• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.73-93
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• 2012

With an active structural involvement in spiral case structure (SCS) that is always the design and research focus of hydroelectric power plant (HPP), the compressible membrane sandwiched between steel spiral case and surrounding reinforced concrete was often assumed to be linear elastic material in conventional design analysis of SCS. Unfortunately considerable previous studies have proved that the foam material serving as membrane exhibits essentially nonlinear mechanical behavior. In order to clarify the effect of membrane (foam) material's nonlinear stress-strain behavior on SCS, this work performed a case study on SCS with a compressible membrane using the ABAQUS code after a sound calibration of the employed constitutive model describing foam material. In view of the successful capture of fitted stress-strain curve of test by the FEM program, we recommend an application and dissemination of the simulation technique employed in this work for membrane material description to structural designers of SCS. Even more important, the case study argues that taking into account the nonlinear stress-strain response of membrane material in loading process is definitely essential. However, we hold it unnecessary to consider the membrane material's hysteresis and additionally, employment of nonlinear elastic model for membrane material description is adequate to the structural design of SCS. Understanding and accepting these concepts will help to analyze and predict the structural performance of SCS more accurately in design effort.

• 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.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.189-197
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• 2018

A sprayable waterproofing membrane which has relatively high adhesive property onto concrete enables faster construction with better waterproof performance compared with a conventional sheet membrane. However, the sprayable waterproofing membrane is a recently developed material and its performance and behavior with structures are not sufficiently reported. Therefore, in this study, the shear behavior of sprayable waterproofing membrane was numerically analyzed using the results of previous studies of composite shotcrete with sprayable waterproofing membrane. From the previous study, shear behavior of shotcrete with sprayable waterproofing membrane was different from shotcrete case and there was a limitation to express the behavior of the interface in general shear strength method. Therefore, in this study, the direct shear test was numerically simulated using two contact models, and then the best suitable method to express the shear behavior of the sprayable waterproofing membrane was suggested.

• Membrane and Water Treatment
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• v.6 no.5
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• pp.393-409
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• 2015

Zinc and lead pollution are public environmental issues that have attracted lots of attention for a long time. Landfill leachate contains heavy metals, such as Zn(II) and Pb(II), which are usually related to the pollution of groundwater, especially in developing countries. Bentonite has been proven to be effective in enhancing the membrane property of clay, by which landfill liners can have better barrier performance towards the migration of contaminants. In this study, 5% sodium bentonite amended with locally available Fukakusa clay was utilized to evaluate the membrane behavior towards the heavy metals zinc and lead. The chemico-osmotic efficiency coefficient, ${\omega}$, was obtained through Zn(II) and Pb(II) solutions with different concentrations of 0.5, 1, 5, 10, and 50 mM. According to the results, ${\omega}$ continually decreased as the Zn(II) and Pb(II) concentrations increased, which is consistent with the Gouy-Chapman theory. Compared to normal inorganic ions, the membrane behavior towards heavy metal ions was lower. The migration of heavy metal ions was not observed based on experimental results, which can be attributed to the adsorption or ion exchange reaction. The mechanisms of the membrane performance change were discussed with the assistance of XRD patterns, free swelling results, XRF results, and SEM images.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.77-81
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• 2004

The massive structures are not free to move with vibration, differential settlement, thermal stresses because, construction and expansion joint, crack etc., can be large enough to cause leakage as deformation of waterproofing. It has been depended on the test method of tensile/tear strength which is waterproofing performance as behavior of concrete structure crack. However, not to practically confirm the creep applied to concrete surface, even waterproofing membrane have more performance than definite strength and elasticity. Therefore, in this study will focus on the test method to consider a resistance performance about loose adhesion and deformation of waterproofing and behavior of concrete structure as construction/expansion joint, crack. Performance test method on the influence as behavior of concrete structure crack is to choose waterproofing materials and construction method which possible to confront with behavior of 50mm crack in the atmosphere and low temperature. Examine the deformation of waterproofing membrane and loose adhesion which can occur to structure in general job site, suggest standard testing method to analyze correlation waterproofing membrane and structure with 5-types of materials used in this study, such as Adhesion membrane and sheet complex, sheet and urethane complex, self-adhesive sheet, spray poly-urea, spray membrane of rubberized Asphalt.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.1-7
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• 2003

In the study, aeroelastic behaviors and aerodynamic performances of flexible airfoil in low Reynolds number environment are evaluated. To facilitate the present study, flexible airfoil in modeled through attaching massless membrane in portion of the upper CLARK-Y airfoil surface, which is often proposed low Reynolds number airfoil. The behavior of membrane in governed by aerodynamic forces and membrane equilibrium equation. Nondimensional parameter deducted by nondimensionalizing the membrane equilibrium equation, which represents the interaction between fluid and membrane has a great influence on membrane aeroelastic behavior. Changing the starting point of the membrane is conducted on aerodynamic performances. As a result, the value of nondimensional parameter should almost linearly increase according to moving the starting point of the membrane surface toward the trailing edge.

• Fibers and Polymers
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• v.7 no.2
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• pp.123-128
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• 2006

The present study aims at characterizing and modeling the anisotropic creep behavior of coated textile membrane, a class of flexible textile composites that are used for moderate span enclosures (roofs and air-halls). The objective is to develop a creep model for predicting the lifetime of coated textile membrane. Uniaxial creep tests were conducted on three off-axis coupon specimens to obtain the directional creep compliance. A potential with three parameters is shown to be adequate for modeling the anisotropic creep behavior of coated textile membrane. Furthermore, a possibility of predicting the creep deformation of coated textile membrane in a multi-axial stress state is discussed using the three-parameter potential.

• Proceedings of the Membrane Society of Korea Conference
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• 2001.11a
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• pp.93-95
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• 2001

• Proceedings of the Membrane Society of Korea Conference
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• 2001.11a
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• pp.42-45
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• 2001

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.91-94
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• 2003

In this work, the physicochemical properties for permeant molecules and polyion complex membrane prepared by complexation between SA and chitosan were determined by using molecular modeling methods, and the permeation behaviors of water and alcohol molecules through the PIC membrane have been investigated. In the case of penetrant molecule, the experimental results showed that the prepared membrane was excellent pervaporation performance result in most solution, and the selectivity and permeability of the membrane were dependent on the molecular size, the polarity and the hydrophilic surface of permeant organics. However, the separation behavior of methanol aqueous solution exhibited other permeation tendency with other feed solutions and contradictory result. That is, the membrane were preferentially permeable to methanol over water despite water molecule has stronger polarity and small molecular size than methanol molecule. In this study, the results were discussed from the viewpoint of chemical and physical properties between permeant molecules and membrane in the diffusion state.