ASTM E73-13(2021)
(Practice)Standard Practice for Static Load Testing of Truss Assemblies
Standard Practice for Static Load Testing of Truss Assemblies
SIGNIFICANCE AND USE
5.1 This practice provides a guide to any individual, group, agency, or code body on the methods of test for truss assemblies fabricated from all types of construction materials. Sample size is generally kept to a minimum to reduce costs. The methods may be used to apply proof loads to an assembly or to test it to failure. Information obtained includes strength and stiffness data, and if assemblies are tested to their ultimate load carrying capacity, the failure method or mechanism can be observed.
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 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 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E73 − 13 (Reapproved 2021)
Standard Practice for
Static Load Testing of Truss Assemblies
This standard is issued under the fixed designation E73; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E631 Terminology of Building Constructions
1.1 This practice is intended as a guide for use in the testing
3. Terminology
of truss assemblies fabricated from all types of construction
3.1 Definitions—For definitions of terms in this practice, see
materials. While the practice may be used for the testing of a
Terminology E631.
variety of assemblies, it is primarily intended to be used in the
testing of those trusses designed to be spaced at 1.2 m centers
3.2 Definitions of Terms Specific to This Standard:
orgreater.Itcanbeused,butitisnotnormallyintended,forthe
3.2.1 truss, n—a coplanar system of structural elements
testing of wood residential trussed rafters. Either proof tests or
joined together at their ends usually to construct a series of
tests to destruction may be run.
triangles that form a stable beam-like framework.
1.2 Limitations—It is not intended that this practice be used
3.2.2 static load, n—a load or series of loads that are
for routine quality control testing. supported by or are applied to a structure so gradually that
forces caused by change in momentum of the load and
1.3 The values stated in SI units are to be regarded as
structural elements can be neglected and all parts of the system
standard. No other units of measurement are included in this
at any instant are essentially in equilibrium.
standard.
1.4 This standard does not purport to address all of the
4. Summary of Practice
safety concerns, if any, associated with its use. It is the
4.1 This practice outlines the procedures to be followed in
responsibility of the user of this standard to establish appro-
the static load testing of major load carrying truss assemblies.
priate safety, health, and environmental practices and deter-
While the procedure tells what to do, it does not tell the testing
mine the applicability of regulatory limitations prior to use.
agency how to do it.This leaves the selection of the test fixture
For specific hazard statements, see Section 7.
and loading medium to the discretion of the testing agency.
1.5 This international standard was developed in accor-
Materials selection, sampling, conditioning, fabrication, test
dance with internationally recognized principles on standard-
procedures, and report requirements are covered.
ization established in the Decision on Principles for the
4.2 Two types of tests may be conducted using this practice:
Development of International Standards, Guides and Recom-
4.2.1 Proof Tests—A proof test is frequently made to pro-
mendations issued by the World Trade Organization Technical
vide assurance that the truss will support a stated load or to
Barriers to Trade (TBT) Committee.
determine the deformations and structural response under a
2. Referenced Documents
specified loading.
2.1 ASTM Standards: 4.2.2 Test to Failure—In testing to failure, more detailed
E196 Practice for Gravity Load Testing of Floors and Low information is generally desired such as ultimate load carrying
Slope Roofs capacity, total load-deflection history, yield point, connection
E575 Practice for Reporting Data from Structural Tests of performance, factor of safety, etc.
Building Constructions, Elements, Connections, and As- 4.2.3 If desired, either type of test may be extended to
include a determination of the magnitude and distribution of
semblies
the stresses in the members and connections in order to permit
a more comprehensive analysis of the truss performance.
This practice is under the jurisdiction of ASTM Committee E06 on Perfor-
mance of Buildings and is the direct responsibility of Subcommittee E06.11 on
Horizontal and Vertical Structures/Structural Performance of Completed Structures.
5. Significance and Use
Current edition approved Oct. 1, 2021. Published October 2021. Originally
5.1 This practice provides a guide to any individual