Construction en pierre massive en Suisse

«For me, to build an air terminal with stone would be a stupidity, not to say a madness. But to use dynamic structures to fit three-roomed flats with kitchen in buildings from three to ten floors, is not less aberrant.»1 Provocation of a reactionary architect or a lucid analyze of the world of the construction of his time, this assertion of Fernand Pouillon still preserves, forty years after, its value of interrogation on the use of the natural stone. Indeed, since the industrial revolution and the introduction of new construction materials, like concrete and steel, the natural stone was gradually confined in the sphere of the noble claddings. If we look at behind, on the other hand, until the 19th century, we realize that the situation was very different, as well the use of this material as its social status. The stone was, and it still is, thanks to its great durability, the principal constituent part of the built environnement: public buildings, simple rural buildings, civil engineering works, cadastral limits and limits of properties, all were made out of natural stone, a material largely available locally, at least in our countries, and whose exploitation required reduced energy investments. The local builders knew, in an empirical way, the characteristics of the rocks they had as much to facilitate their extraction, by exploiting the natural fractures and "weaknesses", as for their selection. Thanks to their resistance to the atmospheric agents, increased by the strong thicknesses used, the cut stones could be employed again. The investment in work and energy was thus amortized on several generations. An adequacy between the resource, the exploitation and the techniques occurred naturally. In a slow evolution, the natural stone arrived until the industrialization of the processes of exploitation and shaping and allowed in France, in the years of the post-war period, to rebuild cheap blocks of flats by using a "pre-cut stone" with standardized dimensions. After the end of this "adventure", the use of natural stone in massive form slowly disappeared, to reappear in the years 1990, when the French architect Gilles Perraudin started to employ again dimensional stone, simply cut in the quarry, for the construction of buildings of various use. Our PhD thesis fit into the tradition of the experience of Fernand Pouillon. Indeed, today, at the era of sustainable development and the energy diaries, the use of natural stone as building material should be restored. Accordingly, we treat in this research the case of massive stone construction in Switzerland. While following the course which leads the natural stone of the mountain to the building, we tried to define a method to use dimensional stone in the current construction industry, while respecting the current constraints as regards durability, seismic safety and reduction of energy consumption. We thus tried to show that the natural stone can continue to be regarded as a whole construction material, and this by using the scientific checking, new in this form, of practices well consolidated by the centuries. In a restricted territory like Switzerland, all the principal families of rocks are present. The reduced distances make it possible to consider their use with regional scales, even national. The builder thus sees himself obliged to know their geological, petrographic and technical characteristics in order to be able to select them, since the properties of the material influence its behavior in the building as much at the static level as of durability, but also they determine the techniques which are employed to extract it from the deposit and to shape it. Indeed, before being employed, the rock must become dimensional stone: the exploitation of the quarry, its contemporary techniques as well as the various forms of shaping require to be known and analyzed. These processes do not influence only the dimensions of the stones, but their cost as much for energy as financial. In the second chapter of this research, we study the exploitation of the natural stone quarry. The empirical knowledge acquired during the field visits as well as the scientific data produced by the laboratory tests, that almost each producer currently has, enabled us to select the Swiss rocks for the massive construction and to collect them in all-encompassing cards. Moreover, the availability of natural stone is the essential condition to consider its use in the construction industry. The management and the restoration after exploitation of quarries are treated as much at the environmental level as of regional development. The knowledge acquired on the natural stones, their characteristics and their exploitation is used by the builder to define their use in building. This one does not follow simply from constructive or static criteria, but, today, also from seismic resistance, thermal comfort, lifespan and durability. We propose in our work to use the dimensional stone masonry for three types of constructions: load-bearing structure for buildings; self-supporting cladding for façades and load-bearing structure or cladding for retaining walls. In all these cases, we envisage that the project is carried out in an adequacy between the rock, its modes of exploitation and the current constructive requirements, in order to demonstrate the topicality of this ancestral material. ________________________ 1. Pouillon, F. 1968: Mémoires d'un architecte, Paris, Editions du Seuil, p. 174.

