advances on structural design with timber in uruguay · advances on structural design with timber...

Advances on structural design with timber in Uruguay:Towards a proposal for a National Annex to Eurocode 5

Vanesa BañoLeandro DomenechGonzalo CetrangoloHugo O’NeillLaura Moya

Corresponding author:[email protected]

Presenter:Andrea Cardoso

1. Uruguayan forestry

Uruguayan forestry

The Uruguayan forestry sector has had a significant increase in wood volume during thelast thirty years as a result of a government policy to promote forest plantations


Uruguayan forestry

The Uruguayan forestry sector has had a significant increase in wood volume during thelast thirty years as a result of a government policy to promote forest plantations

The main industrial use of eucalyptus species is the production of pulp, while pineand part of the eucalyptus are used for construction products


Uruguayan forestry

An important volume of wood (1.7 million m3 of pine and 0.4million m3 of eucalyptus) have not current industrial destination


Uruguayan forestry

An important volume of wood (1.7 million m3 of pine and 0.4million m3 of eucalyptus) have not current industrial destination

The Uruguayan government has impulse the incorporation of timber for structural use, which implies the need for a national system of codes for timber products and for design and construction with timber

2. Design process 2.1. Stages in structural design

Design process of a structure

Structural planning

Definition of external loads

Determination of internal forces

Design of structural members

Detailing, drawing and preparation of schedules



Structural planning





Design codes

Introduction of security



Structural planning





Design codes

Introduction of security

ASD

or

LRFD

2. Design process 2.2. ASD and LRFD methods

ASD and LRFD methods

ASD:Allowable Strength Design

LRFD:Load and Resistance Factor Design





The LRFD method accounts separately for the predictability of applied loads through the use of load factors and for material and construction variability through resistance factors. TheASD method combines the two factors into a single factor of safety.



The variable factor of safety associated with the LRFD method is considered to be more consistent with probability since structures that have highly predictable loads (predominately dead load for example) do not require the same factor of safety as structures subjected to loads that are not very predictable (live and wind loads for example).



3. Codes 3.1. United States

Codes in the United States

In the USA the ASD method has been gradually replaced by the LRFD method




LRFD was introduced for:

• reinforced concrete structures in 1970 (ACI 318:1970)






• steel structures in 1986 (AISC 360:1986)







• timber structures in 2005 (NDS 2005)




The most recent editions of the United States codes for the design of timber and steel structures was developed in a dual format




• timber structures in 2005 (NDS 2005)

3. Codes 3.2. Europe

The Eurocodes are a set of European standards with the objectives of the elimination of technical obstacles to tradeand the harmonization of technical specifications

What Eurocodes are?


Purposes of the Eurocodes:

• a means to prove compliance with the requirements for mechanical strength and stability and safety in case of fire established by European Union law

The Eurocodes are a set of European standards with the objectives of the elimination of technical obstacles to trade and the harmonization of technical specifications

What Eurocodes are?




• a basis for construction and engineering contract specifications


What Eurocodes are?




• a basis for construction and engineering contract specifications

• a framework for creating harmonized technical specifications for building products


What Eurocodes are?


European Committee for Standardization (CEN) - Members


European Committee for Standardization (CEN) - Affiliates


European Committee for Standardization (CEN) - Partner Standardization Bodies

Eurocode 0 (EN 1990)

Basis of structural design










EN Eurocodes Parts




Actions on structures









EN Eurocodes Parts





Design of concrete structures








EN Eurocodes Parts






Design of steel structures







EN Eurocodes Parts








Design of timber structures





EN Eurocodes Parts










Geotechnical design



EN Eurocodes Parts











Design of structures for earthquake resistance


EN Eurocodes Parts


Eurocode 0 (EN 1990):Basis of structural design

Eurocode 1 (EN 1991):Actions on structures

Eurocode 2 (EN 1992): ConcreteEurocode 3 (EN 1993): SteelEurocode 4 (EN 1994): CompositeEurocode 5 (EN 1995): TimberEurocode 6 (EN 1996): MasonryEurocode 9 (EN 1999): Aluminum

Eurocode 7 (EN 1997): Geotechnical design

Eurocode 8 (EN 1998): Seismic design

Structural safety,serviceability

and durability


Design and detailing

Geotechnical andseismic design



Eurocode 5:Design of timber structures

Part 1 - General

• Part 1-1: Common rules and rules for buildings (EN 1995-1-1:2004)

• Part 1-2: Structural fire design (EN 1995-1-2:2004)

Part 2 – Bridges (EN 1995-2:2004)


Eurocode 5:Design of timber structures

Part 1 - General

• Part 1-1: Common rules and rules for buildings (EN 1995-1-1:2004)

• Part 1-2: Structural fire design (EN 1995-1-2:2004)

Part 2 – Bridges (EN 1995-2:2004)

LRFD


What National Annexes (NA) are?

