seismic upgrade of factory buildings

7/28/2019 Seismic Upgrade of Factory Buildings

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POST-EARTHQUAKE INTERVENTIONS :PREVENTION AND SAFETY TECHNIQUES

FACTORY BUILDINGS:

THE MAIN FEATURES, THE

Author: Anna Marzo

Working group: Alessandra GugliandoloMaurizio Indirli

Giuseppe MarghellaMaria-Anna Segreto

INEFFICIENCIES AND THE

SUITABLE INTERVENTIONS

ACCORDING TO THE EUROPEAN

REGULATIONS



ENEA ACTIVITIES FOR SEISMIC PROTECTION

Supporting the Italian Civil Protection

L’Aquila earthquake (2009) - 6.3 Richter

damage/safety evaluation for cultural heritage

Emilia Romagna earthquake (2012) – 5.9 Richter

damage/safety evaluation for several typologies of

constructions



ENEA ACTIVITIES FOR SEISMIC PROTECTION

Research activity: innovative seismic protection devices

SEISMIC ISOLATION OF VALUABLE OBJECTS

T

ERCOLANO SHIP

Springs and hydraulic system

BASE ISOLATION OF BUILDINGS

O E

U

S P A C E P R O J E

Rolling element



EUROPEAN SEISMIC MAPS

Distribution of the seismicity on the European territory

form the highest (red) to the lowest (bleu) seismic areas

The reduction of the seismicity from south to north due to the plates localization. The more seismic countries are located along the Italy is located on the plate limitation

The earthquakes occur along the plate perimeter, when they move



FACTORY BUILDINGS: Surveyed multi storey typologies

Two levels

Alveolar panels

Notes:

Precasted buildings

Realization: 1960-2000

Reinfoced Prestressed

Concrete

Two-three levels

Precasted slab

ree eve s

Tile TT



Horizontal precast panels

FACTORY BUILDINGS : Cladding typologies

Vertical precast panels Notes:

Precasted vertical/horizontal panels

Panels-structure connections realized by steel anchorages

Regular opening

Claddings façades are very commonin industrial buildings. In these cases

it is very important to check the

fixing system to the buildingstructure taking into account thevertical force distributed on thesingle panel.The seismic action may beevaluated by considering a force

applied to the center of gravity of the

Brick masonry claddings

Notes:

Traditional brick masonry

claddings

Cladding fill the empties between the structures

Traditional mortar

element.



Connections among structural and completion elements

FACTORY BUILDINGS: Connections

Ad omega

CONNECTION TYPOLOGIES

Tiles simply supported by the beams

Beams simply supported by the pillars

Pillars fixed to foundation

Cladding panels connected to the structures by means of steel brackets

Beam

Mortar or rubber layer

Pillars

Beam

Pillar

Fork



Connections among structural and completion elements

FACTORY BUILDINGS: Connection cladding-beam and cover-beam

Ad omega CONNECTION TYPOLOGIES

✔Tiles simply supported by the beams

✔Beams simply supported by the pillars

✔ Pillars fixed to foundation

✔Cladding panels connected to the structures by means of steel brackets

weldingL shapedplate

ScrewΦ16 with washer

and nut

steel ancor plate

L SHAPED PLATE 130x65x10L=75mm

hole Φ17

buttonhole

steel ancor plate



FACTORY BUILDINGS: Current rules

UNI ENV 1992-1-3 30-09-1995. Eurocode 2. Design of concrete structures . General rules and rules forbuildings

Connections

• Damage due to cyclic deformation in plastic field should be considered; the strength design of the connections should be reduced in order to

taken into account of seismic stress, if it is required;

•in case of panel-bearing structures both r.c. and welded joints effectiveness should be experimentally tested;

•beam-pillar connections should guarantee the matching of both vertical and horizontal displacements and the stress should be transferred by

means of mechanical devices;•it is consented the realization of a sliding support at one end of the beam, but the sliding surface should be more extended then the seismic

displacement required;

•in case of connection between non monolithic parts ad hoc design criteria should be considered (three types are possible);

•Pillar-horizontal elements connection should be fix (rigid or elastic) when the pillars are isostatic elements;

•In general, the connections between both structural and completion elements should be guarantee the transmission of both static and seismic

The main requirements for structural elements and connections

UNI ENV 1998-1-4 31-10-1999. Eurocodice 8 - Design of structures for earthquake resistance. Part 1: General

rules, seismic actions and rules for building.

stress in the safe side, therefore simply friction connections are not permitted.