The politics of participation in transdisciplinary sustainability research: an analysis of knowledge, values and power at the science-society interface

Livia Bianca Fritz

Problem. In the field of sustainability, scholars and policy-makers herald the transformative power of participation in transdisciplinary (TD) research. The increasing use of TD in science policy is rooted in the expectation that involving practitioners in the research process produces 'socially robust' knowledge and fosters the desired societal change. However, there is a strong discrepancy between these expectations, ideal-typical conceptions of TD, and a limited understanding of the complex interactions that forge participation in knowledge production practices. Aim. This thesis aims to enhance understanding of the complex processes that shape participation practices and their outcomes in TD sustainability research. Methods. This thesis links social theories and literature from sustainability research, Science and Technology Studies, and development research with empirical enquiries into the making of participation. Qualitative and quantitative methods are combined in order to draw a rich picture of researchers' and practitioners' perceptions of participation processes and outcomes. Results. To begin, this thesis offers a novel perspective on participation as a relational space that is dynamically forged through the interplay of structures and processes. Secondly, it identifies structural and actor-related elements that constitute participation spaces, including: (in)coherence with reference systems, resources, timing, expectations, trust, values and power relations. The empirical analyses show that funding bodies, researchers, and practitioners exercise 'power over' actor selection, as well as agenda and rule setting, leading to the exclusion of some knowledges and values. Throughout TD processes, 'power over' intersects with 'power with' and 'power to', highlighting trade-offs between the epistemic and societal goals of participation. Unpacking processes also shows how partly incommensurable values with regard to sustainability shape knowledge production, and how the latter can perpetuate dominant discourses on society-nature relations. Finally, this thesis reveals diverse participation-effect pathways as well as feedback effects. Researchers' and practitioners' diverging perceptions of pathways come with contrasting roles and responsibilities they ascribe to themselves and to others. Conclusions. The results demonstrate that participation processes in TD sustainability research are not only a matter of techniques and methods, but also of political endeavours that must be placed in a broader socio-political context. The value negotiations and power relations that form them, the multiple purposes for which they are mobilised and their role in the governance landscape demonstrate the importance of the politics of participation. Fostering conceptual clarity and empirical knowledge of the dynamics that shape participation in and the effects of TD research, this thesis feeds into a critical sustainability scholarship that is aware of power dynamics and is reflexive towards its own practices. It provides researchers and practitioners with theoretically and empirically-grounded analytical perspectives and guiding questions on the role of structures, actors and power relations in TD practice. These tools allow for unravelling the deep-rooted challenges of participation and support researchers and practitioners in making their assumptions about pathways to societal change visible and negotiable.

