The document discusses the repair of two historic masonry arch bridges in Portugal: the Boutaca Bridge and the Donim Bridge. Surveys found that both bridges showed signs of deterioration and structural issues like cracking, outward movement of walls, and damaged cutwaters. For each bridge, the document outlines targeted repair measures including adding structural reinforcement with tie rods and anchors, repairing arches, rebuilding damaged sections, and improving drainage to address the issues found and strengthen the bridges while respecting their historic nature.

1. 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

2. 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 (P riceless 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)

3. INTRODUCTION 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 (Preventive maintenance) 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…

4. INTRODUCTION 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 When dealing with architectural valuable constructions … 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

5. 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 BOUTACA BRIDGE BOUTACA BRIDGE (stone masonry)  - Local: Batalha, center of Portugal - Dimensions: 60m length, 7m width (5m span ) - Purpose: roadway (belonging to the former road Lisbon-Porto) - Date of construction: 1860 Pointed Arches Flat roadway Tie rods + anchorages Buttressing System Uncertain safety conditions  Survey requested

6. 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 - Existing anchorages much deteriorated and rather deformed (outward movement of masonry) (Buttresses overloaded) INTRODUCTION BOUTACA BRIDGE Results of the Survey carried out:  - Vegetation & lost of plaster (lack of maintenance) - Humidity & biological colonization (deficient drainage system) - Cracking in the buttress walls

7. 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 BOUTACA BRIDGE A) Structural Strengthening Additional “buttressing system” Patress plate Tie rod Recommended Remedial Measures:  - Lightening the buttresses  Tie rods + patress plates

8. 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 BOUTACA BRIDGE B) Other measures: - Waterproofing of the pavement and reconstruction of the drainage system - Cleaning and removal of vegetation - Replacement of plaster - Need for periodical visual inspections

9. 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 - Dimensions: 62m length, 4m width (larger span ≈ 12m ) INTRODUCTION BOUTACA BRIDGE DONIM BRIDGE DONIM BRIDGE (stone masonry)  - Local: Guimarães, North of Portugal - Purpose: roadway (major importance untill 2 centuries ago) - Date of construction: 15 th – 16 th century Semicircular Arches Flat roadway Pier + Cutwaters Flood arch Precarious safety conditions  Survey requested

10. 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 BOUTACA BRIDGE DONIM BRIDGE Results of the Survey carried out:  - Extensive longitudinal cracking in the left arch - Infesting vegetation all over the bridge - Longitudinal cracking in the flood (right) arch - Cutwater of the right pier highly damaged

11. 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 BOUTACA BRIDGE DONIM BRIDGE (Incremental principal strains) - 1 block foundation missing (underwater inspection) - A numerical analysis (3D, non-linear) carried out allow to confirm the damage observed and helped understanding its causes - Spandrel walls out of plumb Major problems :  - Outward movements of spandrel walls - Longitudinal cracking in the left and right arches - Pre-collapse of a cutwater (right pier)

12. 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 BOUTACA BRIDGE DONIM BRIDGE A) Left Arch (return joint’s thickness to its original width) ] profiles Ｕ shape tie rod Anchor rods Recommended Remedial Measures:  - Remove of the infill - 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

13. 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 BOUTACA BRIDGE DONIM BRIDGE B) Flood (right) Arch (prevent further spreading of the arch) - Full width anchors across the arch - Stitching anchors linking the arch to the spandrel walls Stitching anchors Full width anchors

14. 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 BOUTACA BRIDGE DONIM BRIDGE C) Other measures: - Dismantling and rebuilding of the right cutwater (same stones + steel cramps + steel latches) - 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

15. 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 BOUTACA BRIDGE DONIM BRIDGE FINAL REMARKS Common features to both examples Final Remarks  - Cleaning and removal of vegetation - Adoption of repair measures compatible with modern principles of structural intervention in the architectural heritage - Waterproofing and drainage of the pavement Thank you for your attention www.civil.uminho.pt/masonry