Ανθεκτικότητα Μεταλλικών Κατασκευών

[Ροδοπουλος]

Οι μεταλλικές κατασκευές αποτελούν πλέον μια διαδεδομένη κατασκευαστική λύση. Δυστυχώς,ομοίως με το σκυρόδεμα παρουσιάζουν προβλήματα ανθεκτικότητας και χρονοεπαρκειας.

 

Ξεκινάω με τα ISO

 

ISO 12944-1:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 1: General introduction

ISO 12944-2:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 2: Classification of environments

ISO 12944-3:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 3: Design considerations

ISO 12944-4:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 4: Types of surface and surface preparation

ISO 12944-5:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 5: Protective paint systems

ISO 12944-6:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 6: Laboratory performance test methods

ISO 12944-7:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 7: Execution and supervision of paint work

ISO 12944-8:1998 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Part 8: Development of specifications for new work and maintenance

ISO 19840:2004 Paints and varnishes -- Corrosion protection of steel structures by protective paint systems --

Measurement of, and acceptance criteria for, the thickness of dry films on rough surfaces

[Ροδοπουλος]

Atmospheric Corrosivity Categories and Examples of Typical Environments

(ISO 12944 Part 2 )

 

Galvanising Thickness

ISO 1461:1999

[Ροδοπουλος]

Design to avoid formation of humid and dusty zones. Provide drainage holes and

openings with a > 30mm to drain moisture and dirt. φωτό 1

 

Design to avoid entrapment of moisture and dirt and corrosive elements on or

between parts of structures. Use hermetic sealing for hollow sections, provide

drainage holes between inclined members and stiffeners. φωτό 2

 

Design with rounded angles to avoid corrosion. Edges and corners are corrosion sensitive points even when protected by coatings. φωτό 3

[Pappos]

Αυτοί που ασχολούνται με τις σιδηρές τα γνωρίζουν.

Επίσης γνωρίζουν ακόμη και το είδος της συγκόλλησης και σε ποια μορφή μπορεί να υπάρξει πρόβλημα κόπωσης στο μέλλον (από σκουριά, υγρασία και άλλους παράγοντες).

 

Όπως έχω πει πολλάκις το άθλημα σιδηρές στην Ελλάδα είναι νέο.

Το άθλημα σύμμεικτες γέφυρες, καλωδιακές, κρεμαστές σχεδόν άγωστο.

Το άθλημα ουρανοξύστες κρυφός πόθος.

[cohat]

Έχει ασχοληθεί κάποιος με το θέμα του προσδιορισμού χαρακτηριστικών υφιστάμενων μεταλλικών κατασκευών; Έχετε σχετική βιβλιογραφία και υπάρχουν στην Ελλάδα εταιρείες που να ασχολούνται με επιτόπου ή εργαστηριακό προσδιορισμών των χαρακτηριστικών αυτών; (όπως π.χ. του σκυροδέματος με κρουσιμετρήσεις, πυρηνοληψία κτλ)

[Ροδοπουλος]

Βέβαια και υπάρχουν ανάλογα τι αναζητάς.

[Ροδοπουλος]

Επιλέγω κομμάτια απο μια αναφορά με στατιστικά προβλήματα μεταλλικών

 

THE INFLUENCE OF VARIOUS ERRORS ON THE DURABILITY OF STEEL STRUCTURES FOR INDUSTRIAL BUILDINGS

 

1 INTRODUCTION

 

The industrial buildings with steel framing systems require large financial resources and, therefore it is essential that their service condition are permanently checked and kept under control.

 

The reliability of an industrial steel building is significantly influenced by the quality of design, quality of erection and also by the working environment.

 

Therefore the identification of any possible errors and the assessment of their influence on the loadbearing capacity of the structural steel members and on their durability are needed in order to set up the retrofitting solutions. Figure 1 presents a general picture of defects, errors, their influence on the structural performance and the principal means of intervention to remediate the damaging effects.

