Unified Construction Code of Republic of Kosovo Chapter IV – Timber Structures
Chapter IV - Timber Structures
1
Unified Construction Code of Republic of Kosovo
Section 2 – Structural Chapter IV – Timber Structures
I. GENERAL PROVISIONS
1.1
1.1.1 This Technical Regulation (hereinafter referred to as the Regulation), in compliance with the fulfillment of the essential requirements for construction works, defines the technical characteristics for load bearing timber structures in buildings (hereinafter referred to as timber structures), the requirements for the design ,execution, usability, maintenance and other requirements for timber structures, and technical characteristics and other requirements for construction products intended to be incorporated into the timber structure (hereinafter referred to as construction products).
1.1.2 This regulation also applies to components of the building that are not integral parts of timber structures (non-structural elements - wood panels, wooden bulkheads, fences, fill, etc.) i.e., elements of timber structure that do not affect the mechanical resistance and stability of the building as a whole.
1.1.3 This regulation does not apply to final coatings of structural and non -structural parts of the buildings (coatings of ceiling, flooring, and walls) and wood products that serve as thermal, acoustic or other insulation.
1.2
1.2.1 Design, execution, maintenance and usage of building shall be such as to fulfill the requirements laid down in this Regulation
1.3
1.3.1 The timber structure is part of the building complex.
1.3.2 The fulfillment of the essential requirements of mechanical resistance and stability of the structure and of a part of the essential requirement of fire protection related to preservation of the load-bearing capacity of a timber structure in the case of fire during a certain period determined by a special regulation (hereinafter: resistance to fire), is attained with a timber structure that has the technical characteristics and meets the requirements laid down in this Regulation.
1.4
1.4.1 Construction products made of timber to which this Regulation applies are:
- Wood products (structural timber beams and wood based panels)
- Mechanical fasteners
- Adhesives
- Prefabricated elements
- Wood protection products,
- Other construction products for which requirements have been prescribed in Appendixes of this Regulation because of their installation along with the products from subparagraphs 1 to 5 of this paragraph.
1.5
1.5.1 Timber structures and construction products to which this regulation applies shall have the technical characteristics and meet all other requirements laid down in this Regulation.
1.5.2 Integral parts of a timber structures (bracings, foundations, etc.) and construction products that are incorporated in them, and which are not covered by this Regulation, must, in addition to provisions of this Regulation, fulfill the provisions of a special regulation which governs such Structures,
II. TECHNICAL CHARACTERISTICS OF A TIMBER STRUCTURE
2.1
2.1.1 The technical characteristics of a timber structure must be such that during the life of a building, while complying with the execution and maintenance specified in the design documentation of the timber structure, it withstands usual exploitation and environmental effects, so that during its execution and use, foreseeable impacts on a building do not cause:
- Collapse of a whole or part of the work,
- Major deformations to an inadmissible degree,
- Damage to other parts of the construction works or to fittings or installed equipment as a result of a major deformation of the load bearing construction,
- Damage by an event to an extent disproportionate to the original cause,
2.1.2 Technical characteristics of a timber structure, along with the requirements of Paragraph 2.1.1, must be such that in the event of an outbreak of fire, the load-bearing capacity of structure or part of it is preserved for a period of time defined in a special regulation.
2.1.3 Technical characteristics of a timber structure referred to in paragraph 2.1.1 and 2.1.2 are accomplished by designing and constructing the timber structure in accordance with the provisions of this Regulation.
2.1.4 Preservation of technical characteristics of a timber structure referred to in paragraphs 2.1.1 and 2.1.2 is achieved by the maintenance of a timber structure in accordance with the provisions of this Regulation.
2.2
2.2.1 If a timber structure has technical characteristics stipulated in paragraphs 2.1.1 and 2.1.2 of this Regulation, it is considered that the building meets the essential requirement of mechanical resistance and stability, and fulfills the specified resistance to fire.
