Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

This article studies the effect produced by the natural aging process in the chromatic variation on the porous face ceramic treated with water repellents, theoretically colourless, and selected according to their chemical composition. The pottery is waterproofed with each product, leaving it to age in a natural environment for twelve months, and quantifying in each month the histogram values (RGB colour space) and analysing the chromatic variation produced. In the aging process there is a general trend for all products to the loss of red and the gaining of blue, modifying its hue to tonalities which are called "cold", there is a linear relationship in each of the months of the tested materials between the initial colour and the waterproofed ceramic with each of the applied products, being possible the prediction of the final colour to be acquired in each month, depending on the applied waterproofing product.

Current architecture is characterized by specifying new typologies but not experienced until now in the engineering and architecture disciplines. Architectural free forms with non-euclidean geometries are being developed, which answer to logical analysis and parametric design, and which are tending to the mimesis of behaviour with the nature. Innovative research is developing advanced constructions of complex geometries and free forms by architects like Yushang Zhang, Rajiv Sewtahal, Riemer Postma and Qianqian Cai, Kahn, grupo Matsys, Acadia, AKT, Adler, Karan y Taylor, Emmanuel Ruffo… This paper addresses the analytical study of the set of technical solutions to the design of architectures based on geometric nature structures that will be applied to the building construction. Manufacturing and editing conditions of complex forms will characterize the innovative production systems of contemporary architecture. This study provides a strong documental foundation for research on the significance of new structural and constructive systems in the production of the current architecture.

The major employer in Turkish construction sector is the public and the selection of contractor within the public sector is implemented in accordance with the regulations. Sound utilization of public resources in developing countries with certain development plans is very important; also the establishment of transparency and competition in public procurement increases saving and encourages the correct usage of tax revenues. Within this context, keeping the quality while increasing the level of competition and having successful public investments will be possible by selecting the most ideal contractor. The key for success in public investments on construction projects is to provide the minimum project cost with the ability to reach at the required quality level within the determined period; and therefore some criteria other than the amount of bid should be determined for construction tenders and the evaluation should be one within the scope of such criteria in order to select the contractor. A fuzzy logic methodology is used within the scope of this study, in which the criteria except the price are evaluated with the help of a model and the verbal terms are modeled.

Through a very simple washing process with water, the unburned carbon is separated and removed from the fly ash. In this work, mixtures of mortar with 30% Portland cement replacement are made by different additions: integral fly ash (obtained from thermoelectric), washed fly ash (removing unburned carbon by washing), unburned carbon and limestone filler (limestone rock dust). To determine better the pozzolanic contribution of the additions, 5% gypsum (with respect to the weight of the binder) is added to the mixtures not hardened. With these mixtures, specimens are made for tests to rupture at 7, 28 and 90 days of age, kept submerged in water and also special specimens kept in similar condition measuring length variations. It is detected that the substitution of portland cement by unburned carbon, significantly reduces the mechanical resistance at any age and does not contribute to protection against sulphate attacks. It is concluded that the unburned carbon does not possess pozzolanic properties and its withdrawal generates benefits to the fly ash in the search to improve the pozzolanic performance in concrete mixtures.

The use of artificial neural networks as a modeling tool for the physic-mechanical properties of diverse materials has experienced great advances in the last ten years, mainly due to the increased in computing capacities of computers. This technique has been used in many different fields of science and its effectiveness is sufficiently proven. Its application in the particle board industry complies with the requirements of the test regulations for the use in production control, as an alternative method to normalized one. However, in spite of providing a result with a great approximation, they do not indicate anything about the uncertainty of the result. This last point is crucial when the results have to be compared with a product standard. There are internationally accepted deterministic techniques for obtaining the uncertainty of a test result, always starting from the knowledge of the function that relates the measure with the measurement parameters. However, these techniques are not entirely adequate for the case of excessively complex functions such as an artificial neural network. In these cases, the use of stochastic simulation methods such as the Monte Carlo method is more appropriate. In this article, an artificial neural network will be developed to obtain the compressive strength of high-strength concrete to later obtain the uncertainty by a Monte Carlo simulation.