Technical documents of national implementation with the objectives of the definition of the Nationally Determined Parameters (NDP) and, optionally, Non-Contradictory Complementary Information (NCCI) to Eurocodes




Parameters that stay open in the Eurocodes for the election of one national option, either because they are ignored in the Eurocodes or because they depend directly on the country




Parameters that stay open in the Eurocodes for the election of one national option, either because they are ignored in the Eurocodes or because they depend directly on the country

Information that helps the user to apply the Eurocode and the National Annexes

3. Codes 3.3. Nearby countries

Codes in nearby countries


Argentina

CIRSOC 601 (2013)


ASD


Argentina

CIRSOC 601 (2013)

Chile

NCh 1198 (2006)


ASD

ASD


Argentina

CIRSOC 601 (2013)

Chile

NCh 1198 (2006)

Brazil

NBR 7190 (2010)


ASD

ASD

LRFD

3. Codes 3.4. Uruguay


UNIT 33 (1991) – General actions on buildings

UNIT 50 (1984) – Wind actions on structures

Codes in Uruguay





Concrete design

UNIT 1050 (2005) – Design and construction of concrete structures

Codes in Uruguay





Concrete design

UNIT 1050 (2005) – Design and construction of concrete structures

Steel and timber design

IE3-53 (1953) – Design of steel structures

IE4-50 (1950) – Design of timber structures

Codes in Uruguay


There is not a national code for the design of timber structures in Uruguay

Codes in Uruguay



This can cause inconsistencies between the determination of mechanical properties of the material and the method used for the design by engineers or architects

Codes in Uruguay



This can cause inconsistencies between the determination of mechanical properties of the material and the method used for the design by engineers or architects

There is not a common criterion for all materials regarding deflection limits, acceptable vibration frequencies or time required of mechanical resistance in fire

Codes in Uruguay



Codes in Uruguay

Objective of the work

Design a code for timber structures for Uruguay whether developing an own codeor adopting an existing one

4. Methodology

Research project:

Technical documents for standardization of timber structures and buildings

4. Methodology

Research project:


Lines of work

1) Determining the physical and mechanical properties of timber in Uruguay

4. Methodology

Research project:


Lines of work


2) Design a code for timber structures for Uruguay

The results of this second line are presented in this work.

4. Methodology

Research project:


Lines of work




Tasks performed

Analysis of international codes for the design of timber structures

4. Methodology

Research project:


Lines of work




Tasks performed


Discussion about whether to develop an own code or adopt an existing one

4. Methodology

Research project:


Lines of work




Tasks performed


Discussion about whether to develop an own code or adopt an existing one

Drafting of a proposal for the Uruguayan National Annex to Eurocode 5

5. Results 5.1. Nationally Determined Parameters

2.3.1.2(2)P: Assignment of loads to load-duration classes

2.3.1.3(1)P: Assignment of timber constructions to service classes

2.4.1.(1)P: Partial factors for material properties

6.4.3(8): Tensile stresses in double tapered, curved and pitched cambered beams

7.2.(2): Limiting values for deflections of beams

7.3.3(2): Vibrations in residential floors

8.3.1.2(4): Lateral load-carrying capacity of nails in end grain

8.3.1.2(7): Species sensitive to splitting in nailed joints

9.2.4.1(7): Racking resistance of wall diaphragms

9.2.5.3(1): Modification factors for bracing systems

10.9.2(3): Erection tolerances for trusses: maximum bow

10.9.2(4): Erection tolerances for trusses: maximum deviation from vertical alignment

EN 1995-1-1: Nationally Determined Parameters (NDP)


EN 1995-1-2: Nationally Determined Parameters (NDP)

2.1.3(2): Maximum temperature rise for separating function in parametric fire

2.3(1)P: Partial factor for material properties in fire

2.3(2)P: Partial factor for mechanical resistance of connections in a fire situation

2.4.2(3): Reduction factor for combinations of actions

4.2.1(1): Procedure for determining cross-sectional properties


Partial factors for material properties

Quality control of

the timber

Quality control of

the construction

Factor for material

properties

Fundamental

combinations

NormalNormal 1,60

Intense 1,45

IntenseNormal 1,45

Intense 1,30

Accidental

combinations

Normal - 1,10

Intense - 1,00



Quality control of

the timber

Quality control of

the construction

Factor for material

properties

Fundamental

combinations

NormalNormal 1,60

Intense 1,45

IntenseNormal 1,45

Intense 1,30

Accidental

combinations

Normal - 1,10

Intense - 1,00

Quality control of the timber: certification

Quality control of the construction: judgment of the designer (relevance of the building, structural complexity, etc.)



