This paper proposes and validates a numerical iterative model to evaluate the thermal resistance of multilayer systems (walls) when in a dynamic state. First, the validation is performed numerically, then the second step of validation uses the temperature and heat flux values recorded during experimental tests performed in a hot box chamber. These validations involve comparing the results obtained with those expected, given the thermal properties of each material and thickness of each wall layer. The paper first presents the analytical solution for simulating heat transfer by conduction in the frequency domain, through the multilayer system. This is generated by imposing temperatures on the external surfaces, when the thermal properties of the materials are known. The model is then modified by assuming the wall is composed of a single layer with unknown thermal properties. The temperatures and heat fluxes, provided earlier by the analytical model and imposed on the external surfaces, lead to a nonlinear system that can be solved for the unknown thermal properties. It is solved by implementing an iterative approach based on the Newton-Raphson method. After the validation of the proposed model, this is used to evaluate the thermal resistance of a multilayered wall subjected to real conditions.
The paper illustrates the experimental techniques and the experimental results obtained at the Wall of Wind WoW of Florida International University (FIU), in Miami, concerning some tests on trees under wind loading. The motivation of the scientific work comes from unresolved questions that the designers of high rise buildings in Milano had to deal with in the design of the flower box containing trees up to 6-7 m high. The question was: can the tree fall down the terrace by turning inside the box or by breaking the trunk of the tree? How can be evaluated the forces due to wind? Thanks to the Real Estate Investment promoter, HINES Italia, an experimental program has been organized and implemented at a wind tunnel facility (WoW at FIU) which could allow for testing full scale trees.
The disastrous Izmit 1999 earthquake besides causing loss of life, has also produced significant damage to the engineering structures. In this study, the effect of underlying soil to the structural damage is investigated without taking into account structural effects that caused damage to structures. Critical soil data inputs is used to investigate the effect of soil conditions on damage potential of the existing buildings in the cities Kocaeli and Sakarya during 1999 earthquake. Artificial neural network method is used to determine the damage potential of the buildings. Data derived from around 259 borehole logs were used as input dataset to artificial neural network model. Predicted output is a ratio obtained from structural damage which gives an insight on the potential structural damage. Analysis showed that best success is reached with 4 layer backpropagation neural and general regression neural network. The results of this study indicate that the damage potential of the engineering structures is highly correlated to soil conditions.
Rapid urban growth in sub-Saharan Africa is generally caused by poverty and disaster. The resulting shantytowns, overcrowding, and lack of infrastructure have been widely recorded. But what happens if a remote rural village – largely untouched by colonialism – is abruptly subjected to the pressures of globalisation and prosperity? Letlhakane is the fastest growing town in Botswana, due to diamond mining. This paper focuses on Letlhakane, and aims to determine how rapid growth, material prosperity and the influx of strangers has been influencing the relationship between 1) settlement form, 2) culture and 3) the customary spatial patterns. The Tswana (the dominant indigenous population) have an uninterrupted history of settlement building in southern Africa, stretching back nearly 600 years, which produced agro-towns (reportedly as big as contemporaneous Cape Town) by the early 19th century. Letlhakane offers a rare opportunity to track the unfolding of an indigenous settlement model, from the Iron Age into the 21st century. Whereas Gaborone and Francistown, Botswana’s largest cities, were colonial creations, Letlhakane’s transformation is a postcolonial phenomenon. Letlhakane has retained an informal morphology up to now, instead of the barrack-style layout of Orapa (a company mining town only 20 kilometres away), albeit somewhat denser and less organic than a typical 19th century Tswana agricultural town, such as Shoshong. In fact, it seems as if Letlhakane is mutating from one state of informality, into another. In order to contextualise Letlhakane’s transformation, it is compared to nearby Orapa and Shoshong, by applying Kevin Lynch’s classic elements of paths, edges, districts, nodes and landmarks with a focus on geometry and land-use intensity.
Present paper presents the technical specifications of an experimental equipment able to perform an in situ diagonal compression test on a masonry specimen with displacement control. It is, therefore, capable to evaluate ductility behaviour also after the peak load. In addition, the equipment is capable to evaluate the different mechanical behaviour of a masonry specimen made of two external layers and a central core with different mechanical characteristics. The application of that equipment is described with reference to a couple of masonry specimens located in an historical building, Palazzo Paone, at L’Aquila.
The team researchers have been investigating on alternative ways for buildings to waste less energy. The result is the consecution of a new facade system with Peltier cells, that is to say, a new system of air conditioning that works both as a machine as a facade. That means the application in the field of construction of a technology that is already in use in other areas, fundamentally the military and aerospace. The new system has to be a prefabricated element that perfectly fix between the slabs. The result of all these ideas is the construction of a prefabricated module, consisting of a simplified inhabited housing unit with a thermoelectric installation that provides service to this module. The prototype has been monitored during one year. The University of Navarra has got the national patent for a ‘prefabricated and decentralized facade module for the climate control of inhabited spaces’. Moreover, the Thermoelectric Conditioning System TCS is designed to reach a high comfort level for people living in the local. Without mechanical parts like pumps or compressors, there is no necessity for maintenance, reducing the possibilities of failure. The only mechanical elements are the dissipation heat fans placed in the external face of the prototype. There are also some heat sinks to evacuate the heat from the power elements. The next step is improving the system as a facade, paying special attention to carry out the legal façade envelope’s requirements, such us, noise level, thermal transmittance, hydrothermal condition or behaviour against fire… At the same time, it is going to be design a facade solution that tries to take advantage of inside and outside conditions in order to achieve the desire inside comfort conditions. Furthermore, the module is going to integrate photovoltaic panels to achieve a total autonomy system, which does not need to be connected to the traditional electrical network.
It is an important task to qualify and rank residential buildings based on various priority aspects and to make optimum allocation of the material resources available for the renewal of the buildings. To this end a model based on fuzzy logic was prepared. To construct and to test this model many detailed technical-static expert reports were available all related to a stock of residential buildings in Budapest. Based on this report a database was created. With the help of this database a model was prepared, calculating a so-called status characteristic value between 0 and 1 on the basis of the structures and status of the buildings. For this calculation a fuzzy singleton signature model was prepared. Based on this a hierarchy can be set up related to the stock of buildings, which is suitable for supporting the decision-making on intervention. The model was examined by using the created database. Membership values characterising the status of the load-bearing structures – were defined on the basis of the deterioration of the structures. In this paper a new method for the determination of the membership values is described, which in addition to the deteriorations of the structures takes into account other parameters of the structures, and the impact exerted on the quality of the structure, too. The method is suitable for the determination of the membership values of all primary and secondary structures. As an example the membership values of the foundation structures of the buildings in the database were defined and the results were analysed. The method was elaborated by the use of ‘real fuzzy values’ (R-fuzzy sets), an extension of the concept of classic fuzzy sets, the former being suitable for simultaneously taking into account various aspects text.
