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Paper presented in 1-st International Scientific Conference on Professional Sciences, “Alexander Moisiu” University, Durres November 2016

ELEMENTS OF EUROPEAN NORMATIVE IN THE DESIGN OF STRUCTURES AND THEIR APPLICATION IN ALBANIA

FLORENC DABERDAKU1, DENADA CUNGE2

1Department of Engineering Sciences, Professional Studies Faculty, “Alexander Moisiu” University, Durres, Albania 2Water supply sanitation, Tirana Municipality, Tirana, Albania

Corresponding author e-mail: florencd@gmail.com

Abstract This study aims to show the most important elements of the design process. In the beginning there are some sets of factors to be selected. This may be done in accordance with respect to the location of the facility, its exposure factors and its seismic resistance required. Firstly, it is the Eurocode 0(also known as EN 1990) that gives anyone of us a deep insight about principles of the design in the Ultimate States, the classification of loads and the importance of environmental influences. There are also descriptions of the structural analysis which might include static and dynamic actions. Going further, in the Eurocode 1 we are shown a wide range of loads (live loads, wind loads, snow loads ect.) and their characteristic values. These are preceded by tables of construction materials (that will have their share in the permanent loads) in which weight per unit volume are shown. As per seismic calculations, Eurocode 8 furnishes us with ground conditions and seismic zones followed by the basic representation of the seismic action including the horizontal elastic response spectrum (and the vertical one) expressions followed by the design spectrum for elastic analysis with a particular emphasize of the behavior factor. It should be noted that in Eurocode 7 we are shown the main two formulas that engineers can use in order the value the capacity bearing of soils for design of foundations. Key words: Structural Engineering, European Normative, Static& Dynamic Loads, Environmental Factors, Seismic action, Capacity Bearing of Soils.

Short history of European Normative The structural Eurocodes make up an updated normative body whose purpose is the design of civil and industrial engineering facilities. Inside these normatives it is found the synthesis of the experience and traditions of 25 countries of the European Union (EU) and that of 3 countries of EFTA (European Free Trade Association). The above cooperation has given life to a set of unified design rules of worldwide level. In 1975 the Commission of the CEE began a program which aimed to eliminate the technical obstacles represented by the different Technical Normatives of each single state. Those differences were not always justified by solid motives but simply by traditions and consolidated customs. This initiativegave birth to the publication of the first documents’ series between 1975 and 1988. In 1989 the CEE decided to transfer the elaboration of the Eurocodes to CEN (ComitéEuropéen de Normalisation) for their publication as European Standarts.

The Eurocodes were first published as experimental documents (ENV); a period which lasted from 1992 to 1998. Nowadays they all are published as definitive normative (EN) Objective of eurocodes At this point we might say that the Eurocodes are offered to us as basic instruments for the achievement of the following objectives: • Improve the competitions of European

construction industry both within EU and outside it.

• Constitute the base for the European contracts in civil engineering works.

• Serve as reference for the determination of the performance of structural elements in front of the essential requirements.

Associated with the attainment of the above scopes are the following attended benefits: • Facilitate the free circulation of

constructions materials and products within

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the EU, which improves the running of the internal market.

• Make up the basics of comprehension between designers, customers, operators,

• users, business companies and producers. • Make up of a common base for research

and development in the field of structural • engineering

• Allow the preparation of reliable software’s.

Eurocodes General Plan and Specified Parts The general plane is represented by 58 documents of the Eurocode regrouped in the following Eurocodes:

Table 1. Abbreviation Determination Title

EN 1990 Eurocode 0 Basis of structural design

EN 1991 Eurocode 1 Actions on structures

EN 1992 Eurocode 2 Design of concrete structures

EN 1993 Eurocode 3 Design of steel structures

EN 1994 Eurocode 4 Design of composite steel and concrete structures

EN 1995 Eurocode 5 Design of timber structures

EN 1996 Eurocode 6 Design of masonry structures

EN 1997 Eurocode 7 Geotechnical design

EN 1998 Eurocode 8 Design of structures for earthquake resistance

EN 1999 Eurocode 9 Design of aluminium structures

Each of the Eurocodes includes the following parts shown in the table below:

Table 2. Eurocode Parts of each:

Eurocode 0 Basis of structural design

EN 1990 Basis of structural design EN 1990-A1 Basis of structural design for road bridges, footbridges and railway bridges

Eurocode 1 Actions on structures

EN 1991-1-1 Densities, self-weight, imposed loads for buildings. EN 1991-1-2 Actions on structures exposed to fire EN 1991-1-3 Snow loads EN 1991-1-4 Wind actions EN 1991-1-5 Thermal actions EN 1991-1-6 Actions during execution EN 1991-1-7 Accidental actions due to hit and explosion EN 1991-2 Traffic loads on bridges EN 1991-3 Actions induced by cranes and machinery EN 1991-4 Actions on silos and tanks

