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  • Title/Summary/Keyword: Structural Flexibility

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Cost-effective structural health monitoring of FRPC parts for automotive applications

  • Mitschang, P.;Molnar, P.;Ogale, A.;Ishii, M.
    • Advanced Composite Materials
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    • v.16 no.2
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    • pp.135-149
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    • 2007
  • In the automobile industry, structural health monitoring of fiber reinforced polymer composite parts is a widespread need for maintenance before breakdown of the functional elements or a complete vehicle. High performance sensors are generally used in many of the structural health monitoring operations. Within this study, a carbon fiber sewing thread has been used as a low cost laminate failure sensing element. The experimentation plan was set up according to the electrical conductance and flexibility of carbon fiber threads, advantages of preforming operations, and sewing mechanisms. The influence of the single thread damages by changing the electrical resistance and monitoring the impact location by using carbon thread sensors has been performed. Innovative utilization of relatively cost-effective carbon threads for monitoring the delamination of metallic inserts from the basic composite laminate structure is a highlighting feature of this study.

Structural joint modeling and identification: numerical and experimental investigation

  • Ingole, Sanjay B.;Chatterjee, Animesh
    • Structural Engineering and Mechanics
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    • v.53 no.2
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    • pp.373-392
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    • 2015
  • In the present work, structural joints have been modeled as a pair of translational and rotational springs and frequency equation of the overall system has been developed using sub-structure synthesis. It is shown that using first few natural frequencies of the system, one can obtain a set of over-determined system of equations involving the unknown stiffness parameters. Method of multi-linear regression is then applied to obtain the best estimate of the unknown stiffness parameters. The estimation procedure has been developed first for a two parameter joint model and then for a three parameter model, in which cross coupling terms are also included. Two cases of structural connections have been considered, first with a cantilever beam with support flexibility and then a pair of beams connected through lap joint. The validity of the proposed method is demonstrated through numerical simulation and by experimentation.

Seismic performance evaluation of RC bearing wall structures

  • Rashedi, Seyed Hadi;Rahai, Alireza;Tehrani, Payam
    • Computers and Concrete
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    • v.30 no.2
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    • pp.113-126
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    • 2022
  • Reinforced concrete bearing walls (RCBWs) are one of the most applicable structural systems. Therefore, vulnerability analysis and rehabilitation of the RCBW system are of great importance. In the present study, in order to the more precise investigation of the performance of this structural resistant system, pushover and nonlinear time history analyses based on several assumptions drawing upon experimental research were performed on several models with different stories. To validate the nonlinear analysis method, the analytical and experimental results are compared. Vulnerability evaluation was carried out on two seismic hazard levels and three performance levels. Eventually, the need for seismic rehabilitation with the basic safety objective (BSO) was investigated. The obtained results showed that the studied structures satisfied the BSO of the seismic rehabilitation guidelines. Consequently, according to the results of analyses and the desired performance, this structural system, despite its high structural weight and rigid connections and low flexibility, has integrated performance, and it can be a good option for earthquake-resistant constructions.

Cable sag-span ratio effect on the behavior of saddle membrane roofs under wind load

  • Hesham Zieneldin;Mohammed Heweity;Mohammed Abdelnabi;Ehab Hendy
    • Wind and Structures
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    • v.36 no.3
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    • pp.149-160
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    • 2023
  • Lightness and flexibility of membrane roofs make them very sensitive to any external load. One of the most important parameters that controls their behavior, especially under wind load is the sag/span ratio of edge cables. Based on the value of the pretension force in the edge cables and the horizontal projection of the actual area covered by the membrane, an optimized design range of cable sag/span ratios has been determined through carrying on several membrane form-finding analyses. Fully coupled fluid structure dynamic analyses of these membrane roofs are performed under wind load with several conditions using the CFD method. Through investigating the numerical results of these analyses, the behavior of membrane roofs with cables sag/span ratios selected from the previously determined optimized design range has been evaluated.

Effects of the Flexibility on the Structural Responses of a Tension Leg Platform (인장계류식 해양구조물의 구조응답에 미치는 굽힘강성의 영향)

  • Lee, Chang-Ho;Lee, Soo-Lyong
    • Journal of Ocean Engineering and Technology
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    • v.21 no.4
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    • pp.38-44
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    • 2007
  • The structural response characteristics of Tension leg platforms(TLPs) in waves are examined for presenting the basic data for structural design of TLPs. The numerical approach is based on a combination of the three dimensional source distribution method and the structural response analysis method, in which the superstructure of TLP is assumed to be flexible instead of rigid. Hydrodynamic and hydrostatic forces on the submerged surface of a TLP have been accurately calculated by excluding the assumption of the slender body theory. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in structural analysis. The mooring forces are estimated as the sum of pretension of tendons and variational tension due to longitudinal displacements. Stiffness matrices of elastic beam elements connecting nodes are formulated by ordinary method of three dimensional frame analysis. The equation of motion about the whole structure is obtained by the sum of forces and moments acting on each nodes.

Lateral load effects on tall shear wall structures of different height

  • Carpinteri, Alberto;Corrado, Mauro;Lacidogna, Giuseppe;Cammarano, Sandro
    • Structural Engineering and Mechanics
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    • v.41 no.3
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    • pp.313-337
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    • 2012
  • A three-dimensional formulation is proposed to analyze the lateral loading distribution of external actions in high-rise buildings. The method is extended to encompass any combination of bracings, including bracings with open thin-walled cross-sections, which are analyzed in the framework of Timoshenko-Vlasov's theory of sectorial areas. More in detail, the proposed unified approach is a tool for the preliminary stages of structural design. It considers infinitely rigid floors in their own planes, and allows to better understand stress and strain distributions in the different bearing elements if compared to a finite element analysis. Numerical examples, describing the structural response of tall buildings characterized by bracings with different cross-section and height, show the effectiveness and flexibility of the proposed method. The accuracy of the results is investigated by a comparison with finite element solutions, in which the bracings are modelled as three-dimensional structures by means of shell elements.

