CA2177087C - Structures prestressed by buoyancy - Google Patents
Structures prestressed by buoyancy Download PDFInfo
- Publication number
- CA2177087C CA2177087C CA 2177087 CA2177087A CA2177087C CA 2177087 C CA2177087 C CA 2177087C CA 2177087 CA2177087 CA 2177087 CA 2177087 A CA2177087 A CA 2177087A CA 2177087 C CA2177087 C CA 2177087C
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- CA
- Canada
- Prior art keywords
- buoyancy
- superstructure
- bridge structure
- bridge
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D15/00—Movable or portable bridges; Floating bridges
- E01D15/14—Floating bridges, e.g. pontoon bridges
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Bridges Or Land Bridges (AREA)
- Foundations (AREA)
Abstract
This invention comprises the use of the force of buoyancy to counter the gravity forces due to the dead and live loads imposed on bridge structures spanning bodies of water.
This is achieved by securing to the underside of the bottom chord or element of the bridge superstructure, restrained at each end from vertical movement, a buoyancy block or a plurality of buoyancy blocks submerged at all levels of the body of water, thus providing the desired prestress to the superstructure to counter the gravity loads.
Further, in a trussed type of superstructure, buoyancy collars may be secured to the vertical elements of the truss, providing additional prestressing forces when the body of water rises and a resistance to the deflection of the bridge structure from the live loads, thus reducing the shearing forces, bending moments, and reactions at the two ends or abutments of the bridge.
This is achieved by securing to the underside of the bottom chord or element of the bridge superstructure, restrained at each end from vertical movement, a buoyancy block or a plurality of buoyancy blocks submerged at all levels of the body of water, thus providing the desired prestress to the superstructure to counter the gravity loads.
Further, in a trussed type of superstructure, buoyancy collars may be secured to the vertical elements of the truss, providing additional prestressing forces when the body of water rises and a resistance to the deflection of the bridge structure from the live loads, thus reducing the shearing forces, bending moments, and reactions at the two ends or abutments of the bridge.
Description
_2177087 SPECIFICATION
STRUCTURES PRESTRESSED BY BUOYANCY
Background of the Invention:
( 1 ) Field of Invention:
Civil/Structural Engineering relating to Bridges spanning bodies of water.
STRUCTURES PRESTRESSED BY BUOYANCY
Background of the Invention:
( 1 ) Field of Invention:
Civil/Structural Engineering relating to Bridges spanning bodies of water.
(2) Description of the Prior Art:
(a) Floating Bridges, with or without intermediate pontoons the decks of which fluctuate with the surface level of the body of water spanned.
While employing the basic concept of the principle of buoyancy, the disadvantage is the fluctuating deck level with associated problems at the bridge ends, as well as"
stability of the bridge alignment.
Examples of prior art in these concepts are shown in the Hill [U.S. Patent No. 2,085,156], Haakonsen [U.S. Patent No. 5,216,773], Odot [French Patent No. 805,289], Gehlen [German Patent No. 1,035,679], also known as "Fahrbaren"
which is identical to Gillois/Gehlen [U.S. Patent No.
(a) Floating Bridges, with or without intermediate pontoons the decks of which fluctuate with the surface level of the body of water spanned.
While employing the basic concept of the principle of buoyancy, the disadvantage is the fluctuating deck level with associated problems at the bridge ends, as well as"
stability of the bridge alignment.
Examples of prior art in these concepts are shown in the Hill [U.S. Patent No. 2,085,156], Haakonsen [U.S. Patent No. 5,216,773], Odot [French Patent No. 805,289], Gehlen [German Patent No. 1,035,679], also known as "Fahrbaren"
which is identical to Gillois/Gehlen [U.S. Patent No.
3,021,544], Tourchette [U.S. Patent No. 1,934,286], Williams [U.S. Patent No. 716,160], and Caroni [U.S. Patent No. 1,640,980].
I
~_2~ ~~~8~
(b) Bridges fixed at the ends, as in the Applicant's Concept, but utilizing the buoyancy concept in a limited way; i.e., providing intermediate supports by means of separate structures with buoyancy blocks attached to them and to the bottom chord of the superstructure.
These concepts, such as described in the Main [Great Britain Patent No. 354,219], Hodgson [Great Britain Patent No.
3,734] and Tosowes [Great Britain Patent No. 4,145] all have several disadvantages and/or problems related to them, viz:
[i] the need for discontinuity in the superstructure, otherwise differential settlements or fluctuations in support levels will cause unpredictable changes in shears, bending moments and support reactions;
[ii] the need for the construction and pre-placement of the intermadiate support structures containing the buoyancy blocks, prior to the placement of the bridge superstructure onto the said supports;
[iii] stability of the intermediate supports, especially when currents are present in the body of water spanned;
[iv] Difficulties with installation of the superstructure, in sections, over the body of water.