Eurocode 2 Design of concrete structures

EN 1992-1-1 General rules and rules for buildings EN 1992-1-2 Structural fire design EN 1992-2 Concrete bridges – Design and detailing rules EN 1992-3 Liquid retaining and containment structures

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Eurocode 3 Design of steel structures

EN 1993-1-1 Rules for buildings EN 1993-1-2 Structural fire design EN 1993-1-3 Supplementary rules for cold-formed members and sheeting EN 1993-1-4 Supplementary rules for stainless steels EN 1993-1-5 Plated structural elements EN 1993-1-6 Strength and Stability of Shell Structures EN 1993-1-7 Strength and stability of planar plated structures subject to out of plane loading EN 1993-1-8 Design of joints EN 1993-1-9 Fatigue EN 1993-1-10 Material toughness and through-thickness properties EN 1993-1-11 Design of structures with tension components EN 1993-1-12 Additional rules for the extension of EN 1993 up to steel grades S 700 EN 1993-2 Steel Bridges EN 1993-3-1 Towers and masts EN 1993-3-2 Chimneys EN 1993-4-1 Silos EN 1993-4-2 Tanks EN 1993-4-3 Pipelines EN 1993-5 Piling EN 1993-6 Crane supporting structures

Eurocode 4 Design of composite steel and concrete structures

EN 1994-1-1 Rules for buildings EN 1994-1-2 Structural fire design EN 1994-2 Bridges

Eurocode 5 Design of timber structures

EN 1995-1-1 Rules for buildings EN 1995-1-2 Structural fire design EN 1995-2 Bridges

Eurocode 6 Design of masonry structures

EN 1996-1-1 Common rules for reinforced and unreinforced masonry structures EN 1996-1-2 Structural fire design EN 1996-2 Design considerations, selection of materials and execution of masonry EN 1996-3 Simplified calculation methods for unreinforced masonry structures

Eurocode7 Geotechnical design

EN 1997-1 General rulesEN 1997-2 Ground investigation and testing

Eurocode 8 Design of structures for earthquake resistance

EN 1998-1 General rules, seismic actions and rules for buildings EN 1998-2 Bridges EN 1998-3 Assessment and retrofitting of buildings EN 1998-4 Silos, tanks and pipelines EN 1998-5 Foundations, retaining structures and geotechnical aspects EN 1998-6, Towers, masts and chimneys

Eurocode 9 Design of aluminum structures

EN 1999-1-1 General structural rules EN 1999-1-2 Structural fire design EN 1999-1-3 Structures susceptible to fatigue EN 1999-1-4 Cold formed structural sheeting EN 1999-1-5 Shell structures

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Definition of limit states, Eurocode 0 The limit states connected with: • The safety of people • The safety of the structure should be

classified as ultimate limit states. In certain circumstances the limit states concerned with the protection of the content should also classified as ultimate limit state. When of importance, the following limit states should be verified: • Loss of equilibrium of the structure or parts

of it with the whole structure considered as e rigid body

• Collapse due to excessive deformation, transformation of the structure or parts of it

• Collapse due to fatigue or from other effects depending on time

The limit states connected with: • The functioning of the structure or its

structural parts

• The comfort of the people • The aesthetics of the construction should be

classified as serviceability limit state. The verification according to serviceability limit state (SLS) should be based on criteria which are related to the following aspects:

a) Deformations which influence on: Ø The appearance Ø The users’ comfort Ø The functioning of the structure

b) Vibrations Ø Which may harm the users’

comfort Ø Which may limit the

effectiveness of the functioning of the structure

To be noted is the recommended values of ψ factors for buildings are according to the table below:

Table 3.

Where:

• Ψ0 is the combination value of the live load.

• Ψ1 is the frequent value of the live load. • Ψ2 is the quasi-permanent value of the live

load.

Live loads, Eurocode 1 According to the specific use of buildings the table below shows the categories:

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Table 4.

Category Intended specific use

A Areas for domestic and residential activities

B Areas for offices

C Areas where people can assemble (excluding areas belonging to category A,C or D)

D Areas for commercial activities

While the characteristic values of the distributed qk and concentrated load Qk are as follows:

Table 5.

