“ASSET has acquired an exclusive licence from BEBO Arch in Switzerland to sell BEBO concrete arch structures in the UK and Ireland since 2006. This provides ASSET’s customers a broader range of bridge solutions, complementing traditional products such as Multiplate and Stren-Cor.
Our first BEBO arch structure in the UK is for the Dobwalls Bypass project which is the first Significant Precast Concrete Arch built over major national rail line since Gerrard’s Cross Failure. Since then, we have had success in numerous major projects, providing value engineering solutions using BEBO arch. For example, Church Village Bypass, Weymouth Relief Road, A470 Cwmbach Relief Road, and many more.
Asset now also distributes BEBO concrete arches in Poland, Sweden, Finland and Norway.”
- BEBO® Concrete Arch System - Introduction
The BEBO Concrete Arch Bridge System from ASSET is a pre-engineered system built from factory-made components and site-specific construction materials. Pre-cast concrete arch sections are shipped to site for installation. The structure is backfilled with engineered granular material and finished off with wing walls, spandrel walls or other secure end finishes.
Standard sections are used to build a range of arch structures with spans from 4m to 30m. Structures can be designed to accommodate large live loads and/or high fills and can be installed quicker than conventional concrete bridge structures.
In the early 1960′s, the Swiss engineer Dr. Werner Heierli began the development of overfilled concrete arch systems. The objective was to build concrete arches with a minimum thickness, sufficient to carry the applied loads, but also stender enough for the passive resistance of the backfill to be mobilised by means of elastic deformations of the arch. With this concept, the fill could contribute to the load carrying capacity of the arch and become part of the structure rather than just representing a loading. This phenomenon, known as the “soil-structure-interaction”, is widely used in the BEBO design approach.
In 1965 the first BEBO arch was manufactured from 160 mm (6.3 inch) thick precast concrete elements. This arch was a proof of concept, full-scale experimental structure, constructed when the BEBO System was being considered for a whole series of underpasses for the Swiss highway system under construction at that time. The experimental structure more than verified the promising results of the theoretical analyses.
After the test, which successfully demonstrated the viability of the BEBO System, the first BEBO underpass structure was erected for service on a major highway near Zurich, Switzerland in 1967.
Since then, approximately 500 BEBO Arch structures have been built in Europe, North America, Australia and the Near East. All of these structures remain in service and have required virtually no maintenance to date.
The large number of structures completed, demonstrates that the pre-engineered BEBO System represents a feasible and economic solution for a wide variety of structures such as underpasses, under roads or highways and bridges over streams, waterways, roads and railway lines, and cut-and-cover tunnels.
- BEBO® Concrete Arch System - Construction
A typical BEBO® System bridge consists of the following elements:
BEBO® System arches are typically two-pinned arches of uniform thickness. They come as precast twin-leaf units.
Twin-leaf units are connected on site by means of a patented cast-in-place crown joint. The BEBO® System currently consists of the following standard arch sizes covering a span range from 3.66 to 25.60 metres (12 to 84 feet)
The two digits following the profile code indicate the clear span of the arch in feet (E = elliptical profile, C = circular profile)
- E12, E16, E20, E24, E30, E36, E42, E48 (single-leaf arches)
- E54T, E60T, E66T, E72T, E78T, E84T (twin-leaf arches)
- C30T, C36T, C42T (twin-leaf arches)
Each arch type is available with varying leg lengths, resulting in more than 100 standard arch types which are available with the BEBO® System.
The precast elements are normally manufactured, stored and transported on their sides.
Once on site, the elements are lifted, rotated and placed onto the key of the cast-in-place foundations. For the twin-leaf profiles, either two cranes, or one crane and a temporary support are used for the element installation.
BEBO® System arches are designed for a wide range of loading conditions, including loads induced by handling, transportation and installation. All construction conditions (including the prescribed backfilling steps) are taken into account, and the profiles are designed for a standard overfill range of 0.46 to 4.57 metres (1.5 to 15 feet), including AASHTO HS25 live loads.
The effect of live loads on the arch design is greatest for arches with least overfill. Larger (or smaller) overfill depths or greater live loads than those designed for with the standard BEBO® System can be accommodated for. Here, additional design calculations are carried out by BEBO® Arch International AG and extra reinforcement and/or higher concrete strengths are used where required.
