WO2021180691A1

WO2021180691A1 - An arch bridge

Info

Publication number: WO2021180691A1
Application number: PCT/EP2021/055872
Authority: WO
Inventors: Stian Schjelderup; Øystein Trondahl
Original assignee: Schjelderup Trondahl Arkitekter As
Priority date: 2020-03-09
Filing date: 2021-03-09
Publication date: 2021-09-16
Also published as: NO20200282A1; EP4118266A1; NO345692B1

Abstract

An arch bridge comprising a bridge deck for providing a walking/driving surface. The bridge deck is supported by a first arch and a second arch both concave downward, and each comprising a top point which if defined by a highest point of the arch viewed in a vertical plane. An intermediate deck is arranged between the first and second arch and connected at a location below the top point of respective arches such that the intermediate deck is lowered between the top points. The bridge deck is provided by the intermediate deck and a section of the arches located above the location and including the top point, so that the bridge deck of the arch bridge is elevated at the top points.

Description

AN ARCH BRIDGE

The invention is directed to an arch bridge comprising a bridge deck for providing a walking/driving surface. The arch bridge comprises a first arch and a second arch, the arches are connected by an intermediate deck which is lowered in relation to the top point of the first and second arches, the intermediate deck together with the first and second arch provides a bridge deck with elevated sections at the top points.

An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it.

An arch bridge is a bridge shaped as a curved arch and with abutments at each end. The abutment is a structure built so support the lateral pressure of an arch or span, e.g. at the ends of a bridge.

Arch bridges work by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side. A viaduct (a long bridge) may be made from a series of arches, although other more economical structures are typically used today.

An arch is a pure compression form and it can span a large area by resolving forces into compressive stresses and, in turn eliminating tensile stresses. This is sometimes referred to as arch action. As the forces in the arch are carried to the ground, the arch will push outward at the base, called thrust. As the rise, or height of the arch decreases, the outward thrust increases. In order to maintain arch action and prevent the arch from collapsing, the thrust needs to be restrained, either with internal ties or external bracing, such as abutments.

The most common true arch configurations are the fixed arch, the two-hinged arch, and the three-hinged arch. See figure 1 A-C.

The fixed arch (fig 1C) is most often used in reinforced concrete bridge and tunnel construction, where the spans are short. Because it is subject to additional internal stress caused by thermal expansion and contraction, this type of arch is considered to be statically indeterminate.

The two-hinged arch (fig IB) is most often used to bridge long spans. This type of arch has pinned connections at the base. Unlike the fixed arch, the pinned base is able to rotate, allowing the structure to move freely and compensate for the thermal expansion and contraction caused by changes in outdoor temperature. However, this can result in additional stresses, so that the two-hinged arch is also statically indeterminate, although not to the degree of the fixed arch. The three-hinged arch (fig 1 A) is not only hinged at its base, like the two-hinged arch, but at the mid-span as well. The additional connection at the mid-span allows the three-hinged arch to move in two opposite directions and compensate for any expansion and contraction. This type of arch is thus not subject to additional stress caused by thermal change. The three-hinged arch is therefore said to be statically determinate. It is most often used for medium-span structures, such as large building roofs. Another advantage of the three-hinged arch is that the pinned bases are more easily developed than fixed ones, allowing for shallow, bearing-type foundations in medium-span structures. In the three-hinged arch, "thermal expansion and contraction of the arch will cause vertical movements at the peak pin joint but will have no appreciable effect on the bases," further simplifying the foundation design.

Arches have many forms, but all fall into three basic categories: circular, pointed, and parabolic. Arches can also be configured to produce vaults and arcades.

Pointed arches were most often used by builders of Gothic-style architecture. The advantage to using a pointed arch, rather than a circular one, is that the arch action produces less horizontal thrust at the base. This innovation allowed for taller and more closely spaced openings, typical of Gothic architecture.

Arches with a circular form, also referred to as rounded arches, were commonly employed by the builders of ancient, heavy masonry arches. Ancient Roman builders relied heavily on the rounded arch to span large, open areas. Several rounded arches placed in-line, end-to-end, form an arcade.

