Workshop - Chronopoulos1

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Transcript Workshop - Chronopoulos1

EARTHQUAKE PLANNING AND PROTECTION ORGANIZATION (E.P.P.O.) ATHENS WORKSHOP / EC 8–3 : 2005 and nGCSI : 2012 APRIL 12, 2013 COUNCIL OF EUROPE EUROPEAN CENTRE ΟΝ PREVENTION AND FOR ΕCASTING OF EARTHQUAKES (E.C.P.F.E.) MAIN DIFFERENCES BETWEEN THE TWO CODES M. CHRONOPOULOS, LRC/NTUA/ GR

CODE for STRUCTURAL INTERVENTIONS (2012)

E a r r t t t h q u a k e e P l l l a n n i i i n g a n d P r r o t t t e e c c t t t i i i o n O r r g a n i i i z a t t t i i i o n o f f f G r r e e e e c c e e ( ( ( E .

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) ) ) TEAM FOR DEVELOPMENT OF CODE OF INTERVENTIONS ON REINFORCED CONCRETE BUILDINGS HARMONIZATION TEAM OF CODE OF INTERVENTIONS TO EUROCODES ENGLISH TEMPORARY VERSION CODE OF STRUCTURAL INTERVENTIONS 2012 FINAL HARMONIZED TEXT AUGUST 2012

• • Assessment and Retrofitting of existing structures for non-seismic actions is not yet covered by the relevant material-dependent Euro Codes (or existing National Codes).

The “framework” of the EC 8-3 (and the nGCSI) was specifically developed because :  For many older structures, seismic resistance was not considered during the original design/construction, whereas non-seismic actions were catered for, at least by means of “traditional” construction rules.

 Seismic hazard evaluations in accordance with present knowledge may indicate the need for retrofitting programmes and campaings (“active” or “passive”).

 Damage caused by earthquakes may create the need for major and costly structural interventions (repair/strengthening), not to mention other consequences.

DESIGN OF BUILDINGS FOR EARTHQUAKE RESISTANCE

ASSESSMENT AND RETROFITTING or STRUCTURAL (ASSESSMENT AND) INTERVENTIONS

• •

The EC8-3 : 2005

Main Body/Six (short) Chapters / approx. 30 pages, and Informative Annex A for RC Structures / approx. 20 pages.

The nGCSI : 2012, for RC Structures (only), Final Harmonized Text

Main Body and (Normative) Commentary / Eleven Chapters / approx. 350 pages. A new Chapter (no. 12) on Structural Additions or/and Changes of Use.

Retrofitting = Str. Interventions, Repair or/and Strengthening

THE RATIONALISM OF THE nGCSI : 2012, ITS CONTENTS

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SCOPE-FIELD OF APPLICATION-OBLIGATIONS AND RESPONSIBILITIES BASIC PRINCIPLES, CRITERIA AND PROCEDURES INVESTIGATION AND DOCUMENTATION OF THE EXISTING BUILDING BASIC DATA, ASSESSMENT AND REDESIGN + Four (4) Appendices (normative) ANALYSIS, BEFORE AND AFTER THE INTERVENTIONS BASIC BEHAVIOUR MODELS THE BEHAVIOUR OF EXISTING OR NEW RC ELEMENTS + INFILLS + Four (4) Appendices (normative) DESIGN OF INTERVENTIONS SAFETY VERIFICATIONS REQUIRED CONTENTS OF THE DESIGN FILE, ASSESSMENT AND REDESIGN CONSTRUCTION-QUALITY ASSURANCE-MAINTENANCE

NOTE 1

The definition of the LS of NC given in EC 8-3 is different than that given in EC 8-1.

Thus, the LS of NC is closer to the actual collapse and corresponds to the fullest exploitation of the deformation capacity of the structural elements.

NC

EC 8-1

SD

EC 8-3

NOTE 2

• Distinction between “ductile” or “brittle” structural elements and mechanisms, i.e. deformation or strength controlled ones.

See additional details and rules given by the nGCSI (μ   2 , μ φ  3).

• Distinction between “primary” (P) or “secondary” (S) seismic structural elements, using more or less conservative estimates of their capacities.

EC’s nGCSI : :

S/P+S  S/P+S  15% 25% .

EC8-3 / STATE OF DAMAGE IN THE STRUCTURE

Three (3) LIMIT STATES (LS’s), namely Near Collapse (NC), Significant Damage (SD) and Damage Limitation (DL).

The National Authorities decide whether all three LS’s shall be checked, or two of them, or just one of them.

NC :

P e = 2% in L t = 50 years, T r = 2.475 years

SD :

P e = 10% in L t = 50 years, T r = 475 years

DL :

P e = 20% in L t = 50 years, T r = 225 years _______________________________________________________

nGCSI : DIFFERENCES …

nGCSI / TARGET BEHAVIOUR PERFORMANCE LEVEL, SEISMIC ACTION

EQ A/LD PL B/SD C/NC 10% / 50 years 100% 50% / 50 years 60% A1 A2 B1 B2 C1 C2 IMPORTANCE : I / All, II / All but C2, III and IV / A1, A2, B1

Since existing structures (old ones, damaged or not) : (i) (ii) (iii) reflect the state of knowledge at the time of their construction, possibly contain hidden gross errors and problems, and may have been submitted to previous actions (accidental or not) with unknown effects, structural evaluation/assessment, structural intervention and redesign (if needed) are typically subjected to a different and a more complex degree of uncertainly than the design of new structures.

