Foreword

TCVN 9311-5:2012 is completely equivalent to ISO 834-5:2000.

TCVN 9311-5:2012 is converted from TCXDVN 345:2005 (ISO 834-5:2000) according to the regulation in clause 1 Article 69 of the Law on Standards and Technical Regulations and point a) Clause 1 Article 7 of the Government’s Decree No. 127/2007/ND-CP dated August 1, 2007 detailing the implementation of some articles of the Law on Standards and Technical Regulations.

TCVN 9311 series under the general title “Fire resistance tests – Elements of building construction” includes the following parts:

– TCVN 9311-1:2012, Part 1: General requirements.

– TCVN 9311-3:2012, Part 3: Commentary on test method and test data application.

– TCVN 9311-4:2012, Part 4: Specific requirements for loadbearing vertical separating elements.

– TCVN 9311-5:2012, Part 5: Specific requirements for loadbearing horizontal separating elements

– TCVN 9311-6:2012, Part 6: Specific requirements for beams.

– TCVN 9311-7:2012, Part 7: Specific requirements for columns.

– TCVN 9311-8:2012, Part 8: Specific requirements for non-loadbearing vertical separating elements.

ISO 834 series Fire-resistance tests – Elements of building construction also includes the following parts:

– ISO 834-9:2003, Fire-resistance tests – Elements of building construction – Part 9: Specific requirements for non-loadbearing ceiling elements

– ISO/DIS 834-10, Fire resistance tests – Elements of building construction – Part 10: Specific requirements to determine the contribution of applied fire protection materials to structural elements

– ISO/DIS 834-11, Fire resistance tests – Elements of building construction – Part 11: Specific requirements for the assessment of fire protection to structural steel elements

TCVN 9311-5 : 2012 was drafted by the Institute of Architecture and Urban-Rural Planning – Ministry of Construction, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology and Quality, and published by the Ministry of Science and Technology.

1. Scope

This standard specifies the procedures to be followed to determine the fire resistance of loadbearing horizontal separating elements when exposed to heating from the underside.

These tests are also suitable for the evaluation of loadbearing horizontal separating elements incorporating beams, when the elements cannot be tested in conjunction with the floor or roof construction without such beams. However, data cannot be directly transferred from one type of test to another.

The results of these tests may be applied to similar elements not tested, provided that these fall within the field of application rules given in the various parts of this series or where extended application is made in accordance with ISO/TR 12470. As ISO/TR 12470 only provides general guidance, extended application of specific case should only be undertaken by experts in fire-resistant construction.

2. Normative references

The following normative references are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

TCVN 9311-1 : 2012 ¹⁾, Fire-resistance tests – Elements of building construction – Part 1: General requirements.

TCVN 9311-6 : 2012 ¹⁾, Fire-resistance tests – Elements of building construction – Part 6: Specific requirements for beams.

ISO/TR 12470, Fire-resistance test – Guidance of the application and extension of results.

ISO/IEC 13943, Fire safety – Vocabulary.

3. Terms and definitions

For the purposes of this standard, the terms and definitions given in TCVN 9311-1:2012 and ISO/IEC 13943 and the following apply.

3.1. Beams

Horizontal structural members forming part of the structural frame of a building, such as joists, purlins, secondary and main beams.

NOTE: Such members may be either attached to, or separate from, the construction that they have to support.

3.2. Exposed length

The length of the test specimen exposed to heating from the underside in the heating conditions of the test furnace.

3.3. Exposed width

The width of the test specimen exposed to heating from the underside in the heating conditions of the test furnace.

3.4. Floor

Horizontal loadbearing separating structure of a building.

3.5. Horizontal separating element

A loadbearing floor or roof construction acting as a fire separating element in a horizontal orientation. These divide a building into fire compartments and/or protect parts of a building from an adjoining building, preventing fire spread to adjoining compartments and/or adjoining buildings.

3.6. Plenum

An enclosed concealed space between the ceiling and roof but not purposely designed for the movement of air.

3.7. Roof

The uppermost horizontal loadbearing separating structure of a building.

3.8. Span

The distance between the centres of two supports.

3.9. Specimen length

The overall length of the test specimen.

3.10. Specimen width

The overall width of the test specimen.

3.11. Suspended ceiling

A horizontal non-loadbearing protective membrane suspended from or fixed directly to a loadbearing horizontal separating element, and its supporting structure, including any hangers, technical systems (lighting and ventilation systems), utilities (electrical, thermal, acoustic insulation) and access panels.

4. Symbols and abbreviated terms

The symbols and abbreviated terms appropriate for the test are given in TCVN 9311-1:2012 and are defined as follows:

5. Test equipment

The equipment used in these tests includes a test furnace, loading equipment, restraint, supporting frame and supporting tools as specified in TCVN 9311-1:2012.

