a case study in tuscany the san miniato...

2017-09-22

A case study in TuscanyThe San Miniato Bridge

Ing. Fabio Ricci - AICE Consulting Srl

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AICE CONSULTING S.r.l.

Presentation of the Company

www.aiceconsulting.it

COMPANY CERTIFICATION

Certification ISO 9001A.I.C.E. Consulting S.r.l. is a

DESIGN AND ENGINEERING SERVICES COMPANY founded in 1990

located in Pisa (Italy), providing HIGH-TECH

SPECIALIZED ENGINEERING SERVICES

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Our team is comprised of professionalengineers, architects and techniciansspecialized in various fields, performing theiractivities using state-of-the-art hardware andsoftware tools as well as sophisticated testingand measurement equipment.

Technical Department sub-divisions

Engineering service

European research projects

• 2011-13 PANTURA – European Flexible Processes and Improved

Technologies for Urban Infrastructure Construction Sites

• 2015-18 INSITER - Intuitive Self-Inspection Techniques

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Design division

The DESIGN DIVISION coordinates the

design and site management of both new

and existing civil and industrial

construction. Thanks to the high-degree of

specialization of the staff, long-term

experience in the field and the application

of standardized and well-established

procedures, this Division is able to rapidly

provide either preliminary or final detailed

planning of architectural, civil and

structural works, and mechanical and

electrical systems.

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Design division

Residential buildings

Buildings for business & services

Industrial buildings

Sport/recreational facilities

Bridges

Road networks

Repair of existing buildings

Strengthening of existing construction

Town planning/urbanization

Construction site safety plans

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Design division

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Diagnostic – inspection, survey and test

Specialized in structural and non-structural

diagnostics applied to large road and railway

infrastructures, existing construction, historical

and listed buildings

Direct & Topographic Surveys

Photogrammetry

Videoendoscopy

Tomography

Dynamic Tests

Strain Gauges

Pull-out and Pull-off Tests

Sclerometry

Sonic and ultrasonic Tests

Flat Jacks

Mortar Penetrometric Tests

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Diagnostic - structural assessments

The determination of the effects of loads on

existing structures

Model Analysis

Calibration of the model

Safety evaluation

Load-carring capacity

Identifying of the relevant structural issues

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Installation and management of the

monitoring systems for existing structures

Displacements

Deformation

Stress

Temperature

Humidity

Noise Level

Gas concentration

Light intensity

Cedimenti in funzione del tempo

Vertical displacement vs. time

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-6

-4

-2

0

dic 2002 giu 2003 gen 2004 ago 2004 feb 2005 set 2005

Monitoring

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LOCATION OF THE SAN MINIATO BRIDGE

In Italy

Within Tuscany

Satellite view

Road bridge over the Elsa

river constructed in 1968

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ACTUAL CONDITION OF THE STRUCTURES

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ASSESSMENT OF THE EXISTING BRIDGE

Operating procedure developed in Surebridge Project

Knowledge and

investigations

Search for existing documents

Survey Topographic surveyVisual inspectionGeometric and structural surveyDamage and degradation mapping

On site investigation Destructive testing (extraction of samples, compression of cores and

micro-cores, pull-out, pull-off)

Non-destructive testing (sclerometric, ultrasonic, video-endoscopy, X-ray,

thermography, depth of carbonation, load tests)

Dynamic acquisition

Laboratory tests on materials Compressive tests on concrete samplings

Tensile tests on reinforcement samplings

Structural

analysis

Schematization and definition of the model Geometry, constraints, materials, loads and masses

Analysis of the model with the finite

element method

Calibration of the model with dynamics

acquisition

Safety evaluation

Identifying of the relevant structural issues

Possible design of strengthening intervention

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KNOWLEDGE

Concrete deck and transversal beam reinforcements

SAN MINIATO BRIDGE

- ONE LANE 3 meters wide

- FOUR SPANS L=15+15+15+15m

- MAIN GIRDERS: four prestressed concrete beams, “I”

cross section, H=0.78m

- DECK: Reinforced concrete slab, thk 0.16m

ORIGINAL DESIGN DOCUMENTS (1968)

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Corrosion of pre-stressing wires

INVESTIGATION CAMPAIGN (2006)

VISUAL INSPECTION

Concrete spalling and

steel reinforcements corrosionDegradation of concrete surfaces

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Ultrasonic test

TESTS ON CONCRETE

Sclerometric test

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Pacometer test

TESTS ON STEEL

Removal of concrete cover

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DYNAMIC AQUISITIONS

NATURAL FREQUENCIES

Test Channel f1 (Hz) f2 (Hz)

AD1CH0 9.2 12.9

CH1 9.2 12.9

AD2CH0 8.6 12.5

CH1 8.6 12.5

AD3CH0 8.9 13.3

CH1 8.9 13.3

AD4CH0 8.6 -

CH1 8.6 -

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ANALYSIS OF THE EXISTING STRUCTURE

Longitudinal view

Transversal view

The finite element model has been created withthe software Straus 7®, using BEAM and PLATEelements;

FINITE ELEMENT ANALYSIS

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DYNAMIC MODAL ANALYSIS

MASS

PARTICIPATION FACTOR

Mode

Theoretical

frequency

(Hz)

X (%) Y (%) Z (%)

1 6.435 16.702 0.000 19.681

2 6.585 0.000 56.824 0.000

5 9.259 1.636 0.000 35.624

8 11.08 0.000 5.809 0.000

9 11.52 60.099 0.000 8.151

12 14.86 0.000 16.276 0.000

The theoretical and experimental frequencies werecompared in order to properly calibrate the model

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LINEAR STATIC ANALYSIS

Traffic loads for the maximum bending moment

(Italian regulation «D.M. 14 gennaio 2008»)

SectionMsd

(kNm)

Mrd

(kNm)

Vsd

(kN)

Vrd

(kN)

Internal girder 1231 991 360 285

Border girder 1156 962 260 285

Damaged girder 1156 721 260 285

The load-carrying capacity of the bridge

corresponds to the 51% of the traffic loads

assigned by the current Italian regulations.

