Carlos Chastre

Abstract Sandstones are widely used in the building elements of the world’s stone monuments. Alveolization due to salt crystallization-dissolution is the most important degradation pattern found on the Middle Ages’ sandstone façades of St. Leonardo’s Church in Portugal. An outstanding case of widespread distribution of deep and large alveolization patterns found mainly on portals and vaults of its sandstone façades appeared as a result of the past and present proximity of the seashore. On stonewall façades, a new approach of consolidating products’ treatments using the total head was followed in order to allow full absorption of stone. Physical and mechanical tests were carried out on selected representative specimens of varieties of sandstones on the monument. Treatments with ethyl silicates were assessed by means of its effectiveness, harmfulness, and durability. The comparison of results between the application of this new procedure on this stone monument and the traditional intervention treatments highlighted the potential viability of the former to overcome difficult conditions of absorption of consolidating products.

Earthquakes, soil settlements, traffic vibrations, and air pollution are some of the actions that can affect historic old buildings. Besides these, the lack of continuous maintenance puts a large part of this heritage in risk due to structural problems that reduce their own safety and that of their users. The preservation and risk mitigation of built cultural heritage require the use of reliable tools in order to assess its state of conservation and to identify and prevent potential vulnerabilities. Having this in mind, it is not possible to carry out destructive tests in most historic old buildings, so it is preferable to opt for nondestructive tests (NDT) or alternative methodologies that allow the physical and mechanical characterization of materials and structure. In this chapter, a general view of NDT methods used in historic buildings to obtain the geometrical information, the damage mapping, the mechanical and physical characterization, and the petrographic analysis of stones is presented. An alternative methodology to physically and mechanically characterize the stone of historic buildings using NDT tests is also proposed. The chapter ends with a case study carried out in the St. Leonard’s Church, a Portuguese monument built in Atouguia da Baleia village in the 13th century, where the alternative methodology here presented was applied. The final results of this study show that the methodology proposed allows the obtention of stress-strain curves in a completely nondestructive way, based on the water absorption coefficient at low pressure.

Precast concrete sandwich panels started being used as cladding for buildings, together with the rise of industrial prefabrication, during the mid-20th century. Since then, society and industry have become increasingly aware of energy efficiency in all fields, for both affordability and sustainability consciousness. As such, buildings have been subject to increasingly stringent requirements with the technology of sandwich panels kept continually at the forefront.
Nowadays, sandwich panels have reached the highest standards of functional performance as structural efficiency, flexibility in use, the speed as well as of aesthetic appeal. These combine in building construction with the well-known advantages of prefabrication; such as construction, quality consciousness, durability and sustainability. Sandwich panels have gained more and more important in their field, thus representing quite a significant application within the industry of prefabrication and an important share of the market.
The Commission ‘Prefabrication’ is keen to promote the development of all precast structural concrete products and to transfer the knowledge to practical design and construction. Now filling a strategic gap, by issuing this Guide to Good Practice, which includes design considerations, structural analysis, building physics, use of materials, manufacturing methods, equipment, field performance, and provides a comprehensive overview of the information currently available worldwide. The Commission is particularly proud that this document is a result of close cooperation with PCI and that it will be published by both fib and PCI. This cooperation started six years ago, first with comparing the different approaches to several issues, then progressively integrating up to producing common documents, like this one, that wasn’t yet treated in a specific Guide by either body.

Weathering imposes vital effects on stony monuments. Mostly, the degree of weathering is determined by simple test results, ignoring simultaneous effects of various weathering factors. Hence, the main purpose of this study is to develop prediction models with fuzzy inference systems to determine the weathering degree of the Persepolis stone, using various accelerated ageing tests in laboratory condition and to extrapolate the results to the natural condition, considering climatic information. The results suggest reliable conformity between the prediction of the weathering degree of the stone and the weathering degree observed in the Persepolis complex in natural condition.

