• Title/Summary/Keyword: Hybrid Structures

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The Static Unstable Characteristics of Tensegrity-Type Cable Dome according to the Structural System (구조시스템에 따른 Tensegrity형 케이블 돔의 정적 불안정 거동특성)

  • Cho, In-Ki;Kim, Hyung-Seok;Kim, Seung-Deog;Kang, Moon-Myung
    • Journal of Korean Association for Spatial Structures
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    • v.4 no.3 s.13
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    • pp.65-75
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    • 2004
  • A shell structure, having a curvature with a curved surface, is an extremely efficient mechanical creation regard to the external load. A basic structural resistance mechanism is the structural system, which is resisted the out-of-plane direction load by in-plane forces using the structure's curvature. Therefore, it has a merit to make thin and lightweight large spacial structures using minimum materials. Among the large spare structural system, the rapid development of the membrane structures, cable structures and the hybrid structures are watched recently. But, this kind of structural system shows the unstable phenomenon by snap-through or bifurcation according to the shape of structure, and the understanding of the collapse mechanism by this phenomenon is very important to the design process. In this study, I investigated the unstable characteristics of the Geiger-type, Zetlin-type and flower-type hybrid cable dome structures, which is the lightweight hybrid structures using compression and tension elements continuously, according to the difference of structural system.

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Effect of fabrication processes on mechanical properties of glass fiber reinforced polymer composites for 49 meter (160 foot) recreational yachts

  • Kim, Dave Dae-Wook;Hennigan, Daniel John;Beavers, Kevin Daniel
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.2 no.1
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    • pp.45-56
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    • 2010
  • Polymer composite materials offer high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions that appeal to the marine industry. The advantages of composite construction have led to their incorporation in U.S. yacht hull structures over 46 meters (150 feet) in length. In order to construct even larger hull structures, higher quality composites with lower cost production techniques need to be developed. In this study, the effect of composite hull fabrication processes on mechanical properties of glass fiber reinforced plastic (GFRP) composites is presented. Fabrication techniques investigated during this study are hand lay-up (HL), vacuum infusion (VI), and hybrid (HL+VI) processes. Mechanical property testing includes: tensile, compressive, and ignition loss sample analysis. Results demonstrate that the vacuum pressure implemented dining composite fabrication has an effect on mechanical properties. The VI processed GFRP yields improved mechanical properties in tension/compression strengths and tensile modulus. The hybrid GFRP composites, however, failed in a sequential manor, due to dissimilar failure modes in the HL and VI processed sides. Fractography analysis was conducted to validate the mechanical property testing results.

Experimental and numerical investigations into the composite behaviour of steel frames and precast concrete infill panels with window openings

  • Teeuwen, P.A.;Kleinman, C.S.;Snijder, H.H.;Hofmeyer, H.
    • Steel and Composite Structures
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    • v.10 no.1
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    • pp.1-21
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    • 2010
  • As an alternative for conventional structures for tall buildings, a hybrid lateral load resisting structure has been designed, enabling the assembly of tall buildings directly from a truck. It consists of steel frames with discretely connected precast concrete infill panels provided with window openings. Besides the stiffening and strengthening effect of the infill panels on the frame structure, economical benefits may be derived from saving costs on materials and labour, and from reducing construction time. In order to develop design rules for this type of structure, the hybrid infilled frame has recently been subjected to experimental and numerical analyses. Ten full-scale tests were performed on one-storey, one-bay, 3 by 3 m infilled frame structures, having different window opening geometries. Subsequently, the response of the full-scale experiments was simulated with the finite element program DIANA. The finite element simulations were performed taking into account non-linear material characteristics and geometrical non-linearity. The experiments show that discretely connected precast concrete panels provided with a window opening, can significantly improve the performance of steel frames. A comparison between the full-scale experiments and simulations shows that the finite element models enable simulating the elastic and plastic behaviour of the hybrid infilled frame.

A Study on the Nonlinear Instability Behavior of Hybrid Structures(I) - Characteristic of Static In-Plane Torsional Buckling by Initial Shape Imperfection- (Hybrid 구조물의 비선형 불안정 거동에 관한 연구(I) -초기형상 불완전에 의한 정적 면내비틀림 좌굴 특성-)

  • Kim, Seung Deog;Son, Su Deok;Kim, Hyung Seok;Kang, Moon Myung
    • Journal of Korean Society of Steel Construction
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    • v.13 no.5
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    • pp.587-597
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    • 2001
  • The structural system that discreterized continuous shells is frequently used to make dome-type structures and these structures show the unstable phenomena by snap-through or bifurcation when a load level reaches certain critical value. The characteristic structural behaviour of a cable dome shows a strong nonlinearity and very sensitive according to the initial imperfection. In this study the shape finding problem by applying initial tension stress is investigated and using this the unstable phenomena of perfectly shaped and initially imperfected shape model by external forces are examined to grasp the unstable behavior of cable dome using the Geiger-type model.

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High Efficient Phase Shifters Using Defected Ground Structures (결함 접지 구조를 이용한 고성능 위상 천이기)

  • Han Sang-Min;Kim Chul-Soo;Ahn Dal
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.1 s.104
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    • pp.1-7
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    • 2006
  • New phase shifters with higher phase shift values are presented using defected ground structures(DGSs). The varactor diodes are mounted on DGSs of termination loads to control the large phase variation of the DGS at resonance. Two types of phase shifters are implemented with a branch-line and a coupled line hybrid. The experimental results of the proposed phase shifters show $135\%$ and $221\%$ increases in maximum phase shills, respectively, compared with those of conventional ones.