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ANALYSIS IN THE TRANSVERSE DIRECTION

Msd

(kNm)

Mrd

(kNm)

Vsd

(kN)

Vrd

(kN)

Concrete Slab 41.4 16.6 154.0 78.2

The flexural and shear strength in the transverse

direction is provided by the concrete slab

The traffic loads should be placed in the most

unfavourable way accordingly to the current Italian

regulation

Load distribution for the transverse direction

(Italian regulation «D.M. 14 gennaio 2008»)

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THE SUREBRIDGE PROPOSAL

Refurbishment and widening

CFRP

LAMINATES

GFRP PANELS

EXISTING

DECK

SAN MINIATO BRIDGE

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DESIGN OF THE STRENGTHENING INTERVENTION

WIDENING HYPOTHESIS

Existing cross section Widened cross section

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Widened cross section Strenghtened section for

bending moment at midspan

STRENGTHENING HYPOTHESIS

Strenghtened section for

shear force at the supports

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STRENGTHENING HYPOTHESIS – GFRP PANELS

SKIN

FLUTEFLAT

MECHANICAL PROPERTIES

Elastic Modulus E

(MPa) Shear Modulus G

(MPa)Ex Ey Ez

Skin 32000 17000 10000 6000

Flat 12000 12000 6000 5000

Flute 9120 9120 5690 6080

GEOMETRICAL PROPERTIES

Thickness

(mm)

Height

(mm)

Spacing

(mm)

Skin 19.1 - -

Flat 8.5 111.8 102.4+8.5

Flute 1.12 111.8 70.0+1.12

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STRENGTHENING HYPOTHESIS – CFRP PRE-STRESSED LAMINATES

Pre-stressing technique studied at Chalmers

University of technology in Gothenburg;

No delamination from concrete at the CFRP

laminates ends;

Higher strengthening property compared to CFRP

passive laminates.

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FINITE ELEMENT ANALYSIS

NEW GFRP DECK

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FINITE ELEMENT ANALYSIS – GFRP PANELSEQUIVALENT CORE MODEL

X

Y

LAMINATE ELEMENT

PLY ELEMENT The spacial distribution of the webs is replaced

with an internal core with equivalent properties

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ANALYSIS RESULTS

(1) GFRP: H = 150 mm, webs in the transverse direction;



(4) CFRP: No. 1 laminates 80 mm x 1.4 mm;



(7) CFRP: No. 4 laminates 80 mm x 1.4 mm.

Section Msd (kNm) Mrd (kNm)

Widened Existing + CFRP +GFRP +CFRP+GFRP

Internal girder 1228 991 1251(4) 1408 (1) 1493 (1) (4)

Border girder 1382 962 1427 (6) 1434 (2) 1460 (1) (4)

Damaged girder 1382 721 1406 (7) 1428 (3) 1484 (1) (5)

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CONCLUSIONS

The load-carrying capacity of the bridge has been brought up to the 100% of the traffic loads prescribed

by the current Italian regulations;

The ultimate bending moment is increased from 721 to 1484 kNm, above the design value of 1382 kNm;

Combined use of CFRP and GFRP represents the best refurbishment solution;

Structural elements of the deck preserved;

No relevant demolition and waste production.

A CASE STUDY IN TUSCANY

THE SAN MINIATO BRIDGE

Copyright © 2015-2018. All rights reserved.

This publication is produced by SUREBRIDGE work group. Any duplication or use of objects such as diagrams in other electronic or printed

publications is not permitted without the author's agreement.

2017-09-22

This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and

demonstration under grant agreement No. 31109806.0009

SUREBRIDGE is co-funded by Funding Partners of The ERA-NET Plus Infravation and the European Commission. The Funding Partners of the

Infravation 2014 Call are:

MINISTERIE VAN INFRASTRUCTUUR EN MILIEU, RIJKSWATERSTAAT

BUNDESMINISTERIUM FÜR VERKEHR, BAU UND STADTENTWICKLUNG,

DANISH ROAD DIRECTORATE,

STATENS VEGVESEN VEGDIREKTORATET,

TRAFIKVERKET – TRV,

VEGAGERÐIN,

MINISTERE DE L'ECOLOGIE, DU DEVELOPPEMENT DURABLE ET DE L'ENERGIE,

CENTRO PARA EL DESARROLLO TECNOLOGICO INDUSTRIAL,

ANAS S.p.A.,

NETIVEI, ISRAEL - NATIONAL TRANSPORT INFRASTRUCTURE COMPANY LTD,

FEDERAL HIGHWAY ADMINISTRATION USDOT

a case study in tuscany the san miniato...

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