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In-plane transversal normal stresses in the concrete face of CFRD induced by the first-dam reservoir filling

Frontiers of Structural and Civil Engineering 2018年第1期12卷 81-91页

作者： neftali sarmiento-solano Miguel P. ROMO l Institute of Engineering National University of Mexico Mexico City 0451 O Mexico

To evaluate the effects of dam height, valley narrowness and width of concrete slabs on the first-dam reservoir filling in-plane transversal normal stresses in the concrete face of CFRD＇s, 3D finite difference analyses were carried out. Behavior of rockfiU dams considered in this study was defined from the monitoring of a number of 3D sets of pressure cells and extensometers installed in three large dams in Mexico. The 3D analyses results show that high in-plane transversal compressive stresses develop within the concrete panels located in the central concrete face zone upon dam reservoir filling loading. Likewise, in-plane induced tensile transversal stresses in the zones near the abutments increase the potential of slabs cracking and damaging the waterstops in-between the vertical and perimetral joints. From the results of the 3D finite difference analyses, a simple method to estimate in-plane normal stresses in the concrete face is advanced and through comparisons with the results of a 3D case numerical study, its accuracy assessed.

关键词： concrete face CFR dams reservoir filling slab in-plane stresses

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Dynamic in-plane transversal normal stresses in the concrete face of CFRD

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 135-148页

作者： neftali sarmiento-solano Miguel P.ROMO Institute of Engineering National University of MexicoMexico City04510Mexico

Severe earthquakes can induce damages to Concrete Face Rocldill Dams (CFRDs)such as concrete cracking and joint's water stops distressing where high in-plane transversal normal stresses *** these damages rarely jeopardize the dam safety,they cause large water reservoir leakages that hinder the dam *** issue can be addressed using well know numerical methods;however,given the wide range of parameters involved,it would seem appropriate to develop a simple yet reliable procedure to get a close understanding how their interaction affects the CFRD's overall ***,once the physics of the problem is better understood one can proceed to perform a detailed design of the various components of the *** this end an easy-to-use procedure that accounts for the dam height effects,valley narrowness,valley slopes,width of concrete slabs and seismic excitation characteristics was *** procedure is the dynamic complement of a method recently developed to evaluate in-plane transversal normal stresses in the concrete face of CFRD's due to dam reservoir filling [1].Using these two procedures in a sequential manner,it is possible to define the concrete slab in-plane normal stresses induced by the reservoir filling and the action of orthogonal horizontal seismic excitations acting at the same time upstream-downstream and cross *** procedures were developed from a data base generated using nonlinear static and dynamic three-dimensional numerical analyses on the same group of CFRD'***,the results were interpreted with the Buckingham Pi theorem and various relationships were *** the above reference,the method to evaluate the concrete face in-plane transversal normal stresses caused by the first reservoir filling was *** this paper,the seismic procedure is first developed and then through an example the whole method (dam construction,reservoir filling plus seismic loading)of analysis is assessed.

关键词： CFR dams dynamic analysis in-plane normal stresses concrete face

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YbF_3/SiO_2 Fillers as Radiopacifiers in a Dental Adhesive Resin

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Nano-Micro Letters 2012年第3期4卷 189-196页

作者： neftali L.V.Carreno Thiago C.S.Oliveira Evandro Piva Fernanda B.Leal Giana S.Lima Marcelo D.Moncks Cristiane W.Raubach Fabricio A.Ogliari Technology Development Center Engineering of MaterialFederal University of Pelotas Biomaterials Development and Control Center School of DentistryFederal University of Pelotas Department of Analytical and Inorganic Chemistry IQGFederal University of Pelotas

The objective of this study was to evaluate the effect of functionalizing a dental adhesive resin with YbF_3/SiO_2 fillers for use as *** of YbF_3/SiO_2 were obtained with the high-energy mechanical milling method and characterized by both physical and chemical *** characterization,the particles were sieved and silanized prior to being incorporated into an adhesive *** stability of the particle suspension was then *** light activation,the radiopacity,degree of conversion,flexural strength and elastic modulus were *** dental adhesive resins with 10 and 15 wt% of filler provided satisfactory radiopacity,while flexural strength and elastic modulus were not *** degree of conversion was statistically lower than that of the control(p<0.05).The method used for incorporating the tested ytterbium fluoride/silicon dioxide particles at concentrations of 10 and 15 wt% was shown to be feasible for the development of a radiopaque dental adhesive system.

关键词： Radiopacifier YbF3/SiO2 Dental adhesive resin Composite

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