Active Shape Control of Composite Beam Using Shape Memory Alloy Actuators (형상기억합금 작동기를 이용한 복합재 보의 능동 형상 제어)

  • Yang, Seung-Man;Roh, Jin-Ho;Han, Jae-Hung;Lee, In
    • Composites Research
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    • v.17 no.4
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    • pp.18-24
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    • 2004
  • In this paper, active shape control of composite structures actuated by shape memory alloy (SMA) wires is presented. The thermo-mechanical behaviors of SMA wires were experimentally measured. Hybrid composite structures were established by attaching SMA actuators on the surfaces of graphite/epoxy composite beams using bolt-joint connectors. SMA actuators were activated by phase transformation, which induced by temperature rising over austenite finish temperature. In this paper, electrical resistive heating was applied to the hybrid composite structures to activate the SMA actuators. For (aster and more accurate shape/deflection control of the hybrid composite structure, PID feedback controller was designed from numerical simulations and experimentally applied to the SMA actuators.

Hybrid Element Method for Dynamic Responses of Three-Dimensional Offshore Structures (복합요소법을 이용한 3-차원 해양구조물의 동적응답)

  • Lee, Tae-Gab;Park, Woo-Sun;Pyun, Chong-Kun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.2 no.3
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    • pp.152-161
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    • 1990
  • In this paper, a hybrid element method(HEM) for the evaluation of the hydrodynamic responses of arbitrary-shaped offshore structures is studied. The hydrodynamic pressure forces are assumed to be inertially dominated, and viscous effects are neglected. The mathematical formulation procedure of the hybrid element method with the analytical eigenseries solution is established systematically. The computer program based on the HEM has been developed, and applied to solving the wave diffraction and radiation problems for arbitrary shaped structures. From comparisons of the results obtained by using the other avaliable solution methods, the method for the evaluation of the hydrodynamic forces using the HEM and the computer program developed here have been proved to be valid.

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Experimental Cyclic Behavior of Precast Hybrid Beam-Column Connections with Welded Components

  • Girgin, Sadik Can;Misir, Ibrahim Serkan;Kahraman, Serap
    • International Journal of Concrete Structures and Materials
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    • v.11 no.2
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    • pp.229-245
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    • 2017
  • Post-earthquake observations revealed that seismic performance of beam-column connections in precast concrete structures affect the overall response extensively. Seismic design of precast reinforced concrete structures requires improved beam-column connections to transfer reversed load effects between structural elements. In Turkey, hybrid beam-column connections with welded components have been applied extensively in precast concrete industry for decades. Beam bottom longitudinal rebars are welded to beam end plates while top longitudinal rebars are placed to designated gaps in joint panels before casting of topping concrete in this type of connections. The paper presents the major findings of an experimental test programme including one monolithic and five precast hybrid half scale specimens representing interior beam-column connections of a moment frame of high ductility level. The required welding area between beam bottom longitudinal rebars and beam-end plates were calculated based on welding coefficients considered as a test parameter. It is observed that the maximum strain developed in the beam bottom flexural reinforcement plays an important role in the overall behavior of the connections. Two additional specimens which include unbonded lengths on the longitudinal rebars to reduce that strain demands were also tested. Strength, stiffness and energy dissipation characteristics of test specimens were investigated with respect to test variables. Seismic performances of test specimens were evaluated by obtaining damage indices.

Parametric study of energy dissipation mechanisms of hybrid masonry structures

  • Gao, Zhenjia;Nistor, Mihaela;Stanciulescu, Ilinca
    • Structural Engineering and Mechanics
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    • v.78 no.4
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    • pp.387-401
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    • 2021
  • This paper provides a methodology to analyze the seismic performance of different component designs in hybrid masonry structures (HMS). HMS, comprised of masonry panels, steel frames and plate connectors is a relatively new structural system with potential applications in high seismic areas. HMS dissipate earthquake energy through yielding in the steel components and damage in the masonry panels. Currently, there are no complete codes to assist with the design of the energy dissipation components of HMS and there have been no computational studies performed to aid in the understanding of the system energy dissipation mechanisms. This paper presents parametric studies based on calibrated computational models to extrapolate the test data to a wider range of connector strengths and more varied reinforcement patterns and reinforcement ratios of the masonry panels. The results of the numerical studies are used to provide a methodology to examine the effect of connector strength and masonry panel design on the energy dissipation in HMS systems. We use as test cases two story structures subjected to cyclic loading due to the availability of experimental data for these configurations. The methodology presented is however general and can be applied to arbitrary panel geometries, and column and story numbers.

Hybrid GA-ANN and PSO-ANN methods for accurate prediction of uniaxial compression capacity of CFDST columns

  • Quang-Viet Vu;Sawekchai Tangaramvong;Thu Huynh Van;George Papazafeiropoulos
    • Steel and Composite Structures
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    • v.47 no.6
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    • pp.759-779
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    • 2023
  • The paper proposes two hybrid metaheuristic optimization and artificial neural network (ANN) methods for the close prediction of the ultimate axial compressive capacity of concentrically loaded concrete filled double skin steel tube (CFDST) columns. Two metaheuristic optimization, namely genetic algorithm (GA) and particle swarm optimization (PSO), approaches enable the dynamic training architecture underlying an ANN model by optimizing the number and sizes of hidden layers as well as the weights and biases of the neurons, simultaneously. The former is termed as GA-ANN, and the latter as PSO-ANN. These techniques utilize the gradient-based optimization with Bayesian regularization that enhances the optimization process. The proposed GA-ANN and PSO-ANN methods construct the predictive ANNs from 125 available experimental datasets and present the superior performance over standard ANNs. Both the hybrid GA-ANN and PSO-ANN methods are encoded within a user-friendly graphical interface that can reliably map out the accurate ultimate axial compressive capacity of CFDST columns with various geometry and material parameters.