 

A survey carried out on steel industrial buildings in service has lead to the following

 

percentages of error sources:

 

9% - design errors;

 

6% - workshop fabrication errors;

 

40% - assembling errors on construction site;

 

45% - service errors.

 

2 DESIGN ERRORS

 

After a careful examination of the contract documents and especially the structural drawings and specifications, the following design errors have been identified:

 

unproper layout of industrial buildings with respect to neighbouring terrain features causing severe pollutant concentrations;

 

the use of carbon steels with low corrosion resistance instead of weathering steels;

 

ignoring certain phenomena such as natural ageing, corrosive fatigue and corrosive cracking that may favour the steel brittleness and premature failures;

 

selection of steel members with small cross-sectional areas vulnerable to corrosive

 

wearing and excessive number of change in size connections sensitive to corrosion;

 

the use of steel members with large perimeter/cross-sectional area ratios;

 

difficult access to the members surface for periodic painting and current maintenance;

 

inappropriate supporting conditions (purlins on trusses, trusses on columns) and also beam-column connections or column-footing connections causing accumulation of dust and/or water;

 

unsuitable bolt spacing leading to pieces tear out or to debonding of the adjacent components and to corrosive spots between them;

 

the use of intermittent fillet welds when steel structures are exploited in a corrosive atmosphere;

 

inappropriate design and construction of the roof cladding structure causing condensation and speeding up the corrosion process;

 

insufficient roof slope and insufficient overlap of the steel cladding panels causing water seepage;

 

inappropriate selection of the protective systems.

 

3 CONSTRUCTION ERRORS

 

The survey carried out on six steel framed industrial buildings has enabled the identification of the following construction errors:

 

lack of the mill test certificate;

 

disregarding the thicknesses of the steel members specified in the design drawings;

 

unproper welding procedures, causing residual stresses, stress concentrations and large distortions of the welded member;

 

insufficient tightening of the bolted connections;

 

incorrect surface preparation of the steel members before the application of the paint coatings;

 

deterioration of the preliminary corrosion protection systems during transport, handling, temporary storing and assemblage;

 

application of fewer paint coatings than specified in the project;

 

inadequate quality control of the protective system in workshop and for/or at the construction sites;

 

negligence in filling up the reception certificates both in workshops and/or construction sites.

[sovatzou]

Οι μεταλλικές κατασκευές αποτελούν πλέον μια διαδεδομένη κατασκευαστική λύση. Δυστυχώς,ομοίως με το σκυρόδεμα παρουσιάζουν προβλήματα ανθεκτικότητας και χρονοεπαρκειας.

οπότε ροδόπουλε μας μένει το thread "ανθεκτικότητα ξύλινων"

[Ροδοπουλος]

Μπα εκεί δεν το κατέχω!

[Ροδοπουλος]

Ενα γενικό άρθρο για steel galvanizing, εδω

 

Σε αντίθεση με το σκυρόδεμα (πολυσύνθετος ηλεκτρολύτης) η προστασία μεταλλικών είναι πολύ πιο απλή. Με βάση της κατηγορίες ISO επιλέγουμε το σύστημα.

 

Κατηγορία Ι

 

Αυτοκόλλητο Ανόδιο Galvanode Zinc Tape

 

Κατηγορία ΙΙ

 

BASF CONCRESIVE ZR

 

BASF MASTERSEAL 1810

 

SikaCor Zinc R (Ενδείκνυται και σε συγκολλήσεις)

Rustoleum 1085 Hard Hat Galva Zinc (Ενδείκνυται και σε συγκολλήσεις και σε χτυπήματα λόγω σκληρότητας). Εχει την δυνατότητα αυτο-κάλυψης περιοχών με εξαχνώσεις.

 

Κατηγορία ΙΙΙ

 

Galvotec Magnesium Ribbon

 

Low-Profile Plate Anodes

 

Mixed Metal Oxide Tubular Anodes (ASTM B338 Grade 1 or 2)

 

Anodeflex