A simplified method for evaluation of shear lag stress in box T-joints considering effect of column flange flexibility

  • Doung, Piseth;Sasakia, Eiichi
    • Structural Engineering and Mechanics
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    • v.73 no.2
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    • pp.167-179
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    • 2020
  • This study provides a simplified method for the evaluation of shear lag stress in rectangular box T-joints. The occurrence of shear lag phenomenon in the box T-joint generates stress concentration localized at both web-flange junctions of the beam, which leads to cracking or failure in the weld region of the joint. To prevent such critical circumstance, peak stress at the weld region is required to be checked during a preliminary design stage. In this paper, the shear lag stresses in the T-joints were evaluated using least-work solution in which the longitudinal displacements of the beam flange and web were presumed. The evaluation process considered particularly the effect of column flange flexibility, which was represented by an axial spring model, on the shear lag stress distribution. A simplified method for stress evaluation was provided to avoid solving complex mathematical problems using a stress modification factor βs from a parametric study. The results showed that the proposed method was valid for predicting the shear lag stress in the box T-joints manually, as well compared with finite element results. The results are further summarized, discussed, and clarified that more flexible column flange caused higher stress concentration.

Trend Changes of Spatial Configuration in Housing Units of Korean Apartments in the 2000s (2000년대 한국 아파트 단위세대의 공간구성 동향 변화)

  • Park, Joon Young;Jeong, Sang Kyu;Cheong, So Yi;Park, Woo Jang
    • KIEAE Journal
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    • v.12 no.1
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    • pp.21-27
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    • 2012
  • This study aims at finding the trend changes of spatial configuration in housing units of Korean apartments in the 2000s. Among the housing units in the apartments built by large construction companies, we have selected ones with small and regular sizes, 59m2 and 84m2 respectively, and investigated the number of bays, the location of wet zone and the spatial flexibility in the housing units selected for analysis. In conclusion, the number of bays in the housing unit has gradually increased, after allowing for the structural change of the balcony in the legal. It is estimated that the trend has came from the intent to increase the numbers of the externally exposed surfaces of the balcony, ensure a good view, lighting, ventilation and spatial flexibility. The location of wet zone, water-needed space such as a bathroom or a kitchen, has changed in the direction to facilitate the expansion and modification of space. Variable range of space has gradually expanded by using the balcony and wet zone as much as possible. In order to configure more effectively spaces in housing environments, the future study should be implemented to develop tools for realizing sustainable housing environment at the levels of not only the housing unit. but also the entire building, housing site, and city.

Compression of hollow-circular fiber-reinforced rubber bearings

  • Pinarbasi, Seval;Okay, Fuad
    • Structural Engineering and Mechanics
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    • v.38 no.3
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    • pp.361-384
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    • 2011
  • Earlier studies on hollow-circular rubber bearings, all of which are conducted for steel-reinforced bearings, indicate that the hole presence not only decreases the compression modulus of the bearing but also increases the maximum shear strain developing in the bearing due to compression, both of which are basic design parameters also for fiber-reinforced rubber bearings. This paper presents analytical solutions to the compression problem of hollow-circular fiber-reinforced rubber bearings. The problem is handled using the most-recent formulation of the "pressure method". The analytical solutions are, then, used to investigate the effects of reinforcement flexibility and hole presence on bearing's compression modulus and maximum shear strain in the bearing in view of four key parameters: (i) reinforcement extensibility, (ii) hole size, (iii) bearing's shape factor and (iv) rubber compressibility. It is shown that the compression stiffness of a hollow-circular fiber-reinforced bearing may decrease considerably as reinforcement flexibility and/or hole size increases particularly if the shape factor of the bearing is high and rubber compressibility is not negligible. Numerical studies also show that the existence of even a very small hole can increase the maximum shear strain in the bearing significantly, which has to be considered in the design of such annular bearings.

Second-order analysis of planar steel frames considering the effect of spread of plasticity

  • Leu, Liang-Jenq;Tsou, Ching-Huei
    • Structural Engineering and Mechanics
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    • v.11 no.4
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    • pp.423-442
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    • 2001
  • This paper presents a method of elastic-plastic analysis for planar steel frames that provides the accuracy of distributed plasticity methods with the computational efficiency that is greater than that of distributed plasticity methods but less than that of plastic-hinge based methods. This method accounts for the effect of spread of plasticity accurately without discretization through the cross-section of a beam-column element, which is achieved by the following procedures. First, nonlinear equations describing the relationships between generalized stresses and strains of the cross-section are derived analytically. Next, nonlinear force-deformation relationships for the beam-column element are obtained through lengthwise integration of the generalized strains. Elastic-plastic flexibility coefficients are then calculated by differentiating the above element force-deformation relationships. Finally, an elastic-plastic stiffness matrix is obtained by making use of the flexibility-stiffness transformation. Adding the conventional geometric stiffness matrix to the elastic-plastic stiffness matrix results in the tangent stiffness matrix, which can readily be used to evaluate the load carrying capacity of steel frames following standard nonlinear analysis procedures. The accuracy of the proposed method is verified by several examples that are sensitive to the effect of spread of plasticity.