ASTM E73-83(1996)e1
(Practice)Standard Practice for Static Load Testing of Truss Assemblies
Standard Practice for Static Load Testing of Truss Assemblies
SCOPE
1.1 This practice is intended as a guide for use in the testing of truss assemblies fabricated from all types of construction materials. While the practice may be used for the testing of a variety of assemblies, it is primarily intended to be used in the testing of those trusses designed to be spaced at 1.2 m (48 in.) centers or greater. It can be used, but it is not normally intended, for the testing of wood residential trussed rafters. Either proof tests or tests to destruction may be run.
1.2 Limitations -It is not intended that this practice be used for routine quality control testing.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 6.
General Information
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Standards Content (Sample)
e1
Designation: E 73 – 83 (Reapproved 1996) An American National Standard
Standard Practice for
Static Load Testing of Truss Assemblies
This standard is issued under the fixed designation E 73; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Keywords were added editorially in March 1996.
1. Scope 3.3 For other definitions in this practice, see Terminology
E 631.
1.1 This practice is intended as a guide for use in the testing
of truss assemblies fabricated from all types of construction
4. Summary of Practice
materials. While the practice may be used for the testing of a
4.1 This practice outlines the procedures to be followed in
variety of assemblies, it is primarily intended to be used in the
the static load testing of major load carrying truss assemblies.
testing of those trusses designed to be spaced at 1.2 m (48 in.)
While the procedure tells what to do, it does not tell the testing
centers or greater. It can be used, but it is not normally
agency how to do it. This leaves the selection of the test fixture
intended, for the testing of wood residential trussed rafters.
and loading medium to the discretion of the testing agency.
Either proof tests or tests to destruction may be run.
Materials selection, sampling, conditioning, fabrication, test
1.2 Limitations—It is not intended that this practice be used
procedures, and report requirements are covered.
for routine quality control testing.
4.2 Two types of tests may be conducted using this practice:
1.3 This standard does not purport to address all of the
4.2.1 Proof Tests—A proof test is frequently made to
safety concerns, if any, associated with its use. It is the
provide assurance that the truss will support a stated load or to
responsibility of the user of this standard to establish appro-
determine the deformations and structural response under a
priate safety and health practices and determine the applica-
specified loading.
bility of regulatory limitations prior to use. For specific hazard
4.2.2 Test to Failure—In testing to failure, more detailed
statements, see Section 7.
information is generally desired such as ultimate load carrying
2. Referenced Documents capacity, total load-deflection history, yield point, connection
performance, factor of safety, etc.
2.1 ASTM Standards:
4.2.3 If desired, either type of test may be extended to
E 196 Practice for Gravity Load Testing of Floors And Flat
include a determination of the magnitude and distribution of
Roofs
the stresses in the members and connections in order to permit
E 575 Practice for Reporting Data from Structural Tests of
a more comprehensive analysis of the truss performance.
Building Constructions, Elements, Connections, and As-
semblies
5. Significance and Use
E 631 Terminology of Building Constructions
5.1 This practice provides a guide to any individual, group,
3. Terminology agency, or code body on the methods of test for truss
assemblies fabricated from all types of construction materials.
3.1 truss—a coplanar system of structural elements joined
Sample size is generally kept to a minimum to reduce costs.
together at their ends usually to construct a series of triangles
The methods may be used to apply proof loads to an assembly
that form a stable beam-like framework.
or to test it to failure. Information obtained includes strength
3.2 static load—a load or series of loads that are supported
and stiffness data, and if assemblies are tested to their ultimate
by or are applied to a structure so gradually that forces caused
load carrying capacity, the failure method or mechanism can be
by change in momentum of the load and structural elements
observed.
can be neglected and all parts of the system at any instant are
essentially in equilibrium.
6. Test Apparatus
6.1 General—While the methods described in this proce-
This practice is under the jurisdiction of ASTM Committee E-6 on Performance dure are best suited to tests of trusses before installation in a
of Buildings and is the direct responsibility of Subcommittee E06.11 on Horizontal
structure, they can also be applied to the testing of trusses after
and Vertical Structures/Structural Performance of Completed Structures.
installation. In the former case, the truss may be tested in either
Current edition approved March 10, 1996. Published May 1996. Originally
a vertical position (normal or inverted) or in a horizontal
published as E 73 – 48 T. Last previous edition E 73 - 83 (1991).
