Some standards for the design of concrete structures (e.g. EC2 and the original ČSN 73 1201-86) allow a structure to be designed by several methods. This contribution documents the fact that even if a structure does not comply with the partial reliability factor method, according to EC2, it can satisfy the conditions during the application of the fully probabilistic approach when using the same standard. From an example of the reliability of a prestressed spun concrete pole designed by the partial factor method and fully probabilistic approach according to the Eurocode it is evident that an expert should apply a more precise (though unfortunately more complicated) method in the limiting cases. The Monte Carlo method, modified by the Latin Hypercube Sampling (LHS) method, has been used for the calculation of reliability. Ultimate and serviceability limit states were checked for the partial factor method and fully probabilistic design. As a result of fully probabilistic design it is possible to obtain a more efficient design for a structure.Keywords: probabilistic design, partial reliability factor, concrete structures design.Algúnos estándares para el diseño de estructuras de hormigón (p. ej. EC2 y la original ČSN 73 1201-86) permiten que las estructuras sean diseñadas utilizando diferentes métodos. Esta contribución trata casos en los cuales una estructura dada que incluso no obedece el método de índice de confiabilidad parcial, de acuerdo a EC2, puede satisfacer las condiciones requeridas durante la aplicación del método probabilístico cuando se usa el mismo estándar. Tomado de una muestra de la confiabilidad de un hormigón pretensado hilado diseňado con la ayuda del método de índice parcial y por el método probabilistico de acuerdo al código Euro (Eurocode) es evidente que un experto debe aplicar un método más preciso (pero desafortunadamente más complicado) en los casos limitantes. El método Monte Carlo modificado por el método (LHS) Latin Hybercube Sampling ha sido utilizado para efectuar el cálculo de confiabilidad. Los límites extremos y de utilidad fueron comprobados para el método de índice parcial y diseño probabilístico completo. Como resultado del método de diseño probabilístico es posible obtener un diseño más eficiente para una estructura.Palavras-chave: diseño probabilístico, índice de confiabilidad parcial, diseño de estructuras de hormigón. Technology, Faculty of Civil Engineering, zlamal.m@fce.vutbr.cz, Veveří 95, 602 00 Brno, Czech Republic Received: 26 Nov 2010 • Accepted: 27 Mar 2011 • Available Online: 10 Jun 2011 Abstract Resumo Fully probabilistic design -the way for optimising of concrete structures
In cases when two concrete parts are cast against in different times are not connected by dowels, main contributors to the resistance are cohesion and friction. Shear resistance of the interface is highly dependent on surface treatment and its roughness. In this paper, besides the review of available methods of surface roughness determination, the optical profilometry will be introduced and described. Optical profilometry represents non-contact and non-destructive method for characterizing surface topography. Furthermore, results obtained by abovementioned method will be compared with Sand Patch Test, in order to determine its usability and limitations.
New type of fiber reinforced polymer (FRP) reinforcement has been developed in previous years at Brno University of Technology, which can be used for reinforcing, strengthening and prestressing of concrete structures. The main advantage of FRP reinforcement is resistibility against aggressive environment and thus the possibility to use thinner concrete cover. High durability and resistibility are demanded from modern constructions. Some of the influences cover the effects of fire exposure or high temperature in general. Hence the next part of the research is focused on resistibility of FRP reinforced structures under effects of fire. The paper deals with experiments oriented to observing the behaviour of prestressed and non-prestressed FRPRC panels subjected to fire effects as well as behaviour of FRP reinforcement itself. Results of experiments proved resistibility of FRP reinforced panels to fire effects. They also demonstrate the importance of understanding the behaviour of composite reinforcing bars alone and their behaviour along the anchoring zone in concrete members exposed to fire. A sufficient anchorage length (enabling the transfer of load from the reinforcement into the concrete) turned out to be a key feature enabling a structure to withstand over much longer time periods and even under surprisingly high temperatures.
The primary aim of this article is to present design approaches for calculating the additional strengthening of masonry arches with the use of the Strut-and-Tie model and applicable standards and their comparison to the experiments. Experiments have proven the functionality of the described method of strengthening by additional inserted non-prestressed reinforcement from the face of the vault. The presented method is one of the methods of maintaining historical vaulted masonry structures, and is also used to improve the behaviour of newly designed masonry structures. This method of strengthening has its advantages, especially in the minimization of alterations to the structure and its simplicity of application. To compare the results and verify the vaults behaviour, experiments were performed with using a metallic helical reinforcement and non-metallic composite glass reinforcement. These experiments have demonstrated the significant influence of additional reinforcement on the carrying capacity of masonry vaults. The growth of bearing capacity was more than eight-fold. From a comparison of design approaches to experiments is evident that approaches to the design of additionally strengthened masonry based on valid standards are possible. The comparison of results moreover demonstrates the possibility of using approaches based on the Strut-and-Tie model.
The main aim of this study was to assess the suitability of different existing test setups for the mechanical characterization of a dimpled interface obtained by casting concrete against dimpled high-density polyethylene (HDPE) membrane. Even though this type of interface roughening is widely used, especially for monolithic connections between precast elements, to the best of the authors' knowledge there is no research providing any data regarding its roughness parameters, tension, and shear strength, nor its failure modes. To this end, a two-fold objective was established for this research: (a) to identify and analyze, from a technical standpoint, the available test configurations for characterizing the mechanical performance of interfaces, and (b) to perform an extensive experimental program devoted to characterizing the mechanical performance of a dimpled HDPE membrane-cast concrete interface. The suitability of each test for reproducing the expected stress state and the actual resistance mechanism was analyzed. Moreover, a comparison between tension and shear tests, including its main advantages and disadvantaged are also presented.
Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. One of elements, the content of which keeps rising in cement is zinc. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO)3 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05, 0.1, 0.5 a 1% of cement weight. Final products were next analyzed using X-Ray Diffraction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.