Therefore, different sets of partial safety and structural safety factors are required, as well as different analysis, dimensioning and verification procedures, depending (among others) on the completeness and reliability of the information available.

INVESTIGATION / DOCUMENTATION

EC8-3 /

Capacities

of ductile or brittle structural elements

• In general, mean value properties of the existing materials are used, as directly obtained from in-situ tests and from the additional sources of information, appropriately divided by the confidence factor (CF), accounting for the knowledge level (KL) attained. • Especially for brittle primary seismic elements, their strengths shall be based on material strengths divided by appropriate partial safety factors (γ m ), taking into account that the γ m values of the EC 8-1 are meant for the design of new buildings.

nGCSI :

DRL and a full set of mod. γ f and γ m , as well as of γ Sd and γ Rd .

Mat. properties :

f m or f m – S.

EC8-3 / KNOWLEDGE LEVEL (KL), CONFIDENCE FACTOR (CF)

Regarding the RC structural system, its components and its elements, for choosing the allowable type of analysis and the appropriate confidence factor values ...

Factors determining the appropriate knowledge level :

1) GEOMETRY

From original outline construction drawings with sample visual survey or from full survey

2) DETAILS

See Table

3) MATERIALS

See Table ____________________________________________________________

KL1 : KL2 : KL3 :

Limited Knowledge Normal Knowledge Full (?) Knowledge CF = 1,35 CF = 1,20 CF = 1,00

KL 1 2 3 DETAILS SIMULATED design + lim. in-situ inspection Original design + lim. in-situ inspection MATERIALS DEFAULT values + lim. in-situ testing Original design + lim. in-situ testing Extended in-situ inspection/testing Original design + lim. in-situ inspection Original design + lim. in-situ testing Comprehensive in situ inspection/testing ANALYSIS LINEAR ALL ALL CF 1,35 1,20 1,00 … outline or detailed dwgs, visual, full, limited, extended, comprehensive

MIN. REQUIREMENTS FOR INSPECTION (OF DETAILS) AND TESTING (OF MATERIALS) FOR EACH TYPE OF PRIMARY RC ELEMENT (BEAM, COLUMN, WALL) LEVEL Limited Extended Comprehensive DETAILS, PERCENTAGE OF ELEMENTS 20 50 80 MATERIAL SAMPLES PER FLOOR 1 2 3 Non-destructive combined with destructive testing … Cross-checks should be made between the data collected from different sources to minimize uncertainties.

EC8-3 / THE q – APPROACH

Generally, not suitable for cheching the LS of NC.

For RC structures of any type : • •

SD NC q

q’

1,5 4/3 . q

2,0 .

Higher values may be adopted if suitably justified with reference to the local and global available ductility (and overstrength …).

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nGCSI : A lot of provisions, rules, etc.

The m – approach …

Table 4.1 : Values of q*/q΄ ratio depending on the target Immediate use after the Performance level Life protection Collapse prevention earthquake (Α) (Β) (Γ) 0,6 with 1.0

Table C 4.4 : Values of behaviour factor q΄ for performance level B (life protection) Standards applied Favourable presence for design (and construction) or absence of infill walls (1) Generally unfavourable presence of infill walls (1) Substantial damage in primary elements Substantial damage in primary elements 1995<… 1985<…<1995(2) …<1985 No 3.0 2.3 1.7 Yes 2.3 1.7 1.3 No 2.3 1.7 1.3 Yes 1.7 1.3 1.1 (1) On the role and effect of infill walls see §5.9 και §7.4. (2) For buildings of this period, the values of the Table are valid provided that the check for non-formation of plastic hinges in column ends is made according to §9.3.3 (by satisfying ΣΜ Rc ≥1,3ΣΜ Rb ). For torsionally sensitive structures, or for those with at least 50% of the mass concentrated in the upper 1/3 of their height (inverted pendula), the values of the Table are multiplied by 2/3 but can not be lower than 1.0.

THE INFILLED RC FRAMES (OR QUASI-FRAMES)

Existing or even new/added infills … •

EC’s

nGCSI … A lot of provisions, rules, etc.

See a specific presentation.

nGCSI : 2012

ASPECTS OF MODELLING AND ANALYSIS

See the presentation by A. Kappos •

BEHAVIOUR OF EXISTING OR NEW ELEMENTS (RC, infills)

See the presentation by M. Fardis •

BEHAVIOUR OF REPAIRED/STRENGTHENED ELEMENTS (RC, infills)

See the presentation by S. Dritsos and T. Tassios •

FINAL CHECKS/SAFETY VERIFICATIONS

See the presentation by M. Fardis