repair of arch bridges
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UNIVERSITY
OF
MINHO
Daniel Oliveira & Paulo Loureno
U N I V E R S I T Y O F M I N H O
Barcelona, November 17-19 2004
REPAIR OF STONE MASONRY
ARCH BRIDGES
4TH. CONFERENCE ON ARCH BRIDGES
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INTRODUCTION
INTRODUCTION
Masonry Arch Bridges in Portugal:
- Roman Period, Medieval Age and Modern Period
(Priceless architectural and cultural legacy, but often showing
signs of damage)
Major Causes of Damage:
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Deep change of loads for which bridges were built- Lack of adequate maintenance
-Ageing processes (decay of the materials)
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INTRODUCTION
Generalized Damage:
-Absence of mortar in the stone joints
-Existence of vegetation and biological colonization
- Presence of humidity and efflorescences
-Accelerated decay of the materials
Localized Damage:- Longitudinal cracking of the arches
- Movement of abutments
- Lack of plumbness of the spandrel walls
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But damage can be minimized
- By performing periodical inspections
- By reducing the traffic load
- By carrying out repair and strengthening measures
(Preventive maintenance)
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INTRODUCTION
Principles of Intervention in the Architectural Heritage(ICOMOS):
- Minimum repair to assure safety and durability
-Respect of the original conception
- Compatibility between existing and new materials
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Survey and Repair of 2 Portuguese Masonry ArchBridges
- Boutaca Bridge
-Donim Bridge
When dealing with architectural valuable constructions
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INTRODUCTION
BOUTACA BRIDGE (stone masonry)
-Local: Batalha, center of Portugal
BOUTACABRIDGE
- Dimensions: 60m length, 7m width (5m span )
- Purpose: roadway (belonging to the former road Lisbon-Porto)
- Date of construction: 1860
T1
C6
T2
A7
C5
T3C4
T4
C3 C2
T5
C1
P7 P6
A6 A5
T6
P5 P4
A4
P3 P2
A3 A2 A1
P1
Pointed Arches
Flat roadwayTie rods + anchorages
Buttressing System
Uncertain safety conditions Survey requested4
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Results of the Survey carried out:
-Vegetation & lost of plaster (lack of maintenance)
- Humidity & biological colonization (deficient drainage system)
- Cracking in the buttress walls
-Existing anchorages much deterioratedand rather deformed (outward movement ofmasonry)
(Buttresses
overloaded)
INTRODUCTION
BOUTACABRIDGE
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Recommended Remedial Measures:
- Lightening the buttresses Tie rods + patress platesINTRODUCTION
BOUTACABRIDGE
Detail
P7
A7
C6C5
C4 C3 C2 C1
A) Structural Strengthening
Additional buttressing system
Patress plate
Tie rod6
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Waterproofing of the pavement and reconstruction of thedrainage system
INTRODUCTION
BOUTACABRIDGE
B) Other measures:
- Cleaning and removal of vegetation
- Replacement of plaster
-Need for periodical visual inspections
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DONIM BRIDGE (stone masonry)
- Local: Guimares, North of Portugal
- Dimensions: 62m length, 4m width (larger span 12m)
- Purpose: roadway (major importance untill 2 centuries ago)
- Date of construction: 15th 16th centuryINTRODUCTIONBOUTACABRIDGE
DONIM BRIDGE
A1 A2 A3 A4
Left pier
Right pier
Semicircular Arches
Flat roadway
Pier + Cutwaters
Flood arch
Precarious safety conditions Survey requested8
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Results of the Survey carried out:
- Extensive longitudinal cracking in the left arch
- Infesting vegetation all over the bridgeINTRODUCTION
BOUTACABRIDGE
DONIM BRIDGE
- Longitudinal cracking in the flood (right) arch
- Cutwater of the right pier highly damaged
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- 1 block foundation missing (underwater inspection)
INTRODUCTION
BOUTACABRIDGE
DONIM BRIDGE
-A numerical analysis (3D, non-linear) carried out allow toconfirm the damage observed and helped understandingits causes
- Spandrel walls out of plumb
(Incremental principal strains)
Major problems :
- Outward movements of spandrel walls
- Longitudinal cracking in the left and right arches
- Pre-collapse of a cutwater (right pier) 10
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INTRODUCTION
BOUTACABRIDGE
DONIM BRIDGE
Recommended Remedial Measures:
-Remove of the infill
A) Left Arch (return joints thickness to its original width)
Tie-rod
U profilesAnchor rods
ARCH
SPANDRELWALL
-Voussoirs placed in their original positions by means ofrope-strechers
- Fastening of stainless steel U profiles placed in a U shape
above the arch and close to the spandrel walls- Tie rod to bind the spandrel walls
- Infill put back into its place
] profiles
shape
tie rod
Anchorrods
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INTRODUCTION
BOUTACABRIDGE
DONIM BRIDGE
-Full width anchors across the arch
B) Flood (right) Arch (prevent further spreading of the arch)
- Stitching anchors linking the arch to the spandrel walls
Stitchinganchors
Full widthanchors
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INTRODUCTION
BOUTACABRIDGE
DONIM BRIDGE
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Dismantling and rebuilding of the right cutwater (samestones + steel cramps + steel latches)
C) Other measures:
- Replacement of the missing foundation stone block
- Waterproofing of the pavement and reconstruction of the
drainage system- Cleaning and removal of vegetation
- Repointing of the deteriorated masonry joints
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Final Remarks
- Cleaning and removal of vegetation
INTRODUCTION
BOUTACABRIDGE
DONIM BRIDGE
FINAL REMARKS
-Adoption of repair measures compatible with modernprinciples of structural intervention in the architecturalheritage
-Waterproofing and drainage of the pavement
Common features to both examples
Thank you for your attention
www.civil.uminho.pt/masonry