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Application of steel equivalent constitutive model for predicting seismic behavior of steel frame

  • Wang, Meng;Shi, Yongjiu;Wang, Yuanqing
    • Steel and Composite Structures
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    • v.19 no.5
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    • pp.1055-1075
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    • 2015
  • In order to investigate the accuracy and applicability of steel equivalent constitutive model, the calculated results were compared with typical tests of steel frames under static and dynamic loading patterns firstly. Secondly, four widely used models for time history analysis of steel frames were compared to discuss the applicability and efficiency of different methods, including shell element model, multi-scale model, equivalent constitutive model (ECM) and traditional beam element model (especially bilinear model). Four-story steel frame models of above-mentioned finite element methods were established. The structural deformation, failure modes and the computational efficiency of different models were compared. Finally, the equivalent constitutive model was applied in seismic incremental dynamic analysis of a ten-floor steel frame and compared with the cyclic hardening model without considering damage and degradation. Meanwhile, the effects of damage and degradation on the seismic performance of steel frame were discussed in depth. The analysis results showed that: damages would lead to larger deformations. Therefore, when the calculated results of steel structures subjected to rare earthquake without considering damage were close to the collapse limit, the actual story drift of structure might already exceed the limit, leading to a certain security risk. ECM could simulate the damage and degradation behaviors of steel structures more accurately, and improve the calculation accuracy of traditional beam element model with acceptable computational efficiency.

Equivalent frame model and shell element for modeling of in-plane behavior of Unreinforced Brick Masonry buildings

  • Kheirollahi, Mohammad
    • Structural Engineering and Mechanics
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    • v.46 no.2
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    • pp.213-229
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    • 2013
  • Although performance based assessment procedures are mainly developed for reinforced concrete and steel buildings, URM (Unreinforced Masonry) buildings occupy significant portion of buildings in earthquake prone areas of the world as well as in IRAN. Variability of material properties, non-engineered nature of the construction and difficulties in structural analysis of masonry walls make analysis of URM buildings challenging. Despite sophisticated finite element models satisfy the modeling requirements, extensive experimental data for definition of material behavior and high computational resources are needed. Recently, nonlinear equivalent frame models which are developed assigning lumped plastic hinges to isotropic and homogenous equivalent frame elements are used for nonlinear modeling of URM buildings. The equivalent frame models are not novel for the analysis of masonry structures, but the actual potentialities have not yet been completely studied, particularly for non-linear applications. In the present paper an effective tool for the non-linear static analysis of 2D masonry walls is presented. The work presented in this study is about performance assessment of unreinforced brick masonry buildings through nonlinear equivalent frame modeling technique. Reliability of the proposed models is tested with a reversed cyclic experiment conducted on a full scale, two-story URM building at the University of Pavia. The pushover curves were found to provide good agreement with the experimental backbone curves. Furthermore, the results of analysis show that EFM (Equivalent Frame Model) with Dolce RO (rigid offset zone) and shell element have good agreement with finite element software and experimental results.

Modified Equivalent Frame Models for Flat Plate slabs Under Lateral Load (수평하중을 받는 플랫 플레이트 슬래브 해석을 위한 수정된 등가골조모델)

  • Park Young Mi;Cho Kyung Hyun;Han Sang Whan;Lee Li Hyung
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.272-275
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    • 2004
  • This study is to propose a modified equivalent frame method under lateral loading. ACI 318-02 allows the equivalent frame method to conduct slab analysis subjected to lateral loads. However, current method can not predict the behavior of the slabs particularly under lateral loading because the equivalent frame method in the ACI 318 has been developed against gravity loads. This study provides more precise model for the analysis of the flat plate slabs under lateral loading. The model reflect the force transfer mechanism of slabs, column and torsional member more accurately than the existing model. The accuracy of this model is verified by compared with finite element method analysis results.

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A Study on the Development of Aluminum Seat Frame for Commercial Bus (상용 버스용 알루미늄 시트 프레임의 개발에 관한 연구)

  • 우호광;이상복;김상범;김헌영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.3
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    • pp.91-100
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    • 2004
  • This study presents the development of a new aluminum seat frame for the commercial bus. Back moment and seat belt anchorage analysis of the conventional steel seat frame was conducted as a base model. Effective aluminum section dimensions for aluminum pipe were calculated from equivalent stiffness and equivalent weight study. Back moment and seat belt anchorage strength with the developed aluminum seat frame were compared to those of the base model. Additionally, to pass the fatigue test, shape modification of side frame assembly was conducted. From this study we could reduce the weight of seat frame more than 5 kg. And the current analysis model and procedure can provide useful informations in designing a new commercial car seat and can reduce the overall design cost and time.

A Modified Equivalent Frame Model for Plat Plate Slabs Under Lateral Loads (수평하중을 받는 플랫 플레이트 슬래브 해석을 위한 수정된 등가골조모델)

  • Han Sang-Whan;Park Young-Mi
    • Journal of the Korea Concrete Institute
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    • v.17 no.3
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    • pp.419-426
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    • 2005
  • This study is to propose a modified equivalent frame model for flat plate slabs under lateral loads. ACI 318 (2002) allows equivalent frame methods to conduct two-way slab system analysis subjected to gravity loads as well as lateral loads. Since the equivalent frame method in the ACI 318 (2002) has been developed base on the behavior of two-way system for gravity loads, and nay not predict the behavior of flat plate slabs under lateral loads with good precision. This study develops a modified equivalent frame model which can give more precise answer for flat plate slabs under lateral loads. This model reflects the actual force transfer mechanism among the components of flat plate slab system, which are slabs, columns and torsional members, more accurately under lateral loads than existing equivalent frame models. The accuracy of this model is verified by comparing the analysis results using the proposed model with the results of finite element analysis. The analysis results of other existing models are included in the comparison. For this purpose, 2 story building having 3 spans in both directions is considered. Analytical results show that the modified equivalent frame model produces comparable drift and slab internal moments with those obtained from finite element analysis.