Current research work is aimed to numerically simulate the failure behavior of Fiber Reinforced Polymer (FRP) strengthened reinforced concrete beams having different FRP reinforcement ratios. Required objectives are achieved by performing a series of bending tests on RC beams carrying different FRP layout and FRP reinforcement ratio. Tested beams were numerically simulated by using a Finite Element Method based computer package. The layouts of the FRP strengthening were decided based upon the FRP reinforcement ratios ranging from fully wrapped beams to the beams having significantly lower FRP reinforcement ratios. Tests results are presented in the form of load-deflection curves for all of the beams and a comparison of different beam strengthening schemes is also presented. Failure patterns of RC beams strengthened with different layouts of externally bonded FRP sheets were also compared. Results of flexural tests on twelve beams specimens and numerical simulation have indicated that CFRP and GFRP can significantly increase the bending and shear strength of retrofitted beams. However, the use of higher FRP reinforcement ratios to get higher strength increment is not advisable as epoxy properties and concrete surface quality plays a vital role to increase flexural and shear strength.

Significantly growing construction in the earthquake vulnerable regions needs appropriate handling of seismic prone buildings. Insertion of high damping rubber bearing (HDRB) at the building base might be an attractive option for structural safety and economy. This study deals with incorporation of HDRB device in building base and focus on the change of structural behavior for its different categories. Structural responses of base isolated (BI) buildings under site- specific seismic excitation are analyzed. The superstructure of multistoried buildings is represented by a finite element (FE) model comprising multi-degree of freedom. The structural analyses involve the BI as well as fixed base (FB) buildings. The commercial finite element packages SAP 2000 has been used to determine the variation in structural responses performing static and dynamic analyses. Twenty prototype building frames are modelled considering four HDRB categories. The HDRB is found to make the buildings more flexible reducing the seismic responses. The increased natural period leads more importance of building flexibility effects and so the horizontal shift of superstructure increases. The story shear reduces significantly and eventually the reduced overturning moment indicates that the forces are highly overestimated if the bearing is not employed. The acceleration profile presents good agreement with the isolation strategy. Without bearing, story accelerations will be largely glorified. To lessen corresponding story shears and story accelerations HDRB can be chosen as per the specifications and necessities. Such HDRB isolated buildings can withstand rather high seismic tremors in a safe and efficient manner due to radical reduction of story responses and good structural flexibility.

This paper presents the modeling of an experimental investigation carried out to evaluate some mechanical and durability properties of concrete mixtures in which cement was partially replaced with Class C and Class F fly ash. A total of 39 mixtures with different mix designs were prepared. After compressive strength testing, the mixtures containing Class F and Class C fly ashes which had similar compressive strength values to control mixtures at 28 d for each series were used for sulfate resistance tests. The degree of sulfate attack was evaluated using expansion and weight loss. The test results indicated that Class C fly ash showed higher compressive strength than Class F fly ash. Moreover, the addition of fly ash significantly increased the resistance to sulfate attack when each amount of fly ash addition regardless of fly ash types was employed. In this paper, the Artificial Neural Network (ANNs) techniques were used to model the relative change in the weight and length of the concrete exposed to sulfate. The best algorithm for length changes of concrete exposed to sulfate is BFGS quasi-Newton backpropagation algorithm while the best algorithm for weight changes of concrete exposed to sulfate is the Levenberg-Marquardt backpropagation algorithm.

Currently in Chile several programs are used in order to promote sustainable construction. On this scenario was created S.D. N°. 255 of the House and Urban Development Minister of Chile which, among other objectives, seeks to thermally refurbish houses to provide greater comfort to the inhabitants of this. In practice, this thermal reconditioning has not been implemented in the Metropolitan Region due to in none of its versions funds have been allocated to it. This paper quantifies how much the social benefit would increase if the subsidy was applied in RM. For this, various representative dwellings of housing stock were modeled and was done an economic analysis that led to the conclusion that it is beneficial, at least from a social standpoint, its application.

This paper presents a framework for the "Santiago Integrated Energy Model" or SIEM. This model establishes an optimized energy balance between the photovoltaic generation potential and the electric consumption curves of a specific Urban Energy District (EUD), designed for the city of Santiago. To validate local data, a methodology has been developed in three stages: the potential prospection and the curves estimation; the data calibration; and the EUD identification. The model has been applied in an hypothetical urban area to develop a consistency test, obtaining adequate results on the balance curves of the model, considering both the potential generation and consumption (according to uses and schedules). The results reflect the relevance of applying this model to a real urban area in Santiago of Chile, to establish optimization correlations for an empirical validation.