EPFL2020

Changes in Employment Localization and Accessibility

Pierre-Emmanuel Dessemontet

Until about the end of WWII, the territorial organization of the economy could be expressed along a very strong center-periphery gradient, with industries and services concentrated in cities while the countryside supplied agricultural products. Since the industrial revolution, industrial regions had emerged essentially in mining regions which perturbed this very simple scheme, but without fundamentally modifying it. In the first half of the 20th century, with the advent of mass transportation and of the individual car, the residential functions started to deconcentrate and residential suburbs developed. However, as a general rule, most non-agricultural economic functions remained tightly attached to the city core and its immediate surroundings, and with them their jobs. These structures were accounted for by various theoretical models, of which the Von Thunen land-rent model family, the Weber models of industrial localization and regional specialization, and the Christaller model of hierarchical city networks were the most prominent. However, since 1945, those jobs have seen their territorial distribution shift. First, the importance of agriculture dwindled, to the profit first of industrial activities, then of services. Land-hungry activities, such as the industry and logistical activities vacated the urban centers in search for ample space, which they generally found in suburban settings under the guise of industrial zones. But they weren't alone at deconcentrating. Retail and personal services tended to follow their customers in the suburbs. During the last quarter of the 20th century, selected suburbs evolved from purely residential or industrial functions to more complete economic ones, integrating retail, high tech and professional services. By 1990, the phenomenon was largely recognized in North America, where those job-intensive suburbs were nicknamed edge cities. Empirical studies showed convincingly that the same patterns of job and functional deconcentration were found in the whole world and especially in western countries. Job suburbanization is contemporary with major spatial and functional economical upheavals. The economy, for instance, evolved from the fordist integrated economical model dominated by very large companies internalizing most of their functions in a vertical, hierarchical relationship pattern to a post-fordist disintegrated model where companies concentrate on their core competencies and subcontract in a horizontal, contractual manner their non-core needs. Economical spatial deconcentration is also contemporary with the current version of globalization, materialized by the emergence of global cities and metropolises which keep constant communication flow between themselves, in a horizontal manner, and which are less and less dependent on their hinterland for their economical survival and development. Likewise, the economy becomes more and more informational, relying on knowledge, immaterial services, instant worldwide communication, and the production of sophisticated products for which worldwide shipping costs became negligible, and for which the location needs shifted from access to markets to access to qualified workers. While globalization, metropolization and the post-fordist economical transition have been thoroughly studied, job suburbanization has not been the focus of such an interest from the scientific community. Consequently, we lack empirical evidence and theoretical advances which would help us to better understand how the economy spatially evolved since 1945 and where the world is heading if the trends seen since 1945 are maintained. The prime goal of this work is to provide a better understanding of the way the economy spatially evolved at the intra-metropolitan scale, based on the example of Switzerland, a fairly exemplary western country. The work is divided in three major parts – an introductory one, an empirical one, and a inferential one. The core hypothesis of this work is that as the individual car became ubiquitous, proximal relations were progressively supplanted by accessibility relations. We surmise that job distributions and their evolution can be explained by accessibility patterns and change, which are in turn dependent on a number of factors – the population distribution, the structure and state of the road network, the state of the car technology, and the time commuters are ready to travel to go to work. The first three chapters aim at defining our object of study in chapter 1, to give an understanding of the country on which we will be working and of the data at our disposal in chapter 2, and a working definition of what constitutes a job center in chapter 3, where major distinctions between urban, mixed, suburban, exurban, touristic centers and edgeless space are introduced which accompanies us for the rest of the work. The next four chapters constitute the empirical part of the work. Chapter 4 seeks at describing as precisely as possible the territorial evolution of the Swiss economy since WWII, studying it at nine different points in time from 1939 to 2008. Chapter 5 takes a long-term view of the same series of data and seeks to detect, describe and explain the trends which are unearthed by this larger view. Chapter 6 concentrates on the latter half of the period under review and studies the distributions along more precise branch divisions, as well as miscellaneous other classifications according to added value and productivity, interaction needs, job qualification and creativity. Chapter 7 concentrates on the command and control structure of the economy as seen through the spatial relations entertained by headquarters and their subsidiaries, by Swiss and foreign multinationals, by the public and private sector. Finally, chapters 8 and 9 undertake the inferential part of our work, and aim at testing our core hypothesis of a statistically demonstrable link between accessibility, which is defined and thoroughly studied in its historical dimension in chapter 8, and a measure of job quality. Chapter 9, the last of the work, takes this core hypothesis to the statistical test. The results of this work are multiple. First of all, it shows that the spatial structure of the economy indeed transitioned from a very strong center-periphery organization in 1939, when two thirds of all non-agricultural jobs were located in urban centers, about a quarter in the country-side and the rest in numerous small industrial villages, to a vastly different structure in 2008 with less than half such jobs located in urban centers while suburban centers capitalize about a quarter of them, the rest being distributed mainly in edgeless space – industrial villages having somewhat lost in importance. This work shows that the spatial components of the economical structure have also greatly evolved. While in 1939 urban centers concentrated most of the economic functions and all of the commanding ones, spatial specialization has been relentless since then, and especially since the last quarter of the 20th century. Suburban centers have grown, but also gained in quality, especially in the high tech and the professional services sectors, and in commanding functions: as of 2008, they hosted more jobs in headquarters than in subsidiaries. In parallel, cities have tended to specialize on some key sectors of the economy: finance and governmental services at large, accompanied by personal services catering for the new urban elite. Taken altogether those developments pick at the prevailing spatial economic theories and show a major departure from the Christallerian model. Anecdotal evidence shows that by and large suburban centers seem not located haphazardly in the larger suburban belt, but are concentrated on several specific point within it, namely the higher accessibility areas, especially highway junctions and interchanges. This hints at the possibility that high accessibility is a determinant of job localization. In the course of this work we demonstrated first that accessibility is more dependent on road network changes that to other parameters such as population distribution, technological changes and attitude changes towards commuting, and that the accessibility changes due to road network evolutions display far stronger local accessibility gradients. Secondly, we demonstrated the existence of a link between accessibility and job density taken as a measure of job quality, after taking into account the effects of spatial autocorrelation. Much of the unexplained variance shown by a global regression model can be modeled away as regional effects when using a geographically weighted regression, so that the combination of regional effects and accessibility accounts for a major part of the job density variance. Finally, the introduction of time lags between accessibility conditions and job densities hinted at the possibility that a causal link exists between the two, accessibility changes preceding, and maybe then causing, job density changes: in short, this work shows that accessibility by car is a major determinant of job localization.

