• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.506-509
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• 2004

This paper proposes Headed bar as reinforcement of beam-column joint, and proves seismic performance and reduction of reinforcement congestion. In these case, the use of Headed bars have obvious advantages. The greatest benefit of using Headed bars is not only improved structural performance of beam-column joints, but also the ease of fabrication, construction, and placement. Three-dimensional finite element analysis model is compared with test program which was fulfilled by the proposed model with Headed bar. Also, the plastic hinge region is relocated to the center of the longitudinal beam length according to the strong column-weak beam design philosophy, so Headed bar is used as the joint reinforcement. Therefore, this paper presents results of a computer analysis of a practical solution for relocating potential beam plastic hinge regions by the placing of straight - Headed bar.

• Steel and Composite Structures
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• v.15 no.3
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• pp.299-322
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• 2013

In the case of seismic-resistant composite dual moment resisting and eccentrically braced frames, the current design practice is to avoid the disposition of shear connectors in the expected plastic zones, and consequently to consider a symmetric moment or shear plastic hinges, which occur only in the steel beam or link. Even without connectors, the real behaviour of the hinge may be different from the symmetric assumption, since the reinforced concrete slab is connected to the steel element close to the hinge locations, and also due to contact friction between the concrete slab and the steel element. The paper presents the results and conclusions of experimental tests on composite portal eccentrically braced frames and beam-to-column moment-resisting joints, carried out within the CEMSIG Research Centre of the Politehnica University of Timisoara, in order to check the validity of the assumption stated above. Reference steel and composite specimens with and without connectors in the plastic zones have been tested under monotonic and cyclic seismic type loading.

• Structural Engineering and Mechanics
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• v.4 no.1
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• pp.9-23
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• 1996

The behaviour of elasto-plastic planar arches subjected to dynamic loads in presented. The governing equations are formulated through the dynamic equations and compatibility conditions. The latter is established by applying the generalized conjugate segment analogy. Bending moments at the nodes and axial forces in the members are considered as primary variables in the elastic regime. They are supplemented by the rotations at the nodes and dislocations in the elements when plastic hinges occur. Newmark-${\beta}$ method is adopted in the time marching process. The interaction diagram of each element is treated as the yield surface for the element and the associated flow rule is enforced as plastic flow occurs. The method provides good prediction of dynamic response of elasto-plastic arches while requiring small core storage and short computer time.

• Steel and Composite Structures
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• v.30 no.3
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• pp.271-280
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• 2019

In this paper, numerical and experimental assessments have been conducted in order to investigate the capability of using CFRP for the seismic capacity improvement and relocation of plastic hinge in reinforced concrete connections. Two scaled down exterior reinforced concrete beam to column connections have been used. These two connections from a strengthened moment frame have been tested under uniformly distributed load before and after optimization. The results of experimental tests have been used to verify the accuracy of numerical modeling using computational ABAQUS software. Application of FRP plate on the web of the beam in connections to improve its capacity is of interest in this paper. Several parametric studies were carried out for CFRP reinforced samples, with different lengths and thicknesses in order to relocate the plastic hinge away from the face of the column.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.438-443
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• 1998

Softening os the name used for decreasing bending moment at advanced flexural deformation. To accommodate softening deformation in analysis, it is assumed that a hinge has finite length. The softening analysis of R/C frames relies on the primary assumption that softening occurs over a finite hinge length and that the moment-curvature relationship for any section may be closely described by a trilinear approximation. A stiffness matrix for elastic element with softening regions are derived and the stiffness matrix allows extension of the capability of an existing computer program for elastic-plastic analysis to the softening situation. The effect of softening on the collapse load of R/C frame is evaluated.

• International conference on construction engineering and project management
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• 2024.07a
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• pp.1317-1317
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• 2024

As climate change escalates extreme weather events, the structural durability of plastic greenhouses, constituting 90% of Korea's facility agriculture, emerges as a critical issue. These greenhouses are pivotal for year-round crop cultivation and high-quality agricultural production. In 2021, collapses caused around US$2 million in damages, mainly due to heavy snowfall and strong winds, accounting for 97% of incidents. The Korean Ministry of Agriculture responded by disseminating disaster-resistant standardized designs, yet more robust standards are needed. Current designs rely on elastic analysis, but plastic greenhouses display nonlinear behavior due to factors like residual stress and local buckling. Our study employs a refined plastic hinge method and finite element analysis to analyze structures, considering progressive yielding. We conducted loading tests using scale down models of plastic greenhouses in accordance with similitude laws. Based on these tests, the deformation of models under different load conditions was measured and compared with the deformation of greenhouse using our nonlinear structural analysis. This study will contribute to the development of reliable design criteria for plastic greenhouses in response to climate extremes such as heavy snowfall and typhoons. In addition, by identifying the deformation characteristics of plastic greenhouses due to loads, it can contribute to establishing usability standards for greenhouses, and reinforcement measures for vulnerable areas which are easily deformed under load can be considered.