Spandrel walls and wing walls normally form the ends of BEBO® System structure where overfill and embankment material needs to be retained.
Each precast spandrel wall consists of two or three segments, a centre segment, and/or two lateral segments. The spandrel wall rests on and is retained by a special “end arch element” which is provided with a curb that horizontally supports the spandrel segments. The lateral spandrel segments are additionally supported by the wing walls.
In the case of multiple span structures, special single piece lateral spandrel segments known as the “joining segments” are used.
Precast spandrel walls can be manufactured with a great variety of surface treatments or architectural finishes. As an alternative to the precast spandrel walls and wing walls, other earth retaining measures or systems such as MSE-(Mechanically Stabilized Earth, e.g. Keystone or Tensar) are also frequently used to form the ends of a BEBO® structure. The aesthetic variability of BEBO® structures is thus almost unlimited.
For the precast system, the wing wall element adjacent to the spandrel wall retain both the earth fill behind it and support the spandrel wall. This wing wall element is, however, in turn mutually supported by the spandrel wall. Additional wing wall elements serve to retain embankment fill only. The number of wing wall elements required depends on the type of arch used, the height of the spandrel wall, the slope of the embankment and the orientation of the wing wall.
Sliding or overturning of the wing wall elements is prevented by dowels, which connect them to the cast-in-place foundation slab.
Wing walls may be constructed at 90 or 120 degree orientations the spandrel wall’s longitudinal axis. Various combinations using the available wing wall arrangements are therefore possible:
Plan view of different wing wall arrangements
As with the spandrel walls, various surface treatments can be used for the precast wing walls, or MSE system wing walls can be used to provide for an almost unlimited variability of BEBO® System structures.
The simplest and most often used foundations for BEBO® System structures are cast-in-place slab type spread footings. A pedestal may be used, depending on the desired depth of bearing.
While the dimensions of the cast-in-place footings vary with the respective BEBO® System type, overfill depth and local soil conditions, the geometry of the bearing area, or “key”, is standardized. The key consists of a shallow trough into which the precast arch element is placed and subsequently filled in with grout once levelled. For structural analysis purposes, the performance of the arch/footing connection is that of a hinge.
Soil conditions may preclude the use of spread footings. In these cases, alternative foundations, such as piles, slurry walls, flat slabs or inverted arches can be used.
- BEBO® Concrete Arch System - Benefits
The BEBO System is fully pre-engineered. Its many advantageous features make it an excellent choise for applications requiring span ranges of up to 30 metres (100 feet). It offers substantial material savings in concrete and steel. As compared to traditional box culverts used currently, Bebo arches require around 30-50% less material. With material costs (such as concrete, steel, sand etc.) becoming more expensive day by day, the cost savings offered are substantial not to mention the ecological benefits.
BEBO arches are very competitive offering a substantial value proposition in terms of cost savings, low maintenance, better aesthetics, environmental benefits, faster installation periods, low labour requirements etc
- Concrete savings of up to 50% possible
- Savings in reinforcement steel of up to 40%
- Minimise the risk of construction delays caused by poor weather
- Installation according to BEBO guidelines within hours, shaving weeks off construction times
- Backfilling and compaction according to BEBO guidelines.
- No restriction for construction machinery to cross the structure once minimum overfill height is reached.
- Have a continuous joint-less pavement for overpasses (no costly bridge deck maintenance, support bearing or expansion joint repairs) thus avoiding annoying road closings
- Safety through compliance with BEBO specifications and guidelines.
- Longevity through earth overfill (cushion by means of the overfill, the effects of live load impacts)
- Much easier Maintenance.
- No approach slabs or bridge decks to deteriorate.
- Boast an excellent durability track record
- Are made from durable high quality concrete and exhibit very low life cycle costs
- Require minimal inspection
- Have low sensitivity to differential settlement (both in transverse and longitudinal direction)
- Are aesthetically pleasing and blend well with natural surroundings
- Massive savings in sand, cement, steel.
- Minimise disruption of streambeds during construction
- Minimise the environmental impact of construction activities
- Allow rivers to remain in their natural bed under the bridge
- BEBO® Concrete Arch System – Datasheets
Our Bebo datasheets are available to download below by clicking on the individual links.