2.2.2 When, in accordance with special regulations, the additional protection of a timber structure is necessary in order to meet the requirements of fire resistance (linings, sprinkler installation etc.), that protection shall be an integral part of the technical design documentation of the timber structure.
2.3
2.3.1 Technical characteristics of the timber structure must be such that, in addition to fulfilling the requirements of this Regulation, requirements of other specific regulations are also fulfilled which are necessary for fulfillment of other essential requirements for the building.
2.4
2.4.1 A timber structure shall, after the reconstruction of a building, have the technical characteristics as prescribed in paragraph 2.1.1 and 2.1.2 and paragraph 2.3.1 of this Regulation.
2.4.2 As an exception to paragraph 2.4.1, a timber structure must after reconstruction and adaptation of the building, which does not significantly affect the technical properties of the timber structure, have at least minimum of technical characteristics that it had before reconstruction and adaptation (hereinafter referred to as pre-existing technical characteristics).
2.4.3 It is considered that the reconstruction of a building should not affect significantly the technical characteristics of a timber structure if the pre-existing technical characteristics related to the mechanical resistance and the stability of the building are satisfactory and if they do not change more than 10 percent (eg. change of values of resultant forces in sections, etc.).
2.4.4 The provision of paragraph 2.4.2 of this Article does not apply:
- To multiple reconstructions of a building which change the pre-existing technical characteristics of a steel structure as a whole or in part, which characteristics are related to the mechanical resistance and the stability of the building,
- To reconstruction of a building whose timber structure is damaged so that a danger is present to the lives and health of people, environment, nature, other buildings and things, or the stability of the ground on the surrounding land.
2.5
2.5.1 Technical characteristics of protection of timber structures must ensure fulfillment of the requirements set on series of paragraphs 2.1 of this Regulation.
2.5.2 The protection of a timber structure must be conducted in such way as to ensure the attainment of technical characteristics of protection referred to in paragraph 2.5.1 of this Regulation.
2.5.3 If the protection is conducted in accordance to standards indicated in Appendix E of this Regulation, it is considered that the attainment of the protection characteristics referred to in paragraph 2.5.1 of this Regulation is ensured.
2.5.4 It is allowed to use other standards in addition to those indicated in Appendix E of this Regulation if the same level of compliance is attained.
2.5.5 The protection of a timber structure is considered to be an integral part of a technical solution in design documentation of the timber structure.
2.5.6 Protection of a timber structure is specified in more detail in Appendix E of this Regulation.
III. CONSTRUCTION PRODUCTS FOR TIMBER STRUCTURES
3.1
3.1.1 Construction products are produced in production plants (factories) outside of construction sites, unless specified otherwise in this Regulation for certain construction products.
3.1.2 An exception to paragraph 3.1.1 of this Regulation, the prefabricated elements of a timber structure (hereinafter: prefabricated elements) may be fabricated on a construction site for the needs of that construction site.
3.1.3 The construction site, in addition to being the place as defined by the Construction Law, implies, within the meaning of paragraph 3.1.2 of this Regulation, a production plant in which the prefabricated elements, applying suitable construction technology, are produced or fabricated for needs of a given construction site in accordance with the technical design documentation of a timber structure.
3.2
3.2.1 A construction product produced in a production plant (factory) outside of construction site may be incorporated into a timber structure if it fulfills the requirements laid down in this Regulation and if a certificate of conformity was issued for it in accordance with the provisions of a special regulation.
3.2.2 Prefabricated elements fabricated on the construction site for needs of that construction site may be incorporated into a timber structure if their usability is proven in accordance with the technical design documentation of a timber structure and this Regulation.
3.2.3 In the case of non-compliance of the construction product with technical specifications for that product and/or the technical design documentation of a timber structure, the producer of a construction product or the contractor constructing the timber structure must immediately stop the production/ installation of that product and undertake measures for the determination and removal of the faults which caused the lack of conformity.
3.2.4 If there is non-conforming delivery of a construction product, the manufacturer or importer must inform, without delay, all buyers, distributors, authorized legal person that took part in certifying the conformity and the Ministry of Trade and Industry.