6. Test conditions

6.1. General requirements

The heating and pressure conditions, furnace atmosphere, and loading conditions shall comply with the requirements specified in TCVN 9311-1:2012.

6.2. Restraint and boundary conditions

Restraint and boundary conditions shall comply with the requirements specified in TCVN 9311-1:2012 and those in this standard.

6.3. Loading

6.3.1. All loadbearing horizontal separating elements shall be tested while subjected to the design load in accordance with the requirements in 6.3. a), b) or c) of TCVN 9311-1:2012. The client requesting the test should be consulted as to the structural conditions to which the design was made. The material properties used for calculating the load shall be clearly stated and the source given.

6.3.2. When the proposed test specimen is smaller than the element used in practice, the size and type of test specimen and the level of loading and support conditions, shall be selected so as to give the same failure mode (e.g. bending, shear, bond or anchorage failure) for the test specimen as for the construction that it represents; that is, the loading applied during the test shall be at the same level as for the actual structure. In cases where the failure mode is difficult to predict, two or more individually designed tests shall be conducted to cover all possible failure modes.

6.3.3. The magnitude and distribution of the load shall be such that the maximum moments and shear forces generated are equal to or greater than those expected in practice.

6.3.4. The loading system shall be capable of producing the required load distributed uniformly over the surface by weights or hydraulic jacks, such that at any one point the load does not exceed the total load by more than 10%. Higher loading is permissible when it is necessary to adjust for concentrated loading or to make up the loading on members. The contact area between the loading point and the surface of the horizontal separating element shall be transmitted through pads not less than 0.01 m² nor greater than 0.09 m² individually, and not exceed 16% of the total surface area. If pads are made of steel or similarly high thermal conductivity material, they shall be insulated from the surface of the specimen. The loading system, excluding the loading points, shall not inhibit the free movement of air, and no part of the loading equipment shall be closer than 60 mm to the surface.

6.3.5. The loading system shall be capable of adjustment to compensate for the permitted maximum deflection of the test specimen.

6.3.6. When the floor or roof contains one or more structural beams, the additional requirements specified in TCVN 9311-6 : 2012 shall apply. When the loading requirement for a horizontal assembly includes the application of additional point or line loads on beams that are an integral part of the assembly, the loading equipment shall be capable of producing such loading.

7. Test specimens

7.1. Specimen design

The test specimen shall be designed to have the representative structural features necessary for it to achieve the desired performance. Different designs of the same detail should be avoided.

When testing in conjunction with a ceiling, the dimensions of the ceiling shall be L_exp and W_exp and the properties of the ceiling shall be evaluated as part of the total assembly and the following requirements shall be met:

a) The ceiling shall be erected from below by using the methods and sequence given in the installation instructions or provided by the test sponsor and shall be representative of actual conditions of use.

b) The test specimen shall include the components used in actual practice to suspend or fasten, and allow for expansion and discontinuity. When the ceiling incorporates services (such as lighting or ventilation systems) that are an integral part of the ceiling design, these components shall be included in the test specimen and be distributed as in actual practice.

c) When the ceiling is designed with longitudinal and transverse joints, the test specimen shall include both types of joint. Secondary supporting members carrying ceiling components shall be tightly butted together with no gaps, unless gaps are a feature of the design. In which case, the gaps shall be representative of those used in actual practice and positioned within the ceiling, not at the perimeter.

d) The edges, abutments and fixings shall be representative of those used in actual practice. The ceiling shall be installed in such a way as to prevent a loss of performance due to thermal expansion either longitudinally at the edges, or in a manner not anticipated by the ceiling system. These components shall be tightly fitted to the perimeter to enable the expansion properties of the element and the perimeter details to be evaluated.

e) When the longitudinal and transverse features of a ceiling construction are dissimilar, and the performance of the test specimen will vary depending on whether the longitudinal axis is parallel to the major axis, the ceiling shall be configured to represent the worst-case condition by positioning the significant components parallel to the longitudinal axis. When the orientation is not known, two separate tests shall be conducted with the components perpendicular and parallel to the longitudinal axis.

f) When services are not an integral part of the ceiling but could subsequently be installed and may affect the fire resistance of the ceiling, separate tests shall be conducted with the services fitted to the ceiling.

7.2. Specimen size

7.2.1. Simply-supported floors

7.2.1.1. The standard conditions (simply-supported floors) are given in 7.2.1.2 and 7.2.1.3. The arrangement of a simply-supported floor placed in a test furnace is illustrated in Figure 1.

