Abutment | EPFL Graph Search

An abutment is the substructure at the ends of a bridge span or dam supporting its superstructure. Single-span bridges have abutments at each end that provide vertical and lateral support for the span, as well as acting as retaining walls to resist lateral movement of the earthen fill of the bridge approach. Multi-span bridges require piers to support ends of spans unsupported by abutments. Dam abutments are generally the sides of a valley or gorge, but may be artificial in order to support arch dams such as Kurobe Dam in Japan. The civil engineering term may also refer to the structure supporting one side of an arch, or masonry used to resist the lateral forces of a vault. The impost or abacus of a column in classical architecture may also serve as an abutment to an arch. The word derives from the verb "abut", meaning to "touch by means of a mutual border". Use An abutment may be used to transfer loads from a superstructure to its foundation, to resi

Interaction sol-structure dans le domaine des ponts intégraux

Damien Dreier

Over the past decades, an increasing number of integral bridges have been built. This type of bridge offers various advantages in comparison with standard bridges equipped with expansion joints and bearings. In particular, integral bridges require less maintenance since they have less mechanical elements. Therefore, cost of retrofitting and indirect costs such as time spent by users during the maintenance works is reduced. Moreover, the static efficiency is increased and the noise of circulation during its lifetime is reduced. However, for the design and analysis of this kind of structure, the soil-structure interaction needs to be investigated to take in account the monolithic behaviour of the bridge with the embankment near the abutment and the piers with the foundation. This interaction is complex and further research is needed. The report begins by a general introduction of the topic. Thereafter a brief description of the state-of-the-art on integral bridges is presented, as well as the main difficulties faced during design and the main actions that need to be considered. Limit states and numerical analysis on integral abutments and pier on shallow foundations are discussed towards a better understanding of the structural behaviour in order to improve current detailing and design practice. The study of integral abutments shows that soil-structure interaction should be considered at early stages of the design process. This allows introducing small geometric adaptations to improve detailing which in turn allows significantly increasing the long term performance of the integral abutment without a sensible increase of building costs. This set of new rules can further be applied to both new and existing bridges which require retrofitting of the expansion joints at the abutments. The study of the cracking limit state of piers shows the strong influence of the geometry of the shallow foundations on the soil-structure interaction. This two studies show that geometric adaptation in combination with accurate soil-structure modeling could lead to an increase of the current Swiss limit length for integral bridges which is now set at fixed to 60m.

EPFL2010

Toe protection for spill-through and vertical-wall abutments

António Heleno Cardoso, Anton Schleiss

This study addresses the design of riprap aprons as a scour countermeasure near abutments under clear-water conditions. It deals with the lateral extent of riprap aprons and the geometry of the scour hole prevailing at the apron edge. The study applies to riprap aprons acting as granular filters. The scour depth appears to be independent for a sufficiently long relative abutment length. Scour holes develop farther away from spill-through abutments than from vertical-wall abutments; the distance between the point of maximum scour depth and the abutment increases with the relative abutment length. The effect of contraction on this distance was not identified. The angle defining the position of the deepest scour point is close to 308. Neither the abutment shape nor the flow contraction seems to influence the minimum stable apron width.

2010

Sizing of riprap for spill-through abutments

António Heleno Cardoso, Anton Schleiss

An experimental investigation of riprap stability at spill-through abutments has been carried out in two similar horiontal-bed flumes, avoiding riprap failure modes other than shear failure and erosion failure. Tests were conducted for two common abutment side slopes, subcritical flow regime, short to intermediate abutment lenghts and high bed roughness. The aim of the experiments was to determine the size of stone riprap necessary to resist (a) shear failure in aprons placed at the base of spill-through abutments, and (b) erosion failure over their side slopes. Results are compared with predictions of stone riprap size given by expressions found in the literature. The predictor of Pagan-Ortiz is confirmed as being appropriate for shear failure at abutment aprons and can be adapted to account for erosion failure over abutment side slopes. Alternatively, two news expressions, written in terms of the (critical) approach flow intensity required to make the riprap stones move, are suggested.

2010

Interaction sol-structure dans le domaine des ponts intégraux

Damien Dreier

EPFL2010