3.2.5 The manufacturer or the importer and distributor of the construction product are obliged to undertake corresponding measures to maintain the technical properties of a construction product during handling, storing and transport, as is the contractor constructing the timber structure during transport, handling, storing and installation of a construction product.
3.3
3.3.1 Specific properties, attestations, certifications of conformity and marking of construction products, testing of construction products, and specifics during design and construction, necessary control procedures and other requirements that construction products must fulfill are laid down in Appendixes of this Regulation for:
- Wood products– in Appendix A,
- Mechanical fasteners – in Appendix B,
- Adhesives – in Appendix C,
- Prefabricated elements– in Appendix D, and
- Wood protection products – in Appendix E.
3.3.2 Certifications of conformity of products that are not covered by standards or deviate significantly from standards indicated in Appendixes A to E referred to in paragraph 3.3.1 of this Regulation are to be conducted according to technical specifications for such products.
3.3.3 Certifications of conformity, in terms of paragraph 3.3.1 and 3.3.2 of this Regulation, cover the activities of assessing conformity of construction products and, depending on the specified assessment system, issuing the certificate of factory production control or issuing the certificate of conformity of construction products.
IV. DESIGN OF TIMBER STRUCTURES
4.1
4.1.1 Timber structures must be designed in such way that during execution of work and service life of the building, all impacts on the timber structure must be predicted, resulting from the method and sequence of construction, from foreseeable conditions of normal use of the building and foreseeable impacts of the environment on the building.
4.1.2 Technical design documentation of timber structure, in accordance with this Regulation, must prove that the building will, during its construction and the designed usage life, fulfill the essential requirement of mechanical resistance and stability, fire resistance and other essential requirements in accordance with relevant regulations.
4.1.3 If not specified otherwise, with this or other regulations, the service life of the building referred to in paragraph 4.1.1 of this Regulation must be at least 50 years.
4.2
4.2.1 The mechanical resistance and stability and also fire resistance of the building are to be proven in the technical design documentation, with calculations of load-bearing capacity and serviceability of the timber structure for foreseeable actions and impacts on the building.
4.2.2 As an exception to paragraph 4.2.1 of this Regulation, fire resistance does not have to be proven if by a special regulation is not determined the period during which the ultimate limit state of the load-bearing capacity of the timber structure must be preserved during fire.
4.2.3 The calculations referred to in paragraph 4.2.1 of this Regulation are to be conducted by suitable calculation procedures that, when necessary, may be complemented by tests, in which all relevant parameters must be included.
4.2.4 Calculation models and other models must be such that, when the appropriate entry parameters are used and the modeling is carried out correctly, correspond to the behavior of the structure during construction and use.
4.3
4.3.1 Design of timber structures, shall be done according to European Standards specified in Appendix "F" of this Regulation.
4.3.2 The application of other rules for designing of timber structures which differ from the rules laid down in the European standards indicated in Appendix “F” of this Regulation is allowed, if it is proven that by applying those rules the requirements of this Regulation are fulfilled at least at the level specified in European standards in Appendix “F”.
4.3.3 Appendix “F” referred to in paragraph 4.3.1, specifies in more detail the designing of timber structures.
4.4
4.4.1 Glued timber must have a water content corresponding to the technical instructions of the adhesive manufacturer but not less than 9% and not more than 15% provided that the maximum difference between the water content of elements to be bonded must be ± 2%.
4.4.2 Initial imperfections in the middle of a linear element, i.e. the deviation from the direction of the axis of the linear element, and the slender beams where buckling may occur as in the frame, must not be greater than 1/500 of the length for glued laminated timber or 1/300 for structural timber.
4.5
4.5.1 It is not allowed incorporation of various types of fasteners in one joint, unless they have the same or similar mechanical properties.
4.5.2 It is not allowed to use different types of adhesives in construction of a single element of timber structure.
4.5.3 As an exception to paragraph 4.5.1, it is allowed the use of nails and screws when making glued joints, but only for tightening of glued joint, and not as bearing fasteners.