7.2.1.2. The exposed length (L_exp) shall not be less than 4 m. The span between supports (L_sup) shall equal the exposed length (L_exp) plus the length of bearing at each end up to a maximum of 100 mm. The specimen length (L_spec) shall be the exposed length (L_exp) plus at each end a maximum of 200 mm.

7.2.1.3. The specimen width (W_spec) shall be the exposed width (W_exp) and shall not be less than 3 m. Except that the specimen width may be not less than 2 m for simply-supported, single-span elements not incorporating a structural beam or a ceiling.

KEY

1. Test furnace

2. Test assembly

3. Rollers and bearings

4. Insulating material

Figure 1 – Example of a simply-supported test specimen placed in a test furnace

7.2.2. Actual conditions

7.2.2.1. Floor constructions supported under actual conditions are dealt with in 7.2.2.2 to 7.2.2.5.

7.2.2.2. The exposed length (L_exp) shall be not less than 4 m when the actual exposed length of the floor exceeds the length that can be accommodated in the furnace. For constructions designed for an actual exposed length less than 4 m the actual exposed length shall be tested. The length of bearing (built-in) shall not exceed the actual bearing length. The specimen length (L_spec) shall equal the exposed length (L_exp) plus a maximum of 200 mm at each end.

For assemblies involving two-way slabs, a minimum span of 4 m is not appropriate as only a part of the slab is under bending, the remainder being restrained. As such, a longer span to create more than 4 m under positive bending moment should be selected. If X % of the slab length is under positive bending, the total length is determined by L_exp= 4 x 100/Xm.

7.2.2.3. The exposed width of the specimen (W_exp) shall not be less than 3 m. If the design exposed width is less than the actual 3 m, then the actual exposed width shall be tested.

7.2.2.4. For single-span elements, the supported width (W_sup) shall equal the exposed width (W_exp).

7.2.2.5. For elements, including two-way spanning members, the clear span (W_sup) shall equal the exposed width (W_exp) plus half the bearing length at each transverse edge. The bearing length shall be selected so that the difference between the supported width (W_sup) and the exposed width (W_exp) is not greater than it would be in practice. The specimen width (W_spec) shall be the exposed width (W_exp) plus a maximum of 200 mm at each end.

7.3. Number of specimens

The number of specimens shall comply with the requirements specified in TCVN 9311-1:2012.

7.4. Conditioning of test specimens

At the time of the test, the strength and moisture content of the test specimen shall be representative of the conditions expected in normal use. The test specimen shall include the incorporated fillers and connectors. Guidance on the conditioning of test specimens is given in TCVN 9311-1:2012. Once equilibrium has been achieved, the moisture content or state of dryness shall be determined and recorded. The supporting construction, including the furnace wall lining in the test frame, is not required to comply with this requirement.

7.5. Installation of test specimens and restraint

7.5.1. Loadbearing horizontal separating elements shall be exposed to heating either supported on roller bearings (simply-supported) or constructed with boundary conditions as in practice. When the support and restraint correspond to those used in practice, they shall be described in the report and the test results shall have a higher level of precision.

7.5.2. Test specimens representative of a normal floor or roof shall be tested on roller bearings. When boundary conditions are fixed, the test construction may be erected as in practice using concrete or steel plates as supports.

7.5.3. Simply-supported test specimens shall be arranged to allow freedom for longitudinal movement and vertical deflection and to preclude any frictional restraint.

7.5.4. Restraint designed to restrict longitudinal thermal expansion or rotation shall be designed or constructed in accordance with the forces anticipated, given the thermal expansion and restraint requirements.

7.5.5. When testing more than one beam simultaneously, each beam shall be exposed as specified and shall be loaded to perform independently of each other.

7.5.6. Any gaps at the perimeter shall be filled with non-combustible material that does not inhibit differential movement.

7.5.7. Resilient fire-resisting materials shall be used to seal and protect the supports, preventing hot gases from affecting the boundary conditions during the test.

7.5.8. When the test specimen is smaller than the opening of the test frame, supporting constructions shall be used to reduce the opening to the required size. The supporting constructions do not need to be conditioned like the test specimen, except in cases where conditioning the supporting construction could stabilize the performance of the specimen. When a beam is used between the supporting construction and the separating element, the design of the connection between the separating element and the beam, including any fixing details and materials used to make the connection, shall be used as in practice and shall be considered as part of the test specimen. The supporting construction shall be considered as part of the test frame.

7.5.9. All connections between the test specimen and the supporting construction or test frame shall provide a normal level of restraint. The rigidity of the supporting construction shall also be sufficient to provide a normal level of restraint.

