• Title/Summary/Keyword: Structural Flexibility

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Damage Detection in High-Rise Buildings Using Damage-Induced Rotations

  • Sung, Seung Hun;Jung, Ho Youn;Lee, Jung Hoon;Jung, Hyung Jo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.6
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    • pp.447-456
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    • 2014
  • In this paper, a new damage-detection method based on structural vibration is proposed. The essence of the proposed method is the detection of abrupt changes in rotation. Damage-induced rotation (DIR), which is determined from the modal flexibility of the structure, initially occurs only at a specific damaged location. Therefore, damage can be localized by evaluating abrupt changes in rotation. We conducted numerical simulations of two damage scenarios using a 10-story cantilever-type building model. Measurement noise was also considered in the simulation. We compared the sensitivity of the proposed method to localize damage to that of two conventional modal-flexibility-based damage-detection methods, i.e., uniform load surface (ULS) and ULS curvature. The proposed method was able to localize damage in both damage scenarios for cantilever structures, but the conventional methods could not.

Effect of local joint flexibility on the fatigue lfe assessment of jacket-type offshore platform

  • Behrouz Asgarian;Parviz Kuzehgar;Pooya Rezadoost
    • Ocean Systems Engineering
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    • v.14 no.1
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    • pp.1-16
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    • 2024
  • This paper investigates the impact of local joint flexibility (LJF) on the fatigue life of jacket-type offshore platforms. Four sample platforms with varying geometric properties are modeled and analyzed using the Opensees software. The analysis considers the LJF of tubular joints through the equivalent element and flexible link approaches, and the results are compared to rigid modeling. Initially, modal analysis is conducted to examine the influence of LJF on the frequency content of the structure. Subsequently, fatigue analysis is performed to evaluate the fatigue life of the joints. The comparison of fatigue life reveals that incorporating LJF leads to reduced fatigue damage and a significant increase in the longevity of the joints in the studied platforms. Moreover, as the platform height increases, the effect of LJF on fatigue damage becomes more pronounced. In conclusion, considering LJF in fatigue analysis provides more accurate results compared to conventional methods. Therefore, it is essential to incorporate the effects of LJF in the analysis and design of offshore jacket platforms to ensure their structural integrity and longevity.

Outrigger Systems for Structural Design of Complex-Shaped Tall Buildings

  • Moon, Kyoung Sun
    • International Journal of High-Rise Buildings
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    • v.5 no.1
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    • pp.13-20
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    • 2016
  • Today's architecture can be best understood only through the recognition of pluralism, and, as is true of other building types, multiple design directions are prevalent for tall buildings. This contemporary design trend has produced many complex-shaped tall buildings, such as twisted, tilted and tapered form towers. Among many different structural systems developed for tall buildings, the outrigger system, with its inherent structural efficiency and flexibility in façade design, is widely used for contemporary tall buildings. This paper studies structural performance of outrigger systems employed for complex-shaped tall buildings. Twisted, tilted and tapered tall buildings are designed with outrigger structures, and their structural performance is investigated. For the twisted outrigger study, the buildings are twisted up to 3 degrees per floor. In the tilted outrigger study, the angles of tilting range from 0 to 13 degrees. The impact of eccentricity is investigated for gravity as well as lateral loads in tilted towers. In the study of tapered outrigger structures, the angles of tapering range from 0 to 3 degrees. Parametric structural models are generated using appropriate computer programs for these studies, and the models are exported to structural engineering software for design and analyses.

Modelling of Structural Adhesives for Body Stiffness Analysis in Automobile (차체 강성해석을 위한 구조용 접착제 해석모델링 연구)

  • Seo, Seong-Hoon;Joo, Jae-Kap
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1410-1414
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    • 2007
  • In modern automobile body manufacturing, the structural adhesive bonding is recognized to one of new joining techniques for the purpose of light weight body and its application scope in the automobile body has been gradually magnified. Specially, the structural adhesives have the advantages of not only enhancing the design flexibility of automobile body, but also improving automobile performances such as stiffness, crashworthiness and durability. In order to evaluate the performance simulation of the automobile body applied with structural adhesives, it is necessary to develop modeling techniques in the structural adhesives in advance. This paper aims to investigate modeling methodology of structural adhesive junctions for body stiffness simulation. Two main modeling points are the element selection for adhesives and the connectivity between adhesives and adherends. Both of the 1D element used in classical modeling and the 3D element which are more accurate are considered for the adhesives, and the congruent and incongruent mesh models of the adherends are compared for connectivity modeling. By applying the several kinds of modeling methodology to the simple structures, the simulation results are compared and some modeling guidelines are obtained.