Annual Book of ASTM Standards, Vol 04.11.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E73
position. Additional loadings must be applied to trusses tested can seriously alter the intended load pattern. When water is
in an inverted or horizontal position to compensate for the used, care shall be taken to compartmentalize the water in cells
effect of dead loads and gravity. Regardless of the orientation
to prevent a non-uniform load as the truss and elements deflect.
of the truss in the test fixture, the fixture and load application Air bags reacting against restraint frames have also been used.
means shall be designed with an ample margin of safety to
6.4 Load and Deflection Measuring Devices
ensure that it is the test specimen that is being tested and not
6.4.1 Load Measuring Devices—Loads may be measured
the test fixture. More information on the testing of components
using one or more of the following devices. Pressure gages or
in existing structures is contained in Practice E 196.
hydraulic load cells can be incorporated into a hydraulic
6.2 Supports and Reactions:
loading system. These devices must be calibrated with the
6.2.1 The reaction supports shall provide sufficient clear-
jacks or cylinders at different positions of piston travel to
ance above the ground or restraint frame to allow for normal
ensure a true loading history. Spring dynamometers, electronic
displacements, ease of loading, instrumentation, and provide
load cells, or the weighing tables of universal testing machines
room for observations and measurements. Supports shall have
have also been successfully used. The load measuring device or
adequate strength and stiffness to resist deformations during
devices used shall be capable of measuring loads to an
tests.
accuracy of 6 2 % of design load.
6.2.2 Support reaction hardware shall be typical of that
6.4.2 Deflection Measuring Devices:
planned for use in the completed structure or as required to
6.4.2.1 Deflection readings may be taken in a variety of
satisfy the intent of the tests. In a single truss test, frequently
ways. One of the simplest methods is by the use of a taut wire
the support at one end will allow rotation but not translation (a
or mono-filament line stretched between supports in combina-
rocker) and the other will allow both rotation and translation (a
tion with a mirror-scale located at the desired deflection
roller) so as not to induce additional unintentional secondary
measuring points. Such a device avoids any magnification of
stresses into the test truss as it deforms under load.
deflection readings due to a settlement of supports during
6.2.3 Where lateral support is used, it shall not interfere
loading. When the taut wire method is used, care must be taken
with the free in-plane displacement of the truss assembly. The
to ensure that the wire will remain under tension during the
test trusses shall not be laterally supported in a manner that will
entire test. This can be accomplished by incorporating a spring
exceed that intended in a typical installation. Trusses tested in
into the line or by letting one end run over a pulley with a
pairs shall be laterally braced and sheathed in a typical manner.
weight attached to the line. Deflections are read on a scale with
Lateral bracing between trusses tested in pairs shall be installed
a mirror backing. The mirror-scale deflection measuring device
in a manner to prevent both trusses from buckling together.
is read by visually lining up the top of the wire with its image
Care shall be taken when testing trusses horizontally to keep
on the mirror and then reading the scale.
the test truss flat to minimize any adverse lateral displacement
6.4.2.2 Other commonly used devices are such things as
caused by gravity.
direct reading micrometer dial gages, optical levels used to
6.3 Loading Devices:
read scales attached to the truss, linearly variable differential
6.3.1 The loading devices shall result in the desired truss
transformers (LVDT), or a combination of flexible wire at-
loading situation regardless of whether uniform, concentrated,
tached at deflection points and monitored remotely through a
or a combination of both. The system shall be such as to allow
system of pulleys attached to dial gages. Deflection readings
the application of loads during the test to approximate the
and measuring devices shall have an accuracy of 6 2% of
overall intended in-service load distribution. Care should be
design load deflection.
taken to avoid eccentrically applied loads unless this type of
6.4.3 Strain Measurements—Strain measurements may be
loading is desired.
taken on truss elements using electrical or mechanical strain
6.3.2 Vertical loads may be applied in the form of dead
gages. Approximate stress distribution and magnitude may be
weight through bearing, suspension, or jacking arrangements.
observed by the application of special brittle lacquers to the
Horizontal loads are usually applied by some form of jacking
areas of interest. All of these measurements should be made by
arrangement directly in-plane or by using a system of cables
personnel experienced in the application and operation of the
and pulleys with dead weights or hydraulic cylinders. The
methods employed on the material being tested.
loading system should have provisions for applying unbal-
6.5 Typical Setups—Some suggested setups for running
anced loads when this type of loading can be critical to truss
truss tests are shown in Figs. 1-3.
performance (see 9.4). Uplift forces such as those caused by
wind loads may be simulated by reversing the direction of the
7. Hazards
applied gravity loads; or if the fixture will permit it, testing the
truss upside down. It is preferable to test the truss in its
7.1 Full-scale load tests of any large size specimen such as
normally installed orientation in order to more typically allow
a truss can be hazardous to the individuals performing or
for the uplift forces working against gravity forces.
observing the tests, and also damage the
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