.2177p87 All the above problems are solved by the Applicant's Concept of constructing the entire bridge - with the option of leaving out the bridge deck, if necessary for stability of the structure during flotation and towing to the bridge site - in a dry dock as close as practicable to the bridge site, followed by its lowering, placement upon abutments at each end of the bridge, and securing thereto.
The deck may be either prefabricated or cast-in-situ, and secured onto the top chord of the superstructure.
Summary of the Invention:
The subject invention comprises the prefabrication of a bridge superstructure, spanning a body of water, consisting of the following components which form the integral part of the bridge:
1. A buoyancy block of a length equal to the length of the bottom chord of a bridge truss, cast-in-situ or laid out in one or more prefabricated buoyancy elements butted together along the full length of the bottom chord of a bridge truss.
2177p8~
2. A superstructure made up of trusses, cast-in-situ or assembled from prefabricated elements, secured to the buoyancy block; the distance between the top chord and the bottom chord of the trusses being such as will result in the top chord being above High Water Level of the body of water to be spanned, and the bottom chord being below the Low Water Level of the body of water. Buoyancy collars are then secured to the vertical members of the trusses, at an elevation such that their soffits are at low water level when the bridge is in its final position.
3. A roadway deck being either cast-in-situ or composed of a plurality of prefabricated deck elements butted together and secured to the top chord of the trusses.
Components 1 and 2 are built or assembled [if in prefabricated elements] in a dry-dock and towed to the bridge site for placement upon abutments at each end of the bridge. Component 3 may be cast-in-situ, but is preferably placed upon the top chord of the superstructure in prefabricated elements from each end of the bridge to balance the lowering of the superstructure onto the abutments.
y .2177p87 The buoyancy block, the trusses and the collars secured thereto, are towed from the dry-dock to the final bridge alignment, with care being taken that the metacenter of the structure towed is above the center of gravity of the structure towed.
After placement of the superstructure without the deck, onto the final bridge location, the deck is either cast-in-situ or secured to the top of the trusses from each end of the bridge, to balance the process of lowering the complete structure onto the abutments, and securing it thereto.
e.
Brief Description of the Drawings:
Figures 1 and 4 are side views of the embodiment of the ir_vention;
Figure lA and 4A are cross-sectional views related to Figures 1 and 4;
Figure 2 is a detail of the buoyancy block 4 shown in Figure 1;
Figure 3 is a detail of the buoyancy block 13 shown in Figure 4;
wherein:
H W is the High Water Level L.W.L. is the Low Water Level 1 is an abutment _2 is the roadway deck is a truss supporting the roadway deck _2, the bottom chord of the truss being secured to a buoyancy block 4_, which is submerfied at Low Water Level, and may be in one or more pieces butted together along the entire underside of the bottom chord of the truss; the buoyancy block may be secured to the truss by rieans of embedded metal ~, or by any other means.
I
~_2~ ~~~8~
(b) Bridges fixed at the ends, as in the Applicant's Concept, but utilizing the buoyancy concept in a limited way; i.e., providing intermediate supports by means of separate structures with buoyancy blocks attached to them and to the bottom chord of the superstructure.
These concepts, such as described in the Main [Great Britain Patent No. 354,219], Hodgson [Great Britain Patent No.
3,734] and Tosowes [Great Britain Patent No. 4,145] all have several disadvantages and/or problems related to them, viz:
[i] the need for discontinuity in the superstructure, otherwise differential settlements or fluctuations in support levels will cause unpredictable changes in shears, bending moments and support reactions;
[ii] the need for the construction and pre-placement of the intermadiate support structures containing the buoyancy blocks, prior to the placement of the bridge superstructure onto the said supports;
[iii] stability of the intermediate supports, especially when currents are present in the body of water spanned;
[iv] Difficulties with installation of the superstructure, in sections, over the body of water.
.2177p87 All the above problems are solved by the Applicant's Concept of constructing the entire bridge - with the option of leaving out the bridge deck, if necessary for stability of the structure during flotation and towing to the bridge site - in a dry dock as close as practicable to the bridge site, followed by its lowering, placement upon abutments at each end of the bridge, and securing thereto.
The deck may be either prefabricated or cast-in-situ, and secured onto the top chord of the superstructure.