Vaults are essentially "adjacent arches that are assembled side by side". If vaults intersect, complex forms are produced with the intersections. The forms, along with the strongly expressed ribs at the vault intersections, were dominant architectural features of Gothic cathedrals.

The parabolic arch employs the principle that when weight is uniformly applied to an arch, the internal compression resulting from that weight will follow a parabolic profile. Of all arch types, the parabolic arch produces the most thrust at the base but can span the largest areas. It is commonly used in bridge design, where long spans are needed.

It is an object of the present invention to provide an arch bridge than have large span or at least larger than traditional span and having decreasing rise, or height of the arch. It is another object of the present invention to provide a bridge that has esthetic appearance by having simple construction and using less materials. SUMMARY OF THE INVENTION

The invention is directed to an arch bridge comprising a bridge deck for providing a walking or driving surface for pedestrians and/or other means of transportation. The bridge comprises a first arch and a second arch both concave downwards, with its ends pointing downwards, and each comprising a top point which if defined by a highest point of the arch viewed in a vertical plane of the arch bridge.

The top point may also be referred to as the point located highest of the rise, or the height of respective first and second arch. The term “concave downward” is when the slope of the curve decreases. It is also called “Concave” or “Convex upward”. May also be referred to as a “standing arch”.

The term “concave upwards” is when the slope of the curve increases. It is also called “Convex” or “Convex downward”. May also be referred to as a “hanging arch”.

Each arch is a vertical curved structure that spans an elevated space and may or may not comprise a peak. The arch may be a curve having the highest point at one end and curved downward to either side, or the arch may comprise a peak situated between the ends of the arches and which peak also defines the top point of the arch.

The first and second arch may also be referred to as the main arches of the bridge.

An intermediate deck is arranged between the first and second arch and connected at a location below the top point of respective arches so that the intermediate deck is lowered between the top points of the first and second arch. The section of the main arch situated above the point of connection of the intermediate deck and including the top point, may be referred to as the top section of the main arch.

The ends of the intermediate deck may be shaped and adapted to the shape of the first and second arch. The ends of the intermediate deck may be adapted to fit into a recess provided on the curved arch and/or it may be cut in angle to following the shape of the arch curve. The interconnection between the main arch and the intermediate deck may be mechanically connected and rigid. The bridge deck is provided by the intermediate deck and a section of the arches located above the location and including the top point (top section of the main arch), such that the bridge deck or the surface of the bridge deck is elevated at the top sections across the bridge. Thus, the intermediate deck and the top section of the main arches constitutes the bridge deck. The bridge deck may also be referred to as a carriageway, pathway and/or road way of the bridge. The bridge deck of the present invention is provided with elevated sections located at the top section of the main arches. The bridge deck, pathway or carriageway may also comprise additional supports for the pedestrians or drivers. The additional support may be a board, plates, wooden structures, metal structures, reinforced concrete, asphalt, etc. provided above the intermediate deck and the top section of the first and second arches. The arch bridge is a bridge comprising at least one arch-shaped (curved arch or span) and with abutments at each end. The abutments being a structure to support the lateral pressure of the arch (or span).

The arch bridge of the present invention comprises at least two arches (first and second arches). The term “arch” may also be directed to a “complete arch” a section of an arch or a “half arch”.

The first and second arches are connected by an intermediate deck arranged in a lowered vertical orientation relative to the top points of the first and second arches.

The intermediate deck may be a straight horizontal deck, or the intermediate deck may be a curved deck. Preferably, the intermediate deck is a curved deck and may also be referred to as the secondary arch. The intermediate deck (secondary arch) may be a third arch with ends curved

(pointing) upwards (“u-shaped”) and arranged in an opposite direction to the first and second arch, such as to provide a wave-shaped bridge deck. Where the top point of the first and second arches defines the uppermost (top) point of the bridge deck, while the bottom point of the third arch defines the lowermost point of the bridge deck. Each of the first, second and third arch may be at least one of a; parabolic arch, elliptical arch, horseshoe arch, round arch, segmental arch and unequal round arch.