Measurements in civil engineering load tests usually require considerable time and complex procedures. Therefore, measurements are usually constrained by the number of sensors resulting in a restricted monitored area. Image processing analysis is an alternative way that enables the measurement of the complete area of interest with a simple and effective setup. In this article photo sequences taken during load displacement tests were captured by a digital camera and processed with image correlation algorithms. Three different image processing algorithms were used with real images taken from tests using specimens of PVC and Plexiglas. The data obtained from the image processing algorithms were also compared with the data from physical sensors. A complete displacement and strain map were obtained. Results show that the accuracy of the measurements obtained by photogrammetry is equivalent to that from the physical sensors but with much less equipment and fewer setup requirements.

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In 1994 fib Commission 6: Prefabrication edited a successful Planning and Design Handbook that ran to approximately 45,000 copies and was published in Spanish and German.Nearly 20 years later Bulletin 74 brings that first publication up to date. It offers a synthesis of the latest structural design knowledge about precast building structures against the background of 21st century technological innovations in materials, production and construction. With it, we hope to help architects and engineers achieve a full understanding of precast concrete building structures, the possibilities they offer and their specific design philosophy. It was principally written for non-seismic structures.

The handbook contains eleven chapters, each dealing with a specific aspect of precast building structures.
The first chapter of the handbook highlights best practice opportunities that will enable architects, design engineers and contractors to work together towards finding efficient solutions, which is something unique to precast concrete buildings.
The second chapter offers basic design recommendations that take into account the possibilities, restrictions and advantages of precast concrete, along with its detailing, manufacture, transport, erection and serviceability stages.
Chapter three describes the precast solutions for the most common types of buildings such as offices, sports stadiums, residential buildings, hotels, industrial warehouses and car parks. Different application possibilities are explored to teach us which types of precast units are commonly used in all those situations.
Chapter four covers the basic design principles and systems related to stability. Precast concrete structures should be designed according to a specific stability concept, unlike cast in-situ structures.
Chapter five discusses structural connections.
Chapters six to nine address the four most commonly used systems or subsystems of precast concrete in buildings, namely, portal and skeletal structures, wall-frame structures, floor and roof structures and architectural concrete facades.
In chapter ten the design and detailing of a number of specific construction details in precast elements are discussed, for example, supports, corbels, openings and cutouts in the units, special features related to the detailing of the reinforcement, and so forth.
Chapter eleven gives guidelines for the fire design of precast concrete structures. The handbook concludes with a list of references to good literature on precast concrete construction.

A indústria do betão pré fabricado é, por tradição, inovadora, precursora de novas tecnologias e de novos materiais.O processo produtivo de estruturas com elementos pré-fabricados difere significativamente do das estruturas betonadas em obra pelo facto de uma parte, ou a totalidade, dos elementos da estrutura serem produzidos em fábrica, em condições de produção melhoradas em relação às condições da obra, e serem posteriormente transportados para a obra, onde são, finalmente ligados entre si. A produção em fábrica é efectuada em ambiente protegido do Sol e da chuva, com operários fixos e com formação profissional para desenvolverem tarefas com procedimentos normalizados. Consequentemente, os elementos executados em fábrica possuem melhor qualidade, sob vários aspectos, do que as estruturas executadas em obra.Este livro divide-se em duas grandes áreas, numa primeira abordam-se algumas aplicações de estruturas pré-moldadas no mundo e numa segunda parte descreve-se o seu comportamento estrutural face a diferentes acções. Nos primeiros capítulos relata-se a experiência da pré-fabricação em três países de diferentes continentes: o Brasil, Portugal e a Austrália e revelam-se novas oportunidades que poderão surgir para a indústria da pré-fabricação. Nos capítulos seguintes dá-se um especial enfoque à investigação do comportamento das ligações (rígidas e semi-rígidas). Aborda-se o projecto de estruturas de betão pré-fabricado às acções acidentais. E por fim, dedicam-se os últimos capítulos ao comportamento das estruturas pré-fabricadas face às acções sísmicas. Nesta área, o bom desempenho das estruturas e grande parte do conhecimento e da tecnologia actual advém da resposta dada pelos engenheiros, investigadores e construtores aos fenómenos naturais que afectam as nossas construções, como comprova o desempenho das ligações dúcteis resistentes a momentos em edifícios pré fabricados de betão no verdadeiro teste sísmico que foram os sismos de Christchurch de 2010 e 2011.

