arch 04 UNIVERSITY OF MINHO 0 Daniel Oliveira & Paulo Lourenço U N I V E R S I T Y O F M I N H O Barcelona, November REPAIR OF STONE MASONRY ARCH BRIDGES 4TH. CONFERENCE ON ARCH BRIDGES

arch 04 UNIVERSITY OF MINHO 1 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, 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)

arch 04 UNIVERSITY OF MINHO 2 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 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, But damage can be “minimized”… - By performing periodical inspections - By reducing the traffic load - By carrying out repair and strengthening measures… (Preventive maintenance)

arch 04 UNIVERSITY OF MINHO 3 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 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, … Survey and Repair of 2 Portuguese Masonry Arch Bridges  - Boutaca Bridge - Donim Bridge When dealing with architectural valuable constructions…

arch 04 UNIVERSITY OF MINHO 4 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, 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 Pointed Arches Flat roadwayTie rods + anchorages Buttressing System Uncertain safety conditions  Survey requested

arch 04 UNIVERSITY OF MINHO 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, 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) INTRODUCTION BOUTACA BRIDGE

arch 04 UNIVERSITY OF MINHO 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, Recommended Remedial Measures:  - Lightening the buttresses  Tie rods + patress plates INTRODUCTION BOUTACA BRIDGE A) Structural Strengthening Additional “buttressing system” Patress plate Tie rod

arch 04 UNIVERSITY OF MINHO 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, Waterproofing of the pavement and reconstruction of the drainage system INTRODUCTION BOUTACA BRIDGE B) Other measures: - Cleaning and removal of vegetation - Replacement of plaster - Need for periodical visual inspections

arch 04 UNIVERSITY OF MINHO 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, 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: 15 th – 16 th century INTRODUCTION BOUTACA BRIDGE DONIM BRIDGE Semicircular Arches Flat roadway Pier + Cutwaters Flood arch Precarious safety conditions  Survey requested

arch 04 UNIVERSITY OF MINHO 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, Results of the Survey carried out:  - Extensive longitudinal cracking in the left arch - Infesting vegetation all over the bridge INTRODUCTION BOUTACA BRIDGE DONIM BRIDGE - Longitudinal cracking in the flood (right) arch - Cutwater of the right pier highly damaged

arch 04 UNIVERSITY OF MINHO 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, block foundation missing (underwater inspection) INTRODUCTION BOUTACA BRIDGE 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)

arch 04 UNIVERSITY OF MINHO 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, INTRODUCTION BOUTACA BRIDGE DONIM BRIDGE Recommended Remedial Measures:  - Remove of the infill A) Left Arch (return joint’s thickness to its original width) - 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

arch 04 UNIVERSITY OF MINHO 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, INTRODUCTION BOUTACA BRIDGE 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

arch 04 UNIVERSITY OF MINHO 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, INTRODUCTION BOUTACA BRIDGE 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 - Cleaning and removal of vegetation - Repointing of the deteriorated masonry joints

arch 04 UNIVERSITY OF MINHO 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, Final Remarks  - Cleaning and removal of vegetation INTRODUCTION BOUTACA BRIDGE DONIM BRIDGE FINAL 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