Pont en arc | EPFL Graph Search

vignette|Pont en maçonnerie sur l'Antietam, un affluent du fleuve Potomac. vignette|Ponts en arc dans le centre-ville d'Amsterdam. vignette|Le pont Maximilien-Joseph à Munich. vignette|Le pont Gebsattel à Munich. vignette|Les Satsop River Bridges dans l'État de Washington. Un pont en arc est un pont, à savoir une construction qui permet de franchir une dépression ou un obstacle (cours d'eau, voie de communication, vallée, ravin, canyon), dont la ligne de la partie inférieure (intrados), est en forme d'arc. Dans ces ponts, l'ensemble des charges permanentes ou temporaires appliquées au pont est repris dans l'arc en compression pour être transféré sur les appuis en rives, les culées. Classification Les ponts à voûtes Les ponts à voûte font partie de la famille des ponts en arc, par leur forme, mais ils constituent une famille à part, autant par leur calcul, qui relève de la théorie des voûtes, que par leur procédé de construction. Leur appellation usuelle est pon

Capacité portante de ponts en arc en maçonnerie de pierre naturelle

Alix Grandjean

Historical masonry arch bridges are an integral part of our cultural heritage and deserve the attention and the efforts required to safeguard their patrimonial value. There is currently a diverse range of methods available to engineers for evaluating the load-bearing capacity of masonry arches. The major drawbacks are that these methods are either too conservative or computationally intensive. The study presented here proposes a model based on the theory of plasticity. The result is a transparent model that is both rapid and easy to use. Moreover, its application does not involve heavy computation tools. The model is validated by comparison with available experimental results and with the results of a widely-recognised analysis software. In order to take into account the material and structural behaviour of an arch in an optimal way, the present thesis provides a new integral model divided into three evaluation levels. At the micro-level, the response of masonry under pure compression is used to characterise the material of an arch. At this level, numerical models are used to describe the behaviour of natural-stone masonry. These models distinguish between the constitutive units and mortar as well as the unit – mortar interface. The shape and arrangement of the units have the most influential role in defining the failure mode in comparison to the properties of each constitutive material. At the meso-level, the material behaviour from the preceding level is used to define the limit for the local plastification of an arch section under combined compression and flexure. This phenomenon is described as the formation of a hinge. The resistance of an arch section can be expressed using the bending moment – normal force interaction diagram based on the stress-strain curve of the masonry material. Each point along the interaction diagram refers to a state of stress causing the local plastification of an arch section due to the formation of a hinge. The macro-level focuses on the structural analysis of a masonry arch – a structure with four degrees of indeterminacy. The arch failure corresponds to the successive formation of four hinges defined by the yielding condition determined at the meso-level. The analytical model developed in this study considers an arch at the state of being a statically determinate structure – after three of the four hinges are developed. Using the principle of equilibrium, the model calculates the load-bearing capacity of the arch at the ultimate limit state. A large number of existing natural-stone masonry arches include deficiencies accumulated throughout years of service without any regular maintenance. Three common types of deficiencies on these bridges are considered. The model is extended to take into account their effects on the load-bearing capacity of arches. Finally, the model developed in this study is incorporated into a global methodology for the examination of masonry arch bridges. This methodology implies two complementary approaches, which have to be applied parallel to one another. The first uses the developed model and gives a quantitative evaluation of structural security. The second includes a qualitative appreciation of the risk, based on the condition survey of the structure. This methodology allows an objective examination of the structure and recommendations for intervention measures.

EPFL2010

Establishing stress-strain relationship for natural-stone masonry

Alix Grandjean

The conservation of historical monuments and especially natural stone masonry arch bridges is an issue which is becoming increasingly important. The prerequisite for any analysis of the load carrying capacity of such stonework is a precise knowledge of its material behaviour. This includes the stress-strain relationship for the natural stone masonry considered as a continuum, with all its important characteristics, such as nonlinearities in the pre-peak and softening behaviour in the post-peak domain. Natural stone masonry is a heterogeneous and anisotropic material which takes many different forms, ranging from rubble to ashlar masonry. Its mechanical behaviour is clearly influenced by its various characteristics. This paper investigates the influence of various parameters such as masonry type, bond, stone type and thickness of joints influence the stress-strain curve of natural stone masonry. It is also shown how stress-strain relationships originally established for brickwork masonry can be adapted to describe the behaviour of other types of stone masonry. Finally, application of stress-strain relationship to predict the load carrying behaviour of natural stone structural elements such as arches will be outlined.

Uni Stuttgart2008

Load-bearing capacity of masonry arch bridges using a plastic model

Eugen Brühwiler, Alix Grandjean

Determination of the load-bearing capacity of natural-stone masonry arches is an important aspect in the field of conservation of architectural heritage. Structural verification of bridges of this type requires thorough methods in order to make efficient use of the considerable reserve commonly found in their structural capacity. The failure of these structural elements often involves successive formation of hinges until failure. The present study aims to establish a novel analytical model to evaluate the load-bearing capacity of stone masonry arch bridges. The model takes into account both the non-linear behaviour of masonry and the high ductility of such arches. Furthermore, the analysis considers the effect of typical deficiencies of masonry arches on their load-bearing capacity. The application of the developed model is illustrated in a case study.

CRC Press/Balkema2009

Capacité portante de ponts en arc en maçonnerie de pierre naturelle

Alix Grandjean

EPFL2010