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Technical Note (National Research Council of Canada. Division of Building Research), 1958-10-01
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Fire Resistance Testing of Building Components
Hutcheon, N. B.; Shorter, G. W.
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NOT FOR PUBLICATION PREPARED BY
PREPARED FOR
N.B. Hutcheon and
G.W. Shorter CHECKED BY
General Distribution
FOR INTERNAL USE APPROVED BY
DATE October
1958
SUBJECT Fire Resistance Testing of Building Components
The Division of Building Research maintains a large
laboratory containing special furnaces for the exposure of large wall and floor panels to fire conditions simulating those in a building fire. These furnaces are used by the Fire Section of the Division of Building Research for research and testing but they can be made available also on a fee basis for the expooure of proprietary constructions including walls, floors, beams, and doors for which fire resistance ratings are required. This Note explains fire
re'sistance tests and how they are used, and describes the facilities available and the procedures to be followed in arranging for tests. Kinds of Fire Tests
Three main kinds of fire tests can be made in rating building materials and constructions. These are: combustibility tests, flame
spread tests, and fire resistance tests.
Combustibility tests are usually applied to determine to
what extent a material will burn when exposed to fire. They are used in rating materials for special purposes, usually in connection with building code work where it may be necessary to differentiate between materials that will burn and those that will not.
Flame spread tests measure the ability of a surface to support the spread of flame •. They are applied to materials used as the interior surfaces of a building to determine their influence on the rate at which fire is likely to spread, by surface burning, throughout the building.
The two tests already mentioned are sometimes regarded as measures of the resistance of materials to fire and are sometimes confused with fire resistance tests, with which this Note is
2
-building construotions such as beams and columns, to determine their ability to continue to function structurally during a fire and on wall, floor, and ceiling constructions to determine their ability to remain in place and to prevent a fire from spreading. Fire doors and other fire-resistive closures for openings are also rated on the same basis. The resistance of a construction is usually given in
terms of the time in hours during which it will perform satisfactorily under a standardized fire exposure.
Standard Conditions for Fire Resistance Tests
Fire resistance tests are usually carried out according to some recognized standardized procedure such as that given by ASTM ElI9-57, Standard Methods of Fire Tests of Building Construction and Materials, or by the corresponding British Standard BSI 476-1953, Fire Tests on Building Materials and Structures. The DBR wall and floor fUrnaces have been designed to provide for testing according to the U.S. standard but with some minor changes can also be used for ｴ･ｳｾｩｮｧ according to the British ｳｾ｡ｮ､｡ｲ､Ｎ
Building Codes and Bylaws
Fire resistanoe ratings are used in connection with building codes and building by-laws. These documents are concerned with the establishment of minimum standards of pUblic safety. The National Building Code of Canada (1953) which is used throughout Canada as a basis for many local building by-laws, calls for various grades of construction separations to be provided by constructions and closures having fire resistances appropriate to each grade. Appendix 4.l.B to the National Building Code lists results of fire resistance tests which have been conducted by various agencies in the United States. Constructions for which these or other acceptable fire resistance ratings are not available must be tested according to either
ASTM E119-57 or BSI 476-1953 for Code purposes.
Both of the above test procedures require that large representative samples of the various construotions be tested. The specifications for the furnace and the sample establish test conditions which simulate conditions in actual fires as far as possible, and at the same time, provide a uniform basis for
comparing results. Endurance periods are based on the behaviour of the sample with regard to various criteria of failure such as temperature rise on the unexposed surface; cracks or fissures whioh permit the passage of flame; and oollapse under load.
DBR Furnaoe Laboratory
The furnace laboratory is a part of the Fire Research
Building, located at the Montreal Road Laboratories of the National Research Council. It consists of a large room 125 by 40 by 40 ft high which houses two large furnaces, one for walls and the other for floors. Since the specimens to be tested are often both large and heavy, special facilities have been provided for construction on-site, and for curing and handling.
Handling of Heavy Materials
An outside paved area about 120 ft square provided along one side of the building carries a system of tracks on which steel trucks can be used for the storage or transport of panels and other equipment. There is an outdoor lifting frame 32 ft wide by 22 ft high, equipped with a 5-ton electric and a 24-ton hand-operated hoist, for loading and unloading trucks and ｴｲ｡ｮｳｾｯｲｴｳＮ The side of the laboratory is provided with a large door 18 ft wide and
24
ft high through which trucks or transports can be driven for unloading inside the laboratory by means of the 30-ton crane. Accommodation for ConstructionThe clear area provided within the laboratory is limited, but there is room for the construction of several wall panels at one time. It will seldom be possible to accommodate indoors more than ｯｾ･ floor panel under construction since they occupy such a large floor ｡ｲ･ｾＮ Much construction may have to be carried out on the outdoor paved area in summer.
Conditioning
The conditioning of samples prior to test, which involves mainly curing and drying, may be a long-term process especially in the case of heavy concrete sections. Exposure to fire while at a high moisture content may cause concrete to spall and may be an unduly severe test condition. Proper drying to a "normal" moisture content may take several months. There is accommodation for four floor panels in a conditioning area which, through controlled heating and ventilation, can be maintained at suitable conditions for drying.
