. Compared to other structures, this type of composite structure systems has a larger cross-section with less weight. Concrete filled steel tubular (CFST) laced column to box-beam connections are gaining popularity, in particular for the mega composite structure system in high rise buildings. To enable a better understanding of the destruction characteristics and aseismic performance of these connections, three different connection types of specimens including single-limb bracing, cross bracing and diaphragms for core area of connections were tested under low cyclic and reciprocating loading. Hysteresis curves and skeleton curves were obtained from cyclic loading tests under axial loading. Based on these tested curves, a new trilinear hysteretic restoring force model considering rigidity degradation is proposed for CFST laced column to box-beam connections in a mega composite structure system, including a trilinear skeleton model based on calculation, law of stiffness degradation and hysteresis rules. The trilinear hysteretic restoring force model is compared with the experimental results. The experimental data shows that the new hysteretic restoring force model tallies with the test curves well and can be referenced for elastic-plastic seismic analysis of CFST laced column to composite box-beam connection in a mega composite structure system.

머신 러닝을 이용한 PIC 로봇 암 강성 향상에 대한 연구

지승민 ( Seungmin Ji ),함석우 ( Seokwoo Ham ),전성식 ( Seong S. Cheon ) 한국복합재료학회 2022 Composites research Vol.35 No.5

PIC(Piecewise Integrated Composite)는 적층 복합재의 기계적 특성을 향상시키기 위해 다양한 적층 순서를 모자이크 방식으로 할당하여 복합 구조를 설계하는 새로운 개념이다. 또한 머신 러닝은 인공 지능의 하위 범주로, 컴퓨터가 데이터에서 지속적으로 학습하고 데이터를 기반으로 예측하는 능력을 개발한 다음 추가 프로그래밍 없이 조정하는 과정을 의미한다. 본 연구에서는 구조적 강성을 높이기 위해 기계학습을 기반으로 넓고 얇은 LCD 디스플레이를 운반 및 이송하기 위한 테이퍼 박스형 빔형 PIC 로봇 암이 설계되었다. 필수 학습 데이터는 예비 FE 해석 과정에서 유한 요소 모델 중 의도적으로 배치된 참조 요소에서 수집되었다. 또한 인장, 압축 또는 전단과 같은 지배적인 외부 하중 유형을 판단하기 위해 각 유한 요소에 대한 3축 특성 값을 얻었다. 학습 데이터를 이용하여 머신 러닝 모델을 훈련하고 평가되었으며, 정확도 레벨을 만족한 머신 러닝 모델을 이용해 요소의 로딩 유형을 예측하였다. 특정 하중 유형에 대해 우세한 것으로 알려진 세 가지 유형의 적층 각도 순서가 PIC 로봇 암에 모자이크 방식으로 할당되었습니다. 이후 굽힘형 FE 해석을 수행한 결과 PIC 로봇 암이 기존의 단일 적층 각도 순서로 제작된 복합재 로봇 암에 비해 강성이 증가된 것으로 나타났다. PIC (Piecewise Integrated Composite) is a new concept for designing a composite structure with mosaically assigning various types of stacking sequences in order to improve mechanical properties of laminated composites. Also, machine learning is a sub-category of artificial intelligence, that refers to the process by which computers develop the ability to continuously learn from and make predictions based on data, then make adjustments without further programming. In the present study, the tapered box beam type PIC robot arm for carrying and transferring wide and thin LCD display was designed based on the machine learning in order to increase structural stiffness. Essential training data were collected from the reference elements, which were intentionally designated elements among finite element models, during preliminary FE analysis. Additionally, triaxiality values for each finite element were obtained for judging the dominant external loading type, such as tensile, compressive or shear. Training and evaluating machine learning model were conducted using the training data and loading types of elements were predicted in case the level accuracy was fulfilled. Three types of stacking sequences, which were to be known as robust toward specific loading types, were mosaically assigned to the PIC robot arm. Henceforth, the bending type FE analysis was carried out and its result claimed that the PIC robot arm showed increased stiffness compared to conventional uni-stacking sequence type composite robot arm.

Flexural Decoupling Analysis Method of Composite Box Girder with Corrugated Steel Webs

Zhou Mao-Ding,Zhang Yuan-Hai,Ji Wei 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.1

The existing flexural analysis methods of corrugated steel web composite box girders are either inaccurate due to thoughtlessness of the influencing factors, or complicated due to excessive consideration of the influencing factors. In this study, a flexural displacement model of composite box girder considering both the accordion effect and shear deformation of web and the shear lag effect of flange is proposed. According to the internal force balance condition, the complex flexural models of a composite box girder are decoupled into three independent simple flexural states: Euler–Bernoulli beam flexure satisfying the quasi-plane assumption, flexure of equivalent web deformation, and flexure of shear lag of flange. Based on the flexural theory of the thin-walled beam, the generalized internal force system and beam-type finite element model was established corresponding to each flexural state. The results of numerical examples show that the proposed method has high solution accuracy and can directly obtain the displacement and internal force of each flexure deformation. The moment results show that the generalized moment has a peak value at the point of shear discontinuity, and increases or decays rapidly near it.

Distortional and local buckling of steel-concrete composite box-beam

Lizhong Jiang,Jingjing Qi,Andrew Scanlon,Linlin Sun 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.3

Distortional and local buckling are important factors that influences the bearing capacity of steel-concrete composite box-beam. Through theoretical analysis of distortional buckling forms, a stability analysis calculation model of composite box beam considering rotation of steel beam top flange is resented. The critical bending moment calculation formula of distortional buckling is established. In addition, mechanical behaviors of a steel beam web in the negative moment zone subjected separately to bending stress, shear stress and combined stress are investigated. Elastic buckling factors of steel web under different stress conditions are calculated. On the basis of local buckling analysis results, a limiting value for height-to thickness ratio of a steel web in the elastic stage is proposed. Numerical examples are presented to verify the proposed models.