Beams

•The beam width should be greater then 20 cm, while for small beams (namely “flat beams”) it should not exceed the pillar width, increased on

both sides by the half height of the same beam;

•The ratio between transversal dimension of the beam (width/height) should not exceed 0.25;

•Axes of both beam and pillars supported (namely “in false”) should be aligned; in addition the beams should have at least two supports (pillars or

shell); the shell can not be supported on beam or plate “in false”;

•The critic zones are extended to 1 or 1,5 times the beam height for slow ductility class or high ductility class, respectively. In case of beam which

supports “in false” pillars the critic zone should be extended for two times of the beam high, starting from the beam-pillar node in all cases.

Pillars

•The pillar transversal section should be grater then 25 cm, while for small beams it should not exceed the pillar width, increased on both sides by

the half height of the same beam.

•In addition, the codes provide same limitation about reinforcement, which are evaluated case by case.



Buildings with double inclined beams: Lack of the support and collapse of the cover

FACTORY BUILDINGS: Damages surveyed after the sesmic events(may 20th and 29th)



Lack of support due to the break of the upper forks of the pillars: collapse of the cover

FACTORY BUILDINGS: Damages observed after the sesmic eventsin Emilia Romagna region (May 20th and 29th, 2012)



Collapse of the cladding panels

FACTORY BUILDINGS: Damages observed after the sesmic events inEmilia Romagna region (May 20th and 29th, 2012)

Connession panel-pillar



Collapse of the beam: separation of the two composing parts of the 2-body beam




Mixed precast reinforced concrete structures: Shear collapse of the masonry pears


Beneficial effects of the metallic ties




THE IMPORTANCE OF THE CONSTRUCTIVE DETAILS: These building are not collapsed thanks to the realization of good connections



FACTORY BUILDINGS: Reduction of the seismic vulnerability

PILLAR-BEAM

- Evaluation of the damages and of their

mechanisms;

- Evaluation of mechanical properties of the

constitutive materials;

- Evaluation and upgrading of stiffness,

strength and ductility against the design

stresses, by considering the suitable static

scheme (usually cantilever);

-

CONNECTIONS

Laboratorio LAERTE Anna Marzo ENEA - UNITA' UTSISM

FOUNDATION - Assessment of any damage and identification of its mechanisms;

- Knowledge of the type of soil for the characterization of the seismic

response with appropriate investigations (spreading seismic);

- Evaluation of the possibility of differentiated sags;

- Stiffness against rotation, such as to guarantee the joint at the base

of the pillars;

- Resistance against lateral actions, transmitted from the pillar (in thecontext of a hierarchy of resistors, the resistance of this element

should be oversized with respect to the superstructure)

beams and roof elements must not introduce significant bending

moments at the end of the connected elements since they are not

sized to absorb it;

-Simple supports must be transformed into hinges, in order to not

change the original static scheme;

- Sliding may also be permitted, but it should be, in any case,

limited by properly-sized restraints.

- Torsion rotation of the beams must be tackled ;

- The strength hierarchy should be considered whendimensioning the connections (links ductile and weaker than

the connected elements);

- The used fasteners (typically wall plugs) shall be more resistant

than the connecting devices set by them.



Beam


It has been providing some suggestions for professional engineers, suitable to evaluate quickly seismic safety and set upreasonable anti-seismic strengthening interventions for simple-storey. Reinforced prestressed precast concrete construction,taking into account both the safeguard of human life and the recovery of serviceability conditions, saving machinery andequipment.

Guideline for both local and global interventions on factory buildings developed by Eurocode.

SLIDING SUPPORTS • Evaluation of the section features and of the related forks (reinforcement, transversal

sections, and so on ;• Realization of constraint elements, when any fork is present

Pillar

Fork

Beam

Pillar

Sliding plain(teflon)




CONNECTIONS BETWEEN STRUCTURAL ELEMENTS

CONNECTION WITH COLD FORMED PROFILES

Beam

Pillar

• Evaluation of the section features and of the related forks (reinforcement,

transversal sections, etc)

• Any substitution of the forks with other support system in order to avoid the

beam overturning

Pre-existing hole

Steel pin

Supporting steel plate

Ancor steel bars



FOUNDATIONS


Ringing with concrete

Forks for both bars and brackets

connectionBars which connect the

concrete ring

Brackets

Requirements for foundation elements:

• Adequate stiffness against rotation, sufficient to ensure the joint at the base of the pillars.

• Adequate resistance against lateral actions transmitted from the pillar

Intervention’s category

• Connecting the plinth with the industrial floor

Improvement of the mechanical

properties of the soil

Connection steel bar

Additional concrete

cast

Industrial floor

Hole in the industrial

floorInjection with water-

concrete mixture

seismic upgrade of factory buildings

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