• Earthquakes and Structures
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• v.24 no.1
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• pp.11-20
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• 2023

"Performance-based design (PBD)" is based on designing a structure with choosing a performance target under design criteria to increase the structure's resistance against earthquake effect. The plastic hinge formation is determined as one of the fundamental data in finite elements nonlinear analysis to distinguish the condition of the structure where more significant potential damage could occur. If the number of plastic hinges in the structure is increased, the total horizontal load capability of the structure is increased, also. Theoretically, when the number of plastic hinges of the plane frame structure reaches "the degree of hyperstaticity plus one", the structure will reach the capability of the largest ultimate horizontal load. As the number of plastic hinges to be formed in the structure increases towards the theoretical plastic hinge number (TPHN), the total horizontal load capability of the structure increases, proportionally. In the previous studies of the authors, the features of examining the new performance criteria were revealed and it was formulated as follows "Increase the total number of plastic hinges to be formed in the structure to the number of theoretical plastic hinges as much as possible and keep the structure below its targeted performance with related codes". With this new performance criterion, it has been shown that the total lateral load capability of the building is higher than the total lateral load capability obtained with the traditional PBD method by the FEMA 440 and FEMA 356 design guides. In this study, PBD analysis results of structures with frame carrier systems are presented in the light of the Turkey Building Earthquake Code 2019. As a result of this study, it has been shown that the load capability of the structure in the examples of structures with frame carrier system increases by using this new performance criterion presented, compared to the results of the examination with the traditional PBD method in TBEC 2019.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.201-206
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• 2001

This paper presents truss model that can be used to determine the deformation as well as strength of RC members. This model is constituted to address plastic hinge rotation at tile deformation concentrated regions under severe lateral load. The behavior of each element of truss model is evaluated on the basis of stress field analysis. The deformation is obtained by combining element deformations with joint rotation. Initial strength is calculated at the first failure of any element, and strength deterioration after failure depends on the strength reduction of this element. The proposed model will provide useful tools in seismic design of ductility-required members.

• Earthquakes and Structures
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• v.26 no.3
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• pp.175-189
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• 2024

Aiming at studying the plastic hinge (PH) evolution regularities and failure mode of rocking wall moment frame (RWMF) structure in earthquakes, the whole-working history analysis of seismic performance state of RWMF structure based on co-operation performance and PH evolution was carried out. Building upon the theoretical analysis of the elastic internal forces and deformations of RWMF structures, nonlinear finite element analysis (FEA) methods were employed to perform both Pushover analysis and seismic response time history analysis under different seismic coefficients (δ). The relationships among PH occurrence ratios (R_ph), inter-story drifts and δ were established. Based on the plotted curve of the seismic performance states, evaluation limits for the R_ph and inter-story drifts were provided for different performance states of RWMF structures. The results indicate that the R_ph of RWMF structures exhibits a nonlinear evolution trend of "fast at first, then slow" with the increasing of δ. The general pattern is characterized by the initial development of beam hinges in the middle stories, followed by the development towards the top and bottom stories until the beam hinges are fully formed. Subsequently, the development of column hinges shifts from the bottom and top stories towards the middle stories of the structure, ultimately leading to the loss of seismic lateral capacity with a failure mode of partial beam yield, demonstrating a global yielding pattern. Moreover, the limits for the R_ph and inter-story drifts effectively evaluate the five different performance states of RWMF structures.

• Journal of Ocean Engineering and Technology
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• v.12 no.1
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• pp.10-22
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• 1998

In the present work the elastic-plastic FE formulations using dynamic explicit time integration schemes are used for numerical analysis of a large auto-body panel stamping processes. For analyses of more complex cases with larger and more refined meshes, the explicit method is more time effective than implicit method, and has no convergency problem and has the robust nature of contact and friction algorithms while implicit method is widely used because of excellent accuracy and reliability. The elastic-plastic scheme is more reliable and rigorous while the rigid-plastic scheme require small computation time. In finite element simulation of auto-body panel stamping processes, the roobustness and stability of computation are important requirements since the computation time and convergency become major points of consideration besides the solution accuracy due to the complexity of geometry conditions. The performnce of the dynamic explicit algorithms are investigated by comparing the simulation results of formaing of complicate shaped autobody parts, such as a fuel tank and a rear hinge, with the experimental results. It has been shown that the proposed dynamic explicit elastic-plastic finite element method enables an effective computation for complicated auto-body panel stamping processes.