The first, second and third arches may be segmental circular arches, and wherein a radius of the first and second arch (r) is smaller than a radius of the third arch (R).

The arch bridge construction of the present invention is based on mutually interacting of push and pull forces between the first, second arch and the third arch. Thus, the interaction between the main arches and the secondary arche. The main arch may be partly stiffer because of the long interconnection with the secondary arch.

It is known that an arch bridge works by transferring the weight of the bridge and its loads partially into a horizontal thrust restrained by the abutments at either side. As the rise, or height of the arch decreases, the outward thrust increases.

In order to maintain arch action and prevent the arch from collapsing, the thrust needs to be restrained, either with internal ties or external bracing, such as abutments.

According to the present invention, the intermediate deck (secondary arch) is arranged between two adjacent arches such that the vertical force acting on the intermediate deck is transferred horizontally to the upper section of the arches (in additional to vertically to the ends of the arches).

The shape of the intermediate deck allows for a calculated weight distribution. By allowing the intermediate deck to be a secondary arch curved in an opposite direction of the two adjacent main arches, provides a thrust that sustains the shape of the two arches. Thus, avoiding the main arches from “collapsing”, when the weight of the bridge and its loads acts vertically to the secondary arch. Thus, the outward thrust to the abutments are restrained since the shape of the main arches are sustained.

The arch bridge of the present invention is based on mutually interacting constructions between push and pull forces through the system reducing mass and secondary constructions such as additional supports. The main arch (first and second arches) is dependent on the secondary arch (intermediate deck) and their binding properties. A slim secondary arch benefits from the torque stiff connection at its connection point.

The interconnection between the main arch and the secondary is mechanically connected and rigid. The combination between the length of the main arc, the secondary arch and the connecting surface area is crucial for its design appearance and slim dimensions.

The first and the second arch may further be connected to each other at one end, below the intermediate deck, and wherein the one end is supported by a pillar.

The arch bridge may comprise a plurality of first and second aches arranged alternating and connected to each other by the intermediate deck.

The invention is not limited to arch bridges made from wood but is exemplified with it. The same principle of the bridge applies for different materials, like steel, aluminium, composites etc. Thus, the bridge of the present invention may be made of any materials such as wood, steel, aluminium, composites or a combination thereof.

The bridge is scalable and may be adaptable to a variety of different applications over land and water. Specific parameter-range for each material is the basis for an algorithm which represents the scalability of the construction. The parameters are always in a certain relation to each other to achieve the paramount design.

The two main construction parts; the main “standing” arches and the secondary “hanging” intermediate arches, are dependent on each other through the mechanical and rigid interconnection to achieve their full potential. Neither of the two can achieve the full strength independently. The midpoint of the intermediate arch may preferably be lower than the highest point of the main arches if dimensions should be equal on both arcs and not overload the main arch at its weakest part.

Two halves of the main “standing” arches together with one secondary “hanging” intermediate arch is the minimum application to fulfil the purpose of the construction.

The description above, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of the preferred embodiment which should be read in conjunction with the accompanying drawings in which:

Figs. 1 A-C shows prior art bridges an arch span

Figs. 2 A-B shows a bridge with an arch span with an overlying bridge deck (2A) and an intermediate bridge deck (2B) Figs. 3 A-C shows a bridge with an arch span with an underlying bridge deck (3 A and 3C and a self-anchored bridge (3B).

Figs. 4 A-C shows arch bridges comprises two or more arches and where the bridge deck is arranged on top of the arches.

Figs. 5 A-C shows an arch bridge comprising a first and second arch and an intermediate deck connecting the first and second arches. Figs. 6 A-B shows the first, second and third arch, each defining a segment of a circle having radius (R,r).

Fig 7 shows in 3-D the arch bridge according to an embodiment of the present invention.

Fig. 8 shows an arch bridge comprising a fence provided along the bridge deck.

DETAILED DESCRIPTION OF THE DRAWINGS

The bridge of the present invention is an interacting construction reducing both height and mass, increasing span lengths, and at the same time eliminating traditionally used secondary construction (supports) in regular arch bridge structures (both dimensions and struts/columns).