복합재료 적층 주익의 정적 공력탄성학 해석

윤남경,신상준 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11

현재 항공기는 그 비행속도 성능의 증가와 주익 구조물의 상대적 유연도의 증대로 인하여 공력탄성학적 현상의 정밀한 예측이 중요하다. 그 중 발산 현상은 항공기 구조물에 치명적인 파괴를 유발하기 때문에 절대적으로 피해야 할 요소이다. 본 논문에서는 단일-셀 또는 이중-셀 구조의 Box-Beam 단면형상을 지닌 주익에 대해서 복합재료의 적층 특성과 날개의 후퇴각이 발산 현상에 주는 영향을 날개 단면해석 프로그램인 UM/VABS 와 다물체 동역학 해석 프로그램인 DYMORE 를 활용하여 정밀 예측하고 그 정밀성을 검증하고자 한다. Aeroelastic problems become important due to the improvement in flight speed performance and increased flexibility of the aircraft structures. Divergence must be avoided because it causes catastrophic failure in an aircraft. In this paper, a composite wing with a box-beam cross-sectional configuration will be investigated regarding its torsional divergence. This phenomenon is generally influenced by the number of the cells in the cross section, such as single-cell or doublecell, and ply angles, wing sweep angle, etc. VABS and multi-body dynamics analysis program, DYMORE will be used and the resulting divergence characteristics will be validated.

Nonlinear Structural Analysis of High-Aspect-Ratio Structures using Large Deflection Beam Theory

Kim, Kyung-Seok,Yoo, Seung-Jae,Lee, In The Korean Society for Aeronautical and Space Scie 2008 International Journal of Aeronautical and Space Sc Vol.9 No.2

The nonlinear structural analyses of high-aspect-ratio structures were performed. For the high-aspect-ratio structures, it is important to understand geometric nonlinearity due to large deflections. To consider geometric nonlinearity, finite element analyses based on the large deflection beam theory were introduced. Comparing experimental data and the present nonlinear analysis results, the current results were proved to be very accurate for the static and dynamic behaviors for both isotropic and anisotropic beams.

Nonlinear Structural Analysis of High-Aspect-Ratio Structures using Large Deflection Beam Theory

Kyung-Seok Kim,Seung-Jae Yoo,In-Gyu Lim,In Lee 한국항공우주학회 2008 International Journal of Aeronautical and Space Sc Vol.9 No.2

The nonlinear structural analyses of high-aspect-ratio structures were performed. For the high-aspect-ratio structures, it is important to understand geometric nonlinearity due to large deflections. To consider geometric nonlinearity, finite element analyses based on the large deflection beam theory were introduced. Comparing experimental data and the present nonlinear analysis results, the current results were proved to be very accurate for the static and dynamic behaviors for both isotropic and anisotropic beams.

Dynamic stiffness matrix of composite box beams

김남일 국제구조공학회 2009 Steel and Composite Structures, An International J Vol.9 No.5

For the spatially coupled free vibration analysis of composite box beams resting on elastic foundation under the axial force, the exact solutions are presented by using the power series method based on the homogeneous form of simultaneous ordinary differential equations. The general vibrational theory for the composite box beam with arbitrary lamination is developed by introducing VlasovΦs ssumption. Next, the equations of motion and force-displacement relationships are derived from the energy principle and explicit expressions for displacement parameters are presented based on power series expansions of displacement components. Finally, the dynamic stiffness matrix is calculated using force-displacement relationships. In addition, the finite element model based on the classical Hermitian interpolation polynomial is presented. To show the performances of the proposed dynamic stiffness matrix of composite box beam, the numerical solutions are presented and compared with the finite element solutions using the Hermitian beam elements and the results from other researchers. Particularly, the effects of the fiber orientation, the axial force, the elastic foundation, and the boundary condition on the vibrational behavior of composite box beam are investigated parametrically. Also the emphasis is given in showing the phenomenon of vibration mode change.

Improved Analytical Method to Investigate the Dynamic Characteristics of Composite Box Beam with Corrugated Webs

Yulin Feng,Lizhong Jiang,Wangbao Zhou 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.1

This study establishes an improved analytical method (IAM) to investigate the dynamic characteristics of composite box beam with corrugated webs (CBBCW), and the IAM has comprehensively considered the eff ects of several factors, such as the shear lag, interfacial slip, shear deformation and rotational inertia of CBBCW in combination with the characteristics of CBBCW. Further, based on the Hamilton principle, the vibration diff erential equation and boundary conditions for CBBCW have been deduced. Finally, an IAM for calculating the dynamic characteristics of CBBCW was proposed. Based on the IAM developed in this study, the natural frequencies of multiple CBBCW cases with diff erent spans, shear connection degrees and boundary conditions have been calculated. The results calculated by the IAM have been compared with those calculated by the fi nite element method and by the general beam theory. The comparison verifi es the eff ectiveness of the IAM and obtains some conclusions that are meaningful to engineering design, i.e. the shear lag eff ect of CBBCW increases with increasing shear connection degree and also increases with increasing order of the vibration mode, the shear lag eff ect of the CBBCW is up to 6.2% in the fi rst fi ve orders of the vibration modes and the eff ect cannot be ignored. In the fi rst- and second-order vibration modes of the CBBCW cases, the maximum interface slip eff ect of CBBCW is 28.42% and therefore cannot be ignored. On the other hand, the shear lag eff ect of CBBCW is usually lower than those of ordinary composite box beam with the same web thickness.