4.5.4 It is not allowed installation in timber structures, of structural timber indicated in Appendix "A" with water content greater than 22%.
4.5.5 It is not allowed installation in timber structures of timber elements that are not protected by preventive care processes in a manner to prevent re-wetting the timber during transport, processing, intermediate storage, assembly and use, avoiding direct contact with the water and soil, proper stacking and covering of timber elements.
4.6
4.6.1 Design documentation - a technical design documentation of timber structure, which is an integral part of the main project design of the building shall include in particular:
1. in the technical description
- A description of the impacts from the purpose and usage of building, and environmental influence on the properties of the timber structure,
- The data from the previous researches and data from other surveys and studies that can affect the properties of the timber structure,
- A description of a timber structure, including foundation,
- A description of method for execution of timber structure and installation of certain construction products,
- Exposure class of timber structural parts, including steel and concrete components,
- A description of the measures for structural protection, measures for chemical protection and special care if such is needed.
2. In the calculation of mechanical resistance and stability
- Information on the predictable actions and their impact on the structure of building,
- Information on the ground for foundation and earthquake zone,
- Calculation of load bearing capacity and serviceability of the timber structure for the foreseeable actions and impacts, and calculation of certain parts of the timber structure for all stages of transportation, handling, execution and usage of building,
- Calculation of global stability of the structure,
3. In the program of quality control and quality assurance of timber structures:
- Technical properties that construction products must possess in order to be installed in the timber structure, including adequate information for labeling of construction products, according to provisions of this Regulation,
- Tests and procedures to prove the usability of construction products that are manufactured at the site for the purposes of that construction site,
- Control of construction products incorporated into the steel structure that has to be conducted before their incorporation:
Test methods, for verification of load bearing capacity and serviceability of timber structures, including traditional fasteners and staples.
- Conditions for execution of works and other requirements that must be fulfilled during the execution of timber structure which affect the attainment of the designed and specified technical characteristics of timber structure and fulfillment of essential requirement of that building,
- Other conditions relevant for the fulfillment of requirements laid down in this Regulation and special regulations, and,
- Water content of elements of timber structure before incorporation in timber structure and water content of timber structure before junction with the other parts of the building.
4.6.2 Requirements from item 3, paragraph 4.6.1, depending on conditions, procedures and other circumstances of execution, may be elaborated in more detail in the execution project design documentation of the timber structure.
4.7
4.7.1 In addition to conditions laid down in paragraphs 4.1 to 4.6 of this Regulation, project design of a timber structure in which the execution of the timber structure is elaborated must contain technical solutions for:
- Elements of the timber structure and ways of their production or fabrication,
- Incorporation of elements into a timber structure, including the calculation and required properties of connections of the elements with other elements of the timber structure,
- Transfer and transport of elements of a timber structure (points of support and suspension and description of lifting systems, position of elements during transfer and transport, transport path, and other), and the designed weight and permitted weight tolerances of elements of the timber structure,
- Arrangement of props, necessary supports systems and other measures to ensure stability and prevent damage to elements of the structure during transport, incorporation and connection of elements of the structure.
4.8
4.8.1 In addition to conditions laid down in paragraphs 4.1 to 4.6 of this Regulation, the project design for reconstruction or renovation of a building, in which the timber structure is changed, must necessarily contain data on determined pre-existing technical characteristics of a timber structure
4.8.2 Pre-existing technical characteristics of a timber structure shall be determined by checking the documentation of the building, tests, calculations and other appropriate ways.
V. EXECUTION AND SERVICEABILITY OF TIMBER STRUCTURES
5.1
5.1.1 Execution of buildings that contain a timber structure must be such that the timber structure has technical characteristics and fulfills other requirements laid down in this Regulation, in accordance with the technical solution of the building and conditions for execution given in the project design, and so that it ensures the preservation of such properties and serviceability of the building during its life.