Accommodation of Specimens in Furnaces
All specimens representative of portions of buildings 'that normally carry load must be loaded while exposed to fire during
4
-testing. Both the wall and the ·floor furnaces consist therefore of two main parts: a furnace having one open side into which a panel can be fitted, and a means of loading the panel during test. All floors normally carry load and so will in most cases be tested under load. Some walls are non-load-bearing and so need not be loaded during tests. Fire doors and other fire-resistant closures may be fitted into appropriate openings in special wall or floor panels and will usually not be loaded. Special arrangements may be made to support beams in the panel opening of the floor furnace, to block off the remaining panel area with suitable material, and to load the beam during test. Specimens are subjected to fire on one side only, simulating the case of a fire in a single room or space which is being confined by the enclosing construction. Firing of Furnaces
Both the wall and the floor furnace are fired with liquefied petroleum gas (propane) provided from a l750-gallon storage tank outside the building. There is an induced draft fan which draws off the fUrnace flue gases through a system of brick-lined flues and discharges them into a radial brick chimney. Draft at the furnaces is regulated automatically.
standard test methods call for firing to produce a speci-fied rise in temperature with time, usually to about l7000F at the
end of the first hour, with an increase of about 100°F per hour until the test is terminated. The fuel to the furnaces is auto-matically regulated to produce the prescribed time-temperature curve.
Wall Furnace Details
The wall furnace will accommodate a vertical panel up to 14 by 14 ft in the loading frame. Vertical loads can be applied by means of eight vertical jacks top and bottom, each capable of exerting a maximum load of 30,000 lb. The furnace which provides a clear opening for fire exposure of 12 by 12 ft is mounted on
rails and can be run up to the wall panel held in the loading frame. After a test the furnace can be run back for the application of a
hose stream to the hot side of the panel, a requirement of some tests. Wall panels to be tested may vary in size up to the
maximum of 14 by 14 ft. They may also be fitted into frames, or, if smaller than 12 by 12 ft, may be combined with additional
construction to bring them up to appropriate sizes for accommoda-tion in the loading frame and to fit them to the furnace opening so that a reasonably complete closure can be effected.
Constructions which are restrained laterally in use by adjacent construction may have to be restrained also during test. This may be done by ｢ｾｩｬ､ｩｮｧ the panel into a heavy restraining
frame or, in the DBR furnace, by additional horizontal jacks located along the vertical members of the loading frame, which can be
brought to bear on the vertical edges of the panel under test. Floor Furnace
The floor furnace consists essentially of a large box having an open top and sunk partially into the laboratory floor. It is heavily lined with fire brick, as is the wall furnace, and is
equipped with rows of burners firing horizontally inward from either side. The clear opening of the top of the furnace is 12 by 15 feet. The specimen to be tested must be fitted into a suitable frame, and
in some cases built in such a frame. The frame and specimen together can then be lifted to the top of the furnace by means of the 30-ton building crane, and when lowered into place form a closure, or lid, for the furnace which overlaps the test area of 12 by
15
ft and rests on the furnace walls. A second steel frame can then be lowered on to the main frame and fastened to it at four loading points. This loading frame carries a series of thirty vertical jacks which can be brought to bear and thus to apply loads vertically downward on the upper side of the test panel while it is exposed to fire on its under side. Each jack has a capacity of 3000 lb so that a simulated floor loading of 500 psf can be attained. Each jack is provided with a tripod head so that its load is applied through three points on the panel, thus providing one loading point on each 2 squarefeet of panel area, for a good approximation to uniform loading. Application for Testing
Anyone Wishing to have tests 'carried out should make
application for test work on a suitable form which may be obtained from, and when completed, should be returned to:
Administrative Officer,
Division of Building Research, National Research Council, Montreal Road Laboratories, Ottawa, Ont.
Testing will be carried out so far as possible in the order in which applications are accepted.
6 -Additional Information Required
It will be apparent from the foregoing description of fire resistance testing that these fire resistance tests are normally expensive and can have many complications which have to be resolved prior to actual testing. In most cases, it will be difficult to deal with all the many special problems involved by correspondence only. Discussions in person with members of the Fire Laboratory staff in Ottawa will usually be desirable. Matters which may have to be discussed prior to actual testing are:
1. Exact nature of the test required, which may include oonsiderationsof loading, restraint, hose stream, etc. 2. Design of the specimens, including any modifications
which may be necessary so that specimens can be fitted into the furnaces
3.
Arrangements for anyon-site construction or for provision of auxiliary components by the applicant4.
Conditioning, including curing and drying.Preparations for testing may have to be carried out-over many weeks or even months prior to actual testing. The longest periods will normally be required in the case of heavy wall and floor constructions involving heavy concrete sections which may have to be constructed on the site and then suitably conditioned. Factory-made items such as fire doors, metal panels, precast
sections, etc., for which adapting constructions are already available, will require relatively little preparation time.
All inquiries related to the technical aspects of tests should be directed to:
G. W. Shorter,
Fire Research Laboratory, National Research Council, Montreal Road Laboratories, Ottawa, Ont.
Costs
It is the policy of the National Research Council to establish appropriate fixed charges for "standard" tests, when there has been sufficient experience on which to base suitable charges. In view of the nature of fire resistance tests, it will
not usually be possible to establish costs accurately in advance, and charges will have to be based on staff time and materials used, plus the usual allowance for overhead. The best possible
advance estimate of cost will always be made by DBR staff when the character and extent of any specific fire resistance·test are known.