The traditional arch bridge principles usually comprise of 3 main parts: The carriageway, the arch and the interconnections between the two comprising of rods or wires (hanging)/columns or plates (standing) transferring load to its foundations. Some known principles are interacting constructions, but usually dependent on all three main parts in some sort.

The fixed arch (fig 1C) is most often used in reinforced concrete bridge and tunnel construction, where the spans are short. Because it is subject to additional internal stress caused by thermal expansion and contraction, this type of arch is considered to be statically indeterminate. The two-hinged arch (fig IB) is most often used to bridge long spans. This type of arch has pinned connections at the base. Unlike the fixed arch, the pinned base is able to rotate, allowing the structure to move freely and compensate for the thermal expansion and contraction caused by changes in outdoor temperature. However, this can result in additional stresses, so that the two-hinged arch is also statically indeterminate, although not to the degree of the fixed arch.

The three-hinged arch (fig 1 A) is not only hinged at its base, like the two-hinged arch, but at the mid-span as well. The additional connection at the mid-span allows the three-hinged arch to move in two opposite directions and compensate for any expansion and contraction. This type of arch is thus not subject to additional stress caused by thermal change. The three-hinged arch is therefore said to be statically determinate.

The arch bridges are traditionally provided with a bridge deck on three different levels. On top of the arch as shown in figure 2 A, intermediate level and crossing the arch in figure 2B, and below the arch, in figure 3 A-C. From the bridge deck, the loads are transferred to the arch by columns or wires or a combination thereof.

Figure 4 A-C shows traditionally arch bridges comprising one or more main arches. The bridge deck is arranged on top of each arch such that the arch is fully supporting the entire bridge deck. The arches are connected by an intermediate deck extending from one top point of arch to another. If the greater span of each arch, the rise or height of the arch will be higher, making the length each intermediate deck longer. The long and unsupported intermediate deck need to be supported by columns extending form the intermediate deck to the arch curvature.

The present invention, allows the removal of the supporting columns by providing an intermediate deck 15,16 which is lowered in relation to the top points of the main arches 12,13. The intermediate deck 15,16 and the top section of each main arches 12,13 constitutes the bridge deck 11 such that the bridge deck 11 will have an slightly wave-like structure.

Figure 5 A discloses an embodiment of an arch bridge 10 according to the present invention. The arch bridge 10 comprising a bridge deck 11 for providing a walking or driving surface for pedestrians and/or automobiles.

The arch bridge 10 comprises a first arch 12 and a second arch 13 both having an end curved downward from a top point defined as the vertically highest point of the arch. The arch 12,13 may also have a peak defining the top point of the arch as shown in figure 5 C. The first and the second arches 12,13 may also be referred to as main arches, each comprises a top point 14 which if defined by a highest point of the arch 12,13 viewed in a vertical plane.

The arch bridge 10 further comprises an intermediate deck 15 arranged between the first and second arch 12,13 and connecting the first and second arches 12,13.

The intermediated deck is connected to respective first and second arches 12,13 at a location below the top point 14 of respective arches 12,13 such that the intermediate deck 15 is lowered between the top points 14. The section of the arch located above the connection point may be referred to as the top section of the arch 12,13.

The bridge deck 11 is provided by the intermediate deck 15 and the top section of the arches 12,13, so that the bridge deck 11 of the arch bridge 10 is elevated at the top sections of the arches 12,13.

The intermediate deck 15 may be a third arch 16 with its ends pointing upwards (concave upwards), thus curved in an opposite direction to the first and second arch 12,13, such as to provide a wave-shaped bridge deck 15.

Each of the first, second and third arch 12,13,16 may be at least one of a; parabolic arch, elliptical arch, horseshoe arch, round arch, segmental arch and unequal round arch, or a combination thereof.

Preferably, the first, second and third arches 12,13,16 may be segmental circular arches, and wherein a radius of the first and second arch (r) is smaller than a radius of the third arch (R). This is shown in figure 6 A and 6B, where the radius provided by the intermediate arch, defines a circle which is much larger than the radius of the circle provided by the main arches 12,13.