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Applications of fiber optic sensors for structural health monitoring

  • Kesavan, K.;Ravisankar, K.;Parivallal, S.;Sreeshylam, P.
    • Smart Structures and Systems
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    • v.1 no.4
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    • pp.355-368
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    • 2005
  • Large and complex structures are being built now-a-days and, they are required to be functional even under extreme loading and environmental conditions. In order to meet the safety and maintenance demands, there is a need to build sensors integrated structural system, which can sense and provide necessary information about the structural response to complex loading and environment. Sophisticated tools have been developed for the design and construction of civil engineering structures. However, very little has been accomplished in the area of monitoring and rehabilitation. The employment of appropriate sensor is therefore crucial, and efforts must be directed towards non-destructive testing techniques that remain functional throughout the life of the structure. Fiber optic sensors are emerging as a superior non-destructive tool for evaluating the health of civil engineering structures. Flexibility, small in size and corrosion resistance of optical fibers allow them to be directly embedded in concrete structures. The inherent advantages of fiber optic sensors over conventional sensors include high resolution, ability to work in difficult environment, immunity from electromagnetic interference, large band width of signal, low noise and high sensitivity. This paper brings out the potential and current status of technology of fiber optic sensors for civil engineering applications. The importance of employing fiber optic sensors for health monitoring of civil engineering structures has been highlighted. Details of laboratory studies carried out on fiber optic strain sensors to assess their suitability for civil engineering applications are also covered.

An Experimental Study on the Structural Behavior of Double-Angle Shear Connections in Steel Structures (강구조 복앵글 전단 접합부의 구조적 거동에 관한 실험적 연구)

  • Lee, Do-Hyung;Kim, Seok-Jung
    • Journal of Industrial Technology
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    • v.17
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    • pp.305-312
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    • 1997
  • Shear connections in steel structures should satisfy dual criteria of shear strength and rotational flexibility and ductility. The connection should be strong enough to transfer the shear reaction of the beam, and should have sufficient rotational flexibility and ductility to rotate easily and supply the end rotation demand of the beam. This paper is concerned with the behavior of double-angle shear connections where the parameters are numbers of high strength bolts, bolt pitch, the length of angle leg, and connection method. An experimental investigation of shear connection was conducted by testing 12 beam-to-column joint specimens. Based on experimental and analytical study, the failure modes are developed and proposed design formulas.

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An efficient partial mixed finite element model for static and free vibration analyses of FGM plates rested on two-parameter elastic foundations

  • Lezgy-Nazargah, M.;Meshkani, Z.
    • Structural Engineering and Mechanics
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    • v.66 no.5
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    • pp.665-676
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    • 2018
  • In this study, a four-node quadrilateral partial mixed plate element with low degrees of freedom (dofs) is developed for static and free vibration analysis of functionally graded material (FGM) plates rested on Winkler-Pasternak elastic foundations. The formulation of the presented finite element model is based on a parametrized mixed variational principle which is developed recently by the first author. The presented finite element model considers the effects of shear deformations and normal flexibility of the FGM plates without using any shear correction factor. It also fulfills the boundary conditions of the transverse shear and normal stresses on the top and bottom surfaces of the plate. Beside these capabilities, the number of unknown field variables of the plate is only six. The presented partial mixed finite element model has been validated through comparison with the results of the three-dimensional (3D) theory of elasticity and the results obtained from the classical and high-order plate theories available in the open literature.

Effects of Fashion Goods Promotion Strategy to CRM (Customer Relationship Management)

  • Lee, Byoung-Hwa;Shim, Hwa-Jin
    • Journal of Fashion Business
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    • v.8 no.3
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    • pp.34-48
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    • 2004
  • This study aims to determine any possible causation between identifying which major factors affect CRM(Customer Relationship Management) in terms of promotion strategies for fashion goods and classifying customers into several categories, so that it can seek reasonable strategic measures based on CRM. This study suggested a model by selecting several variables meeting its goals, and used total 672 sheets of questionnaire for final analysis. In addition, a structural equation model was analyzed As a result, it was found that pricing flexibility had more or less influential relationships with trust, satisfaction and commitment in CRM, although having a negative relationship with commitment. Salesperson's role was also significantly correlated with trust, satisfaction and commitment in CRM, and especially, there were more influential relationships with satisfaction than any other factor. Service quality had relatively high influential relationships with trust, satisfaction and commitment in CRM. Retained customers showed more or less influential relationships with trust, satisfaction and commitment, while loyal customers did so with satisfaction and commitment, except for trust.

속이 찬 실린더와 평판의 접합부에 관한 연구

  • 김윤영
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.12
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    • pp.2241-2251
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    • 1992
  • This work is concerned with the investigation of end effects of a cylinder on a structure where a circular plate is attached to a solid circular cylinder. Three-dimensional elasticity solutions are used in a cylinder whereas the classical thin plate theory is employed for a plate. The end effect of the cylinder on the flexibility and the structural response is demonstrated by several numerical examples.

A reinforced concrete frame element with shear effect

  • Valipour, Hamid R.;Foster, Stephen J.
    • Structural Engineering and Mechanics
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    • v.36 no.1
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    • pp.57-78
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    • 2010
  • A novel flexibility-based 1D element that captures the material nonlinearity and second order P-Δ effects within a reinforced concrete frame member is developed. The formulation is developed for 2D planar frames in the modified fiber element framework but can readily be extended to 3D cases. The nonlinear behavior of concrete including cracking and crushing is taken into account through a modified hypo-elastic model. A parabolic and a constant shear stress distribution are used at section level to couple the normal and tangential tractions at material level. The lack of objectivity due to softening of concrete is addressed and objectivity of the response at the material level is attained by using a technique derived from the crack band approach. Finally the efficiency and accuracy of the formulation is compared with experimental results and is demonstrated by some numerical examples.