Category of loaded area qk[kN/m2] Qk[kN]

Category A -slabs -stairs -balconies

from 1.5 to 2.0 from 2.0 to 4.0 from 2.5 to 4.0

from 2.0 to 3.0 from 2.0 to 4.0 from 2.0 to 3.0

Category B from 2.0 to 3.0 from 1.5 to 4.5 Category C -C1 -C2 -C3 -C4 -C5

from 2.0 to 3.0 from 3.0 to 4.0 from 3.0 to 5.0 from 4.5 to 5.0 from 5.0 to 7.5

from 3.0 to 4.0 from 2.5 to 7.0 from 4.0 to 7.0 from 3.5 to 7.0 from 3.5 to 4.5

Category D -D1 -D2

from 4.0 to 5.0 from 4.0 to 5.0

from 3.5 to 7.0 from 3.5 to 7.0

To be noted is that for local verifications a single concentrated load of Qk should be considered. Horizontal elastic and design spectrums, Eurocode 8  response spectrum, are as follows: 0 ≤ T ≤ TB Se(T) = ag*S*[1+T/TB*(η*2.5-1) ]EN 1998-1 (3.2) TB ≤ T ≤ TC Se(T) = ag*S*η*2.5EN 1998-1 (3.3) TC ≤ T ≤ TD Se(T) = ag*S*η*2.5*[TC/T] EN 1998-1 (3.4)

TD ≤ T ≤ 4sec Se(T) = ag*S*η*2.5*[TC*TD/T2] EN 1998-1 (3.5) While the expressions for the horizontal design spectrum are: 0 ≤ T ≤ TB Sd(T) = ag*S*[2/3+T/TB*(2.5/q-2/3)] EN 1998-1 (3.13) TB ≤ T ≤ TC Sd(T) = ag*S*2.5/q EN 1998-1 (3.14) TC ≤ T ≤ TD Sd(T) = ag*S*2.5/q*[TC/T] ≥ β*ag EN 1998-1 (3.15) TD ≤ T ≤ 4sec Sd(T) = ag*S*2.5/q*[TC*TD/T2] ≥ β*ag EN 1998-1 (3.16)

Table 6. Type 1 (M>5.5), parameters

Soil Category S TB TC TD A 1.00 0.15 0.40 2.00 B 1.20 0.15 0.50 2.00 C 1.15 0.20 0.60 2.00 D 1.35 0.20 0.80 2.00 E 1.40 0.15 0.50 2.00

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Table 7. Type 2 (M ≤ 5.5), parameters

Soil Category S TB TC TD

A 1.00 0.05 0.25 1.20

B 1.35 0.05 0.25 1.20

C 1.50 0.10 0.25 1.20

D 1.80 0.10 0.30 1.20

E 1.60 0.05 0.25 1.20

Bearing resistance calculation, eurocode 7 The design bearing resistance may be calculated from: R/A' = (π+2) cubcscic+ q (D.1) with the dimensionless factors for: the inclination of the foundation base: bc = 1 – 2α / (π + 2); the shape of the foundation:

sc = 1+ 0,2 (B'/L'), for a rectangular shape; sc = 1,2, for a square or circular shape. the inclination of the load, caused by a horizontal load H:

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With H ≤ A’ cu For Drained conditions, the design bearing resistance may be calculated from:

R/A' = c' Ncbcscic + q' Nqbqsqiq + 0,5 γ' B 'Nγbγsγiγ(D.2)

with the design values of dimensionless factors for: the bearing resistance: Nq = e π tanΦ' tan2 (45 + Φ'/2) Nc = (Nq - 1) cot Φ' Nγ = 2 (Nq- 1) tan Φ', where δ ≥ Φ'/2 (rough base) the inclination of the foundation base: bc = bq - (1 - bq) / (Nc tan Φ’ ) bq = bγ = (1 - α tan Φ’)2 the shape of foundation: sq = 1 + (B' / L' ) sin Φ', for a rectangular shape; sq = 1 + sin Φ', for a square or circular shape; sγ = 1 – 0,3 (B'/L‘ ), for a rectangular shape; sγ= 0,7, for a square or circular shape sc = (sqNq -1)/(Nq - 1) for rectangular, square or circular shape; the inclination of the load, caused by a horizontal load H: ic = iq - (1 - iq) / (Nc. tan Φ' ); iq = [1 - H/(V + A'c'cotΦ')]m; iγ = [1 - H/(V + A'c'cotΦ')]m+1. where: m = mB = [2 + (B '/ L' )]/[1 + (B' / L' )] when H acts in the direction of B'; m = mL = [2 + (L' / B' )]/[1 + (L' / B' ] when H acts in the direction of L'. In cases where the horizontal load component acts in a direction forming an angle θ with the direction of L', m may be calculated by: m = mθ = mL cos2θ + mB sin2θ.

References

1. Eurocode 0 Basis of structural design (UNI EN 1990: 2004)

2. Eurocode 1 Action on structures (UNI EN 1991-1-1: 2004)

3. Eurocode 7 Geotechnical design (UNI EN 1997-1:2005)

4. Eurocode 8 Design of structures for earthquake resistance (UNI EN 1998-1:2005)

5. Progettazione di strutture in calcestruzzo armato. Guida all’uso dell’Eurocodice 2. (A cura di aicap, 2008)

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