Quality control of

the timber

Quality control of

the construction

Factor for material

properties

Fundamental

combinations

NormalNormal 1,60

Intense 1,45

IntenseNormal 1,45

Intense 1,30

Accidental

combinations

Normal - 1,10

Intense - 1,00

Eurocode 0 (EN 1990) – Annex 3

About 200 specimens of Uruguayan Pinus elliottii/taeda


Limiting values for deflections of beams

Criteria Limiting values

Integrity of the

constructive

elements

Floors with brittle partitions 𝑤𝑎𝑐𝑡 ≤ 𝑙/500

Floors with ordinary partitions 𝑤𝑎𝑐𝑡 ≤ 𝑙/400

Other

cases

With ceiling or false

plasterboard ceiling𝑤𝑎𝑐𝑡 ≤ 𝑙/300

Without ceiling or false

plasterboard ceiling𝑤𝑎𝑐𝑡 ≤ 𝑙/200

User comfort Floors and beams of floors 𝑤𝑖𝑛𝑠𝑡 ≤ 𝑙/350

Appearance of the building work 𝑤𝑛𝑒𝑡,𝑓𝑖𝑛 ≤ 𝑙/300

5. Results 5.2. Non-Contradictory Complementary Information

Non-Contradictory Complementary Information

• Relationship between UNIT Actions Codes and Eurocode 1

• External forces and load combinations

• Definitions for calculation of vertical and horizontal deflections

• Procedure for verification of floor vibrations


Relationship between UNIT Actions Codes and Eurocode 1UNIT 50 (1984): Wind actions on structures

Proposed methods:

1) Establish the wind actions on structures according to UNIT 50.



Proposed methods:


2) Convert the characteristic wind velocity (𝑣𝑘), defined by UNIT 50, in the basic wind velocity (𝑣𝑏), defined by Eurocode 1, and establish the wind actions on structures according to Eurocode 1.



𝑣𝑏 = 0,858 ∙ 0,676 ∙ 1,149 ∙ 𝑣𝑘 = 0,667 ∙ 𝑣𝑘

Proposed methods:





𝑣𝑏 = 0,858 ∙ 0,676 ∙ 1,149 ∙ 𝑣𝑘 = 0,667 ∙ 𝑣𝑘

Ground roughness

Proposed methods:





𝑣𝑏 = 0,858 ∙ 0,676 ∙ 1,149 ∙ 𝑣𝑘 = 0,667 ∙ 𝑣𝑘

Ground roughness

Sampling interval

Proposed methods:





𝑣𝑏 = 0,858 ∙ 0,676 ∙ 1,149 ∙ 𝑣𝑘 = 0,667 ∙ 𝑣𝑘

Ground roughness

Sampling interval

Return period

Proposed methods:



5. Results 5.3. Research topics

Future research topics Study of the embedment strengthfor the design of connections


Future research topics Study of the embedment strength for the design of connections

Determination of the sensitivity to splitting of local cultivated species




Study of the charring rates of local cultivated species




Study of the charring rates of local cultivated species

Determination of the physical and mechanical properties of sawn timber and engineered wood products. Develop an UNIT standard for visual grading and establish the correlation with the strength classes

6. Conclusions

Conclusions

Eurocode 5 parts 1-1 and 1-2 were proposed to be used in Uruguay for the design of timber structures. The adoption of the Eurocode 5 establishes a precedent in Uruguay for other construction materials

6. Conclusions

Conclusions


A National Annex to Eurocode 5 was proposed. This document contains the Nationally Determined Parameters and Non-Contradictory Complementary Information to Eurocode 5 for the Uruguayan conditions of timber design

6. Conclusions

Conclusions


A National Annex to Eurocode 5 was proposed. This document contains the Nationally Determined Parameters and Non-Contradictory Complementary Information to Eurocode 5 for the Uruguayan conditions of timber design

In order to complete the National Annex to Eurocode 5 with information about local cultivated species and local conditions a list of research topicswas recommended

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