8. Installation of measuring devices

8.1. Test furnace thermocouples

Thermocouples shall be installed to measure the furnace temperature and shall be distributed appropriately to obtain reliable temperature readings across the exposed faces of the test specimen. The thermocouples shall be attached and positioned in accordance with the requirements in TCVN 9311-1: 2012.

The number of thermocouples shall be not less than one for every 1.5 m2 of exposed surface area of the test specimen. There shall be a minimum of four thermocouples for any test and each thermocouple shall be oriented so that its “A” face is directed towards the floor of the test furnace.

8.2. Thermocouples on the unexposed surfaces

Thermocouples on the unexposed surfaces of the test specimen shall be firmly attached and positioned in accordance with the requirements in TCVN 9311-1: 2012. When the floor or roof specimen contains one or more loadbearing beams, thermocouples shall be placed at representative locations along each beam as required in TCVN 9311-6: 2012 for beams.

Unexposed surface thermocouples shall not be placed closer than 100 mm to the edges of the test specimen.

8.3. Deflection measurement

The zero point of the test shall be the deflection measured after loading is applied immediately before the start of the test, prior to heating and after the deflection has stabilized.

The vertical deflection along the longitudinal axis shall be measured at mid-span. For test specimens incorporating beams, the longitudinal deflection of the beam shall also be measured at mid-span.

Deflection measurements shall be taken at multiple locations to determine the maximum movement.

9. Test procedures

9.1. Loading and application

The application and verification of loading for horizontal elements shall comply with the requirements in TCVN 9311-1:2012 and 6.3 of this standard.

9.2. Furnace control

The measurement and control of conditions such as temperature and pressure in the test furnace shall comply with the requirements in TCVN 9311-1:2012.

9.3. Measurements and observations

The monitoring of test specimens for compliance with the loadbearing capacity, integrity and insulation criteria shall be conducted by measurements and observations in accordance with the requirements in TCVN 9311-1:2012

10. Performance criteria

The fire resistance of loadbearing horizontal separating elements shall be assessed and compared against the loadbearing capacity, integrity and insulation criteria specified in TCVN 9311-1:2012.

11. Evaluation of test results

The test shall be considered valid if the procedures were conducted in accordance with the instructions within the characteristic limits for the relevant requirements such as: test equipment, test conditions, specimen preparation, installation of measuring devices and test procedures, and shall comply with the requirements in this standard.

The test shall also be considered valid when the exposure conditions related to furnace temperature, pressure and ambient temperature exceed the upper limits of the tolerances specified in this standard and TCVN 9311-1:2012.

12. Expression of test results

The results of the fire resistance test shall be expressed in accordance with the requirements in TCVN 9311-1:2012.

When a test is conducted on a specimen bearing a design load specified by the test sponsor to be less than the maximum that could occur under an acceptable code of practice, the loadbearing capacity shall be recorded in the statement of results using the term “restricted”. Details shall be given in the test report of this load discrepancy.

13. Test report

The report shall comply with the requirements in TCVN 9311-1:2012.

Annex A (Informative) Field of direct application of test results

The results of a fire resistance test may be directly applied to similar loadbearing horizontal separating elements not tested, provided that the conditions below are true:

a) For loadbearing horizontal separating elements:

1) The type of construction (beam and slab) is unchanged;

2) The ratio of the perimeter to the cross-sectional area of the beam is not increased;

3) The thermal inertia (expressed as √kρc) of the upper slab is not increased;

4) The thermal conductivity of the filling material between the beam and slab is not increased.

b) For suspended ceilings:

1) The permeability of the upper slab is unchanged;

2) The thickness of the tiles is not reduced;

3) The design and material of the tiles are unchanged;

4) The area of the tiles is not increased and the ratio of the edges of the tiles is unchanged;

5) The method of fixing to the supporting construction is unchanged;

6) The depth of the air space is not reduced;

7) The length of the hangers is not increased by more than X %;

8) Allowance for expansion of the suspension system and of the supporting construction is not reduced;

9) The distance between the hangers is not increased;

10) The cross-sectional area and thermal capacity of the hangers are not reduced;

11) Ceilings do not contain additional technical systems passing through or systems of larger dimensions than those tested;

12) No additional insulating layer is placed within the air cavity.

For test specimens where the fire separating property was tested, failure of these non-loadbearing protective components may lead to failure of individual loadbearing structural components. Protective components normally fail at some limiting condition dependent on the correlation between temperature and deflection. Because these correlations may change for a given element with support conditions, a caution should be expressed against using limiting temperatures for such an element, derived from restraint conditions, to support conditions which are more critical in deflection terms, that is, using a limiting temperature, achieved for a restrained element, for a simply-supported application and vice versa.

1) TCVN standards to be published