Arches

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Daniel Oliveira & Paulo Lourenço

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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4 T H. C O N F E R E N C E O N A R C H B R I D G E S - B A R C E L O N A , 2 0 0 4

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:

- 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


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


- …

Survey and Repair of 2 Portuguese Masonry Arch Bridges

- Boutaca Bridge- Donim Bridge

When dealing with architectural valuable constructions…

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INTRODUCTION

BOUTACA BRIDGE (stone masonry)

- Local: Batalha, center of Portugal

BOUTACA BRIDGE

- 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 requested

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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 deteriorated and rather deformed (outward movement of masonry)

(Buttresses overloaded)

INTRODUCTIONBOUTACA BRIDGE

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Recommended Remedial Measures:

- Lightening the buttresses Tie rods + patress platesINTRODUCTIO

NBOUTACA BRIDGE

Detail

P7

A6

A7

C6C5 C4 C3 C2 C1

A) Structural Strengthening

Additional “buttressing system”

Patress plate

Tie rod

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- Waterproofing of the pavement and reconstruction of the drainage system


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: Guimarães, North of Portugal

- Dimensions: 62m length, 4m width (larger span ≈ 12m)

- Purpose: roadway (major importance untill 2 centuries ago)

- Date of construction: 15th – 16th centuryINTRODUCTIONBOUTACA BRIDGE

DONIM BRIDGE

A1 A2 A3 A4

Left pier

Right pier

50 m

Semicircular Arches

Flat roadway

Pier + Cutwaters

Flood arch

Precarious safety conditions Survey requested

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Results of the Survey carried out:

- Extensive longitudinal cracking in the left arch

- Infesting vegetation all over the bridgeINTRODUCTIONBOUTACA BRIDGE

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)


DONIM BRIDGE

- A numerical analysis (3D, non-linear) carried out allow to confirm the damage observed and helped understanding its 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)

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DONIM BRIDGE

Recommended Remedial Measures:

- Remove of the infillA) Left Arch (return joint’s thickness to its original width)

Tie-rod

U profilesAnchor rods

ARCH

SP

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- Voussoirs placed in their original positions by means of rope-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

Ｕ shape

tie rod

Anchor rods

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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

Stitching anchors

Full width anchors

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DONIM BRIDGE

- Dismantling and rebuilding of the right cutwater (same stones + steel cramps + steel latches)

C) Other measures:

- Replacement of the missing foundation stone block

- Waterproofing of the pavement and reconstruction of the drainage system


- Repointing of the deteriorated masonry joints

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Final Remarks



DONIM BRIDGEFINAL REMARKS

- Adoption of repair measures compatible with modern principles of structural intervention in the architectural heritage

- Waterproofing and drainage of the pavement

Common features to both examples

Thank you for your attention

www.civil.uminho.pt/masonry

Arches

Education

minimum repair

drainage system cleaning

new materials survey

arches movement

existing anchorages

remedial measures

removal of vegetation

periodical inspections