EPFL2011

Alexandre Sarrasin (1895-1976) et l'esthétique de l'ingénieur

Philippe Mivelaz

Alexandre Sarrasin (1895-1976) studied at Zürich Federal Swiss Institute of Technology (ETH) from 1913 to 1918. Despite First World War's conflicts surrounding the neutral Switzerland, the intellectual climate inside ETH was cosmopolitan and liberal. As unique educational institution directly depending from the Federal government, the ETH played an important role in shaping modern Switzerland where country planning and infrastructure building were the central power's main tasks. Engineers were important figures of this process of modernization. They embodied the values of the industrial revolution: rationality, efficiency and the huge power of transformation of the country and its society. Sarrasin opened an engineer's office in Lausanne in 1921 and in Brussell two years later. He established himself in the capital of Belgium in 1927 while ruling at the same time his office in Lausanne. He came back to Switzerland when the German army invaded Belgium. The office in Bruxells was maintained up to the early 1960's. Branches were opened in Sion and Geneva during the 1950's. Sarrasin's work concerned foundations, buildings, bridges and some dams also. Nearly all these constructions works were made of reinforced concrete, his favorite material. This thesis is dedicated to the construction works, especially the bridges in Valais, Sarrasin's native district, and the aesthetic question in engineer's design. Of the bridge of Branson (1924- 1925) near Fully, his first important commission, he wrote that "The elegance of the design is due to its simplicity. The quietness of its lines is fully harmonized with the landscape. Nothing was planned for the decoration. The bridge is the simple realization of a mathematical truth". This quotation highlights the issue of form for engineers and especially in Sarrasin's works: the affirmation of simplicity and "mathematical truth", that is to say the expression of the structural mechanics, as the engineer's aesthetic's fundamental the relation with the landscape The question of form was not only thought of in terms of efficiency and economy, or lack of decoration. The development of structural mechanics as engineer's science gave new conceptual tools allowing new designs. The first professor of civil engineering at the ETH, Karl Culmann (1821-1881), was the graphical static's father. This applied science was inspired by descriptive geometry and graphical calculation methods developed in France during the 18th and 19th century. To the construction's classical point of view distinguishing between elements bearing weight (for example pillars) and others being supported (for example lintels), graphical static opposed a spatial vision of forces interactions into the structure. New materials allowed bringing these forces into play with tensed cables, compressed or extended frames. At the beginning of the 20th century, reinforced concrete appeared as modern material along side with iron and steel. Created by builders in the 19th century, its construction method was investigated by engineers making it a universal material used by everyone, independent of patents. This assimilation was made by elaborating construction norms that had sometimes inhibitive effects on the creativity of engineers. Other engineer looked for new forms fitting the material's caracteristics. Robert Maillart (1872-1940) was one of them. He had a great influence on Sarrasin's work. The first half-century of modern engineers which started with the creation of the ETH in 1855, was a period of great innovations in science and technology. Most construction works were made of metal and were built for the railways and designed with the graphical static, creating a new architecture, but the question of aesthetic became an issue only at the beginning of the 20th century. The first reaction rose against the overwhelming presence of technology in surroundings : its impact on the landscape or on the city's image was depicted as negative. At the same time, other observers – architects, art historians – recognized in industrial constructions an aesthetical value. Some engineers wanted a come back to traditional forms as stone vaults. During the first quarter of century, several metallic bridges had been considered as fragile and replaced by stone works. Bridges were designed as monuments. On the other side, some engineers argued for the beauty of modern materials and technology, opposed to the picturesque point of view, represented by those who wanted preserving the landscape. The First World War was not only the beginning of the 20th century. It seemed also to be the moment where engineers lost their innocence. Aesthetical questions and the impact on the landscape were matters of public debates. During the same period engineering became a profession free of contractors. That had probably the effect that engineers developed their own language. Sarrasin exactly spent his study years during this period of changes. Matters of aesthetic belonged to the themes treated by his professor of structural mechanics, Arthur Rohn (1878- 1956), who considered that a bridge should not only be built rationally, but should also express his structural system. François Schüle (1860-1925), who was involved in developing constructive norms for reinforced concrete, was his professor of material's technology. He represented the scientific side of the profession of engineer. The works of Sarrasin embodied this double requirement for rationality in using materials and the will to integrate the construction works into the landscape and into the environmental context. Valais was the landscape taken into account. This mountainous district entailed contradictory representations of the need of modernization and the preservation of landscape and traditions. On one side, this region was shown as a society preserved from modernity with unchanged traditions, on the other side, the Valais quickly took part in the national economy. The landscape changed deeply with the draining of the main valley of the Rhône river, the construction of rail and road nets, industry and hydroelectric plants. Sarrasin's works were the products of this economic revolution which transformed the Valais region; they wanted at the same time to be a testimony of this story. One of the interesting aspects of the attitude of this engineer is the way he used references to ancient constructions. Beamers and arches reconsidered in respect with modern technology by use of reinforced concrete, created a dialogue with the landscape or with stoned vaults thrown upon the Alps deep abysses.

EPFL2007