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DURABLE STRUCTURESLNEC Lisbon 31 May - 1June 2012

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TWO CASE STUDIES ON CORROSION DAMAGE OF BRIDGES

Dr.-Ing. Ioan PEPENAR

ICECON GROUPThe Research Centre CERTINCON

Bucharest, Romania

CECO ICECON


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1. INTRODUCTION

● Corrosion damage by corrosion of structures in aggressive environments implications on resistance, stability and durability of structures.

● Durability of structures corrosion of steel / reinforcement steel.

● Content of paper two cases of steel and prestressed concrete old bridges damaged by corrosion in high humiditynatural environment.

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ICDS12 International Conference DURABLE STRUCTURES: from construction to rehabilitation LNEC • Lisbon • Portugal • 31 May - 1 June 2012

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2. DAMAGE CASES

Evaluation of the corrosion damage state of the bridges specific investigation techniques (on site and laboratory tests) results:

● bridge type, description of the structure/members;● service conditions: aggressivity of environments;● corrosion state; effects;● causes and corrosion mechanisms;● conclusions and intervention measures proposals.

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2.1. CASE 1: STEEL BRIDGE (1)

Structure: steel lattice girders; five spans; 315 m length; 1930’s

Fig. 1 Fig. 2 Fig. 3

Steel lattice girder bridge: general views.

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Fig. 4 Fig. 5

Main lattice girder: area reduction of the steel profiles above the reinforced concrete slab of the bridge carriageway due to localized corrosion differential aeration macro-cell, wetting-drying; profiles sectioned.

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ICECON

Fig. 6 Fig. 7

Carriageway load-bearing elements: localized corrosion of the longitudinal girders (I sections) and steel cross-girders, with significant area reduction in the zones with rainfall infiltrations; corrosion of the Zores steel profiles and local fractures due to rainfall infiltrations.


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ICECON

Fig. 8

Reinforced concrete slab: local corrosion damage of the concrete cover; advanced corrosion of the reinforcement around the steel elements of the lattice girders and between them.


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Causes of corrosion-induced damage:● high humidity environment;● water stagnation in the area of incorporation of the main lattice

girders in the concrete slab & wetting-drying cycles localized corrosion of steel profiles by differential aeration macro-cell;

● local deterioration of waterproofing rainfall infiltrations advanced corrosion of the Zores steel profiles and I sections;

● deterioration of protective paint localized corrosion of steel elements;

● absence of efficient intervention measures (repair, corrosion protection, waterproofing).

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2.2. CASE 2: PC BRIDGE (1)Structure: prestressed concrete adjacent beams and additional prestressing by external tendons; span of 30 m; 1950’s.

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Prestressed concrete bridge: general views.Fig. 9 Fig. 10


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2.2. CASE 2: PC BRIDGE (2)

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External prestressing tendons: deterioration of the initial protection of tendons; corrosion of prestressing wires.

Fig. 11 Fig. 12


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ICECON

Fig. 13 Fig. 14 Fig. 15

External prestressing tendons: fracture of prestressing wires due to corrosion and tendon split off; calcium carbonate crystallisation in the joint area between the prestressed beams.



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ICECON

Fig. 16

Sidewalks’ reinforced concrete cantilevers: damage of the concrete cover due to corrosion and freezing-thawing phenomena; corrosion of steel reinforcements.


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Causes of corrosion-induced damage:● high humidity environment;● rainfall infiltrations through the carriageway layers, through the

waterproofing and the joints between beams; ● deterioration of initial protection of the external prestressing

tendons access of water and oxygen to the surface of steel wires localized and generalized corrosion of steel significant reduction of wires areas and even fracture of somesteel prestressing wires;

● absence of efficient intervention measures (repair, corrosion protection, waterproofing).

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3. INTERVENTION MEASURES● Case 1: steel lattice girders bridge severe corrosion

damage state of structural elements, correlated with his age and current functional requirements close and replacement of the bridge.

● Case 2: prestressed concrete bridge advanced corrosion damage of the external prestressing tendons strengthening and corrosion protection of the bridge.

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4. CONCLUSIONS

● The results of the two case studies of old bridges, revealed the existence of a severe corrosion-induced damage, which affected the resistance, stability and durability of the bridges.

● There were proposed intervention measures to remedy existing damages replacement / strengthening and corrosion protection of the damaged elements, in order to assure normal service conditions of bridges.

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THANK YOU FOR YOUR ATENTION !

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