Figure 7 shows that each main arch 12,13 may comprise a plurality of sub-arches arranged adjacent and side by side. Accordingly, each sub-arch may be provided by an intermediate deck 15,16 according to the invention. Figure 7 also shows the additional support, i.e. plates that are arranged on top of the structure such that it constitutes the bridge deck 11.

The first and the second arch 12,13 may be connected to each other at an abutment, below the intermediate deck 15, and wherein the abutment may be supported by a pillar 17.

The arch bridge 0 of the present invention, may comprise a plurality of first and second arches 12,13 arranged alternating and connected to each other by one or more intermediate decks 15. The arch bridge 10 of the present invention has two major distinguishing features compared to traditional arch bridges.

The bridge deck is located on top of the arch and is lowered down in between the arches. The effect is a slight wave-like curvature of the bridge deck, and the lowered span (intermediate deck) provided between the main arches 12,13 is relatively short, since it is located at a location on the arches closer to each other and allows for the removal of the columns or wires supporting the bridge deck.

The arch bridge of the present invention comprises main arches 12,13 and intermediate arches 15,16 connecting the main arches 12,13. Static principles comprises interaction between standing main arches 12,13 from foundation to foundation with intermediate hanging arches 15,16 between the two main arches 12,13. The main arches 12,13 may span full length (same height to same height) or span halfway. The intermediate arch 15,16 will always have to combine two half main arches 12,13, one full and one half main arches or two full arches. The principle allows a slimmer and simpler construction with less materials than the known principles.

The design is also suited for urban use or situations where there are universal design requirements (wheel chair etc.) are present.

The Interacting construction is scalable. Its dimensions are proportional when scaled until the limit of each typical load condition with a certain factor. The factor decides the arch dimensions and the connecting properties.

The construction method allows a great deal of modulization and effective production. The construction may easily be adapted to site and transportation specific preconditions. Depending on the element size, the construction method may be customized for easy assembly on site with few components. The arch bridge requires solid foundations specific for each site. The resultant forces are predictable as soon as the dimensions and materials are selected. The method may also be easily demountable and may be suited for temporary installations.

The bridge of the present invention, may also be built with less materials than the typical bridge constructions. If built from wood, the C02 footprint is almost zero and environmentally friendly. It is also renewable and recyclable.

Claims

1. An arch bridge (10) comprising a bridge deck (11) for providing a walking or driving surface for pedestrians and/or automobiles, the arch bridge (10) comprises a first arch (12) and a second arch (13) both concave downwards, and each comprising a top point (14) which if defined by a highest point of the arch (12,13) viewed in a vertical plane of the arch bridge, characterized in that the arch bridge (10) further comprises an intermediate deck (15) arranged between the first and second arch (12,13) and connected at a location below the top point (14) of respective arches (12,13) such that the intermediate deck (15) is lowered between the top points (14), wherein the bridge deck (11) is provided by the intermediate deck (15) and a section of the arches (12,13) located above the location and including the top point (14), so that the bridge deck (11) of the arch bridge (10) is elevated at the top points (14).

2. The arch bridge (10) according to claim 1, wherein the intermediate deck (15) is a third arch (16) concave upwards, in an opposite direction to the first and second arch (12,13), such as to provide a wave-shaped bridge deck (11).

3. The arch bridge (10) according to claim 2, wherein each of the first, second and third arch (12,13,16) are at least one of a; parabolic arch, elliptical arch, horseshoe arch, round arch, segmental arch and unequal round arch.

4. The arch bridge (10) according to claim 3, wherein the first, second and third arches (12,13,16) are segmental circular arches, and wherein a radius of the first and second arch (r) is smaller than a radius of the third arch (R).

5. The arch bridge (10) according to any one of the preceding claims, wherein the first and the second arch (12,13) are connected to each other at an abutment below the intermediate deck (15), and wherein the abutment is supported by a pillar (17).

6. The arch bridge (10) according to any one of the preceding claims, wherein the arch bridge comprises a plurality of first and second arches (12,13) arranged alternating and connected to each other by the intermediate deck (15).