Analysis of the Tolerance Effects of Main Design Parameters on the Vibration Characteristics of a Vehicle Sub-frame (차량 서브프레임의 진동특성에 미치는 주요 설계변수 공차의 영향 분석)

  • Kim, Bum-Suk;Kim, Bong-Soo;Yoo, Hong-Hee
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.5
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    • pp.100-105
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    • 2008
  • In the design process of an automobile part, several analysis methods are usually utilized to evaluate the performance of the part. However, most automobile design engineers do not directly utilize CAE (Computer Aided Engineering) tools since specific skills are required to obtain practical results. Moreover, CAE requires a huge amount of computation time and cost. In order to resolve these problems, a new design approach named First Order Analysis (FOA) technique has been proposed. In this paper, the FOA technique is employed to design a vehicle sub-frame. An equivalent model of the vehicle sub-frame which only consists of beam elements is proposed and the modal properties obtained with the model are compared to those obtained with a full scale finite element model. The effect of some parameter tolerances on the modal characteristics of the vehicle sub-frame is investigated by employing the FOA equivalent model.

Masonry infilled frame structures: state-of-the-art review of numerical modelling

  • Nicola, Tarque;Leandro, Candido;Guido, Camata;Enrico, Spacone
    • Earthquakes and Structures
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    • v.8 no.1
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    • pp.225-251
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    • 2015
  • This paper presents a state-of-the-art review of the nonlinear modelling techniques available today for describing the structural behaviour of masonry infills and their interaction with frame structures subjected to in-plane loads. Following brief overviews on the behaviour of masonry-infilled frames and on the results of salient experimental tests, three modelling approaches are discussed in more detail: the micro, the meso and the macro approaches. The first model considers each of the infilled frame elements as separate: brick units, mortar, concrete and steel reinforcement; while the second approach treats the masonry infill as a continuum. The paper focuses on the third approach, which combines frame elements for the beams and columns with one or more equivalent struts for the infill panel. Due to its relative simplicity and computational speed, the macro model technique is more widely used today, though not all proposed models capture the main effects of the frame-infill interaction.

A Modified Equivalent Frame Model for Flat Plate Slabs Under Combined Lateral and Gravity Loads (조합하중시의 플랫 플레이트 슬래브 시스템에 대한 수정된 등가골조 모델)

  • Oh, Seung-Yong;Park, Young-Mi;Han, Sang-Whan
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.369-372
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    • 2006
  • Flat plate slab systems have been commonly used as a gravity force resisting systems, which should be constructed with lateral force resisting systems such as shear walls and moment resisting frame. ACI 318(2005) allows the Direct design method, the equivalent frame method (ACI-EFM) under gravity loads and the finite-element models, effective beam width models and equivalent frame models under lateral loads. ACI-EFM can be used for gravity loads as well as lateral loads analysis. But the method may not predict the behavior of flat plate slabs under lateral loads. Thus Previous study developed a Modified equivalent frame method(Modified-EFM) which could give more precise answer for flat plate slab under lateral loads. This study is to verified the accuracy of a Modified-EFM under combined lateral and gravity loads. The accuracy of this model is verified by comparing the results using the Modified-EFM with the results of finite element analysis. For this purpose, 7 story building is considered. The analysis results of other existing models are included. The analysis results show that Modified-EFM produces comparable drift and slab internal moments with those obtained from finite element analysis.

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A Comparison Study of Equivalent Strut Models for Seismic Performance Evaluation of Masonry-Infilled Frame (조적채움벽 골조의 내진성능평가를 위한 등가 스트럿 모델의 비교연구)

  • Yu, EunJong;Kim, MinJae;Jung, DaeGye
    • Journal of the Earthquake Engineering Society of Korea
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    • v.18 no.2
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    • pp.79-87
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    • 2014
  • Masonry-infilled walls have been used in reinforced concrete(RC) frame structures as interior and exterior partition walls. Since these walls are considered as nonstructural elements, they were only considered as additional mass. However, infill walls tend to interact with the structure's overall strength, rigidity, and energy dissipation. Infill walls have been analyzed by finite element method or transposed as equivalent strut model. The equivalent strut model is a typical method to evaluate masonry-infilled structure to avoid the burden of complex finite element model. This study compares different strut models to identify their properties and applicability with regard to the characteristics of the structure and various material models.

Structural Durability Analysis Related to Shape and Direction of Bicycle Frames (자전거 프레임의 형상과 방향에 따른 구조적 내구성 해석)

  • Cho, Jaeung;Han, Moonsik
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.22 no.6
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    • pp.969-975
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    • 2013
  • While accelerating, bicycle frames are subject to torsion forces and deformation. In this study, bicycle frame durability was evaluated by using structural, fatigue, and vibration experiments. Three types of models were designed by changing the frame configurations according to the shape and direction of a bicycle frame design. Because maximum equivalent stress was greatest at the saddle and at connected parts in Models 1, 2, and 3, these frame sections were most vulnerable to failure. Model 2 was the least safe, due to the increased total deformation and equivalent stresses in the top tube horizontal to the ground. Based on vibration and fatigue analysis results, Model 2 was also determined to be the least safe frame, because the head tube was placed slightly higher above the seat tube and inclined to $10^{\circ}$. These study results can be utilized in the design of bicycle frames by investigating prevention and durability against damage.