Summary of the Invention:
The subject invention comprises the prefabrication of a bridge superstructure, spanning a body of water, consisting of the following components which form the integral part of the bridge:
1. A buoyancy block of a length equal to the length of the bottom chord of a bridge truss, cast-in-situ or laid out in one or more prefabricated buoyancy elements butted together along the full length of the bottom chord of a bridge truss.
2177p8~
2. A superstructure made up of trusses, cast-in-situ or assembled from prefabricated elements, secured to the buoyancy block; the distance between the top chord and the bottom chord of the trusses being such as will result in the top chord being above High Water Level of the body of water to be spanned, and the bottom chord being below the Low Water Level of the body of water. Buoyancy collars are then secured to the vertical members of the trusses, at an elevation such that their soffits are at low water level when the bridge is in its final position.
3. A roadway deck being either cast-in-situ or composed of a plurality of prefabricated deck elements butted together and secured to the top chord of the trusses.
Components 1 and 2 are built or assembled [if in prefabricated elements] in a dry-dock and towed to the bridge site for placement upon abutments at each end of the bridge. Component 3 may be cast-in-situ, but is preferably placed upon the top chord of the superstructure in prefabricated elements from each end of the bridge to balance the lowering of the superstructure onto the abutments.
y .2177p87 The buoyancy block, the trusses and the collars secured thereto, are towed from the dry-dock to the final bridge alignment, with care being taken that the metacenter of the structure towed is above the center of gravity of the structure towed.
After placement of the superstructure without the deck, onto the final bridge location, the deck is either cast-in-situ or secured to the top of the trusses from each end of the bridge, to balance the process of lowering the complete structure onto the abutments, and securing it thereto.
e.
Brief Description of the Drawings:
Figures 1 and 4 are side views of the embodiment of the ir_vention;
Figure lA and 4A are cross-sectional views related to Figures 1 and 4;
Figure 2 is a detail of the buoyancy block 4 shown in Figure 1;
Figure 3 is a detail of the buoyancy block 13 shown in Figure 4;
wherein:
H W is the High Water Level L.W.L. is the Low Water Level 1 is an abutment _2 is the roadway deck is a truss supporting the roadway deck _2, the bottom chord of the truss being secured to a buoyancy block 4_, which is submerfied at Low Water Level, and may be in one or more pieces butted together along the entire underside of the bottom chord of the truss; the buoyancy block may be secured to the truss by rieans of embedded metal ~, or by any other means.
4. is the buoyancy block, made up of a reinforces: concrete shell Z
containing buoyant material $, such as STYRC~,~OI~; as shoran in figure 2; alternatively, it may be a steel shell ~ containing buoyant material $, as shown in figure 3.
are metal elements embedded in the buoyancy block 4 are optional joints between buoyancy block elements 7 is the reinforced concrete shell containing the buoyant material $
$ is the buoyancy material, such as STYROPOR, contained within the buoyancy block 4 Q is the steel, or metal shell, containing the buoyant material $
1Q is the roadway deck 1~ is an abutment 12 is a VIERENDEEL type truss ~3 is a buoyancy block as described in 4 14 are optional joints of the buoyancy block ~
1~ is a buoyancy collar, secured to the vertical elements of a VIERENDEEL truss, with the soffit at Low Water Level.
~~.scription of the Preferred Embodiments:
'The Best Mode for Carrying Out the Invention is as fellows:
Excavate a "dry-dock° adjacent to the bride,e site;
Prepare the base of the dry-dock to receive buoyancy 'olocks which are placed upon the dry-dock bed;
Placc the buoysncy blocks upon the dry-dock bed;
Secure prefabricated truss elements of the bride to tl~e buoyancy blocks;
Complete assesbly of the prefabricated bridge truss, including, all bracing Secure buoyancy collars to the vertical members of the truss, preferzbly of the VIERENDEEL type;
Introduce water into dry-dock;
Tow the truss-buoyancy block, buoyancy collar assembay to bri~!~n site;
Lower the asser.:bly onto abutments by means of, preferahly, t'~~
placement of prefabricated bride deck units auto the top cho-d of the truss, evenly fro.~.i each abutment;
Alternatively, cc.~~ibine the above described method of lowerir~
the bride onto tae abutments by flotidin~ selected buoyancy chambers within the buoyancy block Secure the entire: bridfie assembly onto the abutments.
containing buoyant material $, such as STYRC~,~OI~; as shoran in figure 2; alternatively, it may be a steel shell ~ containing buoyant material $, as shown in figure 3.
are metal elements embedded in the buoyancy block 4 are optional joints between buoyancy block elements 7 is the reinforced concrete shell containing the buoyant material $
$ is the buoyancy material, such as STYROPOR, contained within the buoyancy block 4 Q is the steel, or metal shell, containing the buoyant material $
1Q is the roadway deck 1~ is an abutment 12 is a VIERENDEEL type truss ~3 is a buoyancy block as described in 4 14 are optional joints of the buoyancy block ~
1~ is a buoyancy collar, secured to the vertical elements of a VIERENDEEL truss, with the soffit at Low Water Level.