Since the 1980’s, several buildings throughout the world have been subject to gas explosions, impact by cars or airplanes, or car bomb attacks. In many cases the effect of the impact or explosion has been the failure of a critical structural member at the perimeter of the building. After the failure, the load supported by that member could not be redistributed and part or all of the structure has collapsed in a progressive manner. The phenomenon that occurs when local failure is not confined to the area of initial distress, and spreads horizontally and/or vertically through the structure, is termed progressive collapse.

Progressive collapse is a relatively rare event, as it requires both an accidental action to cause local damage and a structure that lacks adequate continuity, ductility, and redundancy to prevent the spread of damage. It is technically very difficult and economically prohibitive to design buildings for absolute safety. However it is possible to construct precast concrete buildings that afford an acceptable degree of safety with regard to accidental actions.

A structure is normally designed to respond properly, without damage, under normal load conditions, but local and/or global damages cannot be avoided under the effect of an unexpected, but moderate degree of accidental overload. Properly designed and constructed structures usually possess reasonable probability not to collapse catastrophically under such loads, depending on different factors, for example: the type of loading; the degree and the location of accidental loading in regard to the structure and its structural members; the type of structural system, the construction technology, and the spans between structural vertical members, etc.

No structure can be expected to be totally resistant to actions arising from an unexpected and extreme cause, but it should not be damaged to an extent that is disproportionate to the original cause.

The aim of fib Bulletin 63 is to summarize the present knowledge on the subject and to provide guidance for the design of precast structures against progressive collapse. This is addressed in terms of (a) the classification of the actions, (b) their effect on the structural types, (c) the strategies to cope with such actions, (d) the design methods and (e) some typical detailing, all supplemented with illustrations from around the world, and some model calculations.

The measurement of deformations, displacements, strain fields and surface defects in many material tests in Civil Engineering is a very important issue. However, these measurements require complex and expensive equipment and the calibration process is difficult and time consuming. Image processing could be a major improvement, because a simple camera makes the data acquisition and the analysis of the entire area of the material under study without requiring any other equipment like in the traditional method. Digital image correlation (DIC) is a method that examines consecutive images, taken during the deformation period, and detects the movements based on a mathematical correlation algorithm. In this paper, block-matching algorithms are used in order to compare the results from image processing and the data obtained with linear voltage displacement transducer (LVDT) sensors during laboratorial load tests of T-beams. © 2011 IFIP International Federation for Information Processing.

The traditional methodology used in civil engineering measurements requires a lot of equipment and a very complex procedure especially if the number of target points increase. Since the beginning of the current century, several studies have been conducted in the area of photogrametry using digital image
correlation associated with block motion algorithms to estimate displacements in reinforced concrete (RC) beams during a load test. Using image processing techniques it is possible to measure the whole area of interest and not only a few points of the tests materials. In this paper, block-matching algorithms are used in order to compare the results from photogrametry techniques and the data obtained with linear voltage displacement transducer (LVDT) sensors during the load tests of RC beams, which are very common to find in civil engineering laboratories.

The present work studies the behaviour of bonded steel plates to reinforced concrete elements, which can be used in the strengthening of concrete structural elements. Metallic expansion bolts can be added.The objective of this dissertation is to investigate the behaviour to monotonic actions and particularly to cyclic loading of steel-epoxy-concrete connection with expansion bolts. This cyclic action is of particular interest due to the strong seismicity of the Portuguese territory.The research is mainly based in experimental analysis. The caracterization of the materials was carried out. Six models of the steel-epoxy connection were tested with monotonic loading. Twenty six models of steel-epoxy-concrete bond were submitted either to monotonic or to cyclic actions.Besides the type of action, other parameters were studied in the steel-epoxy-concrete connection models.These were the bond geometry area, the type of concrete, the type of epoxy and connection - with or without metallic expansion bolts.A parametric study with a numerical model of finite elements, as well as a global analysis of the experimental tests of the steel-epoxy-concrete connection was carried out.