~~.scription of the Preferred Embodiments:
'The Best Mode for Carrying Out the Invention is as fellows:
Excavate a "dry-dock° adjacent to the bride,e site;
Prepare the base of the dry-dock to receive buoyancy 'olocks which are placed upon the dry-dock bed;
Placc the buoysncy blocks upon the dry-dock bed;
Secure prefabricated truss elements of the bride to tl~e buoyancy blocks;
Complete assesbly of the prefabricated bridge truss, including, all bracing Secure buoyancy collars to the vertical members of the truss, preferzbly of the VIERENDEEL type;
Introduce water into dry-dock;
Tow the truss-buoyancy block, buoyancy collar assembay to bri~!~n site;
Lower the asser.:bly onto abutments by means of, preferahly, t'~~
placement of prefabricated bride deck units auto the top cho-d of the truss, evenly fro.~.i each abutment;
Alternatively, cc.~~ibine the above described method of lowerir~
the bride onto tae abutments by flotidin~ selected buoyancy chambers within the buoyancy block Secure the entire: bridfie assembly onto the abutments.
Claims (5)
1. A bridge structure, spanning a body of water, restrained at each of its two end supports from vertical movement, comprising:
a trussed girder comprising a top chord and a bottom chord, connected by an open web system of structural elements between the top and bottom chords; wherein the top chord supports a roadway and to the underside of the bottom chord of which is fixed, along its full length, a buoyancy support, submerged below the lowest surface level of the body of water spanned, thus providing an upward prestressing force countering the dead and live loads of the superstructure, including the roadway.
a trussed girder comprising a top chord and a bottom chord, connected by an open web system of structural elements between the top and bottom chords; wherein the top chord supports a roadway and to the underside of the bottom chord of which is fixed, along its full length, a buoyancy support, submerged below the lowest surface level of the body of water spanned, thus providing an upward prestressing force countering the dead and live loads of the superstructure, including the roadway.
2. The bridge structure as defined in Claim 1, wherein the buoyancy support comprises a continuous buoyancy block.
3. The bridge structure as defined in Claim 1, wherein the buoyancy support comprises a plurality of buoyancy blocks butted together.
4. The bridge structure as defined in Claims 1, 2 or 3, wherein the open-web system of structural elements includes vertical members, to which are secured buoyancy collars, the lower ends of which are located as close to the lowest water surface elevation as practicable; said collars providing a further counter-force to the dead load of the superstructure when the water level rises, as well as providing a counter-force to the live loads imposed on the roadway deck by resisting the deflection of the bridge structure by the buoyanct forces provided by said collars, thus reducing the shearing forces and bending moments to which the superstructure is subjected, as well as reducing the reactions at the two end supports.
5. A method of erecting a bridge structure, comprising the steps of prefabricating and assembling the bridge structure as defined in Claims 1, 2, 3 or 4, in a dry dock, floating the assembled structure to a predetermined location and placing the said structure on two end supports which have been previously provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2177087 CA2177087C (en) | 1996-05-22 | 1996-05-22 | Structures prestressed by buoyancy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2177087 CA2177087C (en) | 1996-05-22 | 1996-05-22 | Structures prestressed by buoyancy |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2177087A1 CA2177087A1 (en) | 1997-11-23 |
| CA2177087C true CA2177087C (en) | 2000-04-25 |
Family
ID=4158240
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2177087 Expired - Fee Related CA2177087C (en) | 1996-05-22 | 1996-05-22 | Structures prestressed by buoyancy |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2177087C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110184895B (en) * | 2019-07-01 | 2023-10-27 | 沈阳建筑大学 | Bridge capable of automatically adjusting height along with rising of river water level and construction method thereof |
| CN112281847A (en) * | 2020-11-03 | 2021-01-29 | 浙江省围海建设集团股份有限公司 | Mould bag concrete construction system and method |
| CN112663477B (en) * | 2020-12-18 | 2021-10-22 | 保利长大工程有限公司 | Big net empty heavy load liftable navigation hole landing stage in typhoon high-rise district |
-
1996
- 1996-05-22 CA CA 2177087 patent/CA2177087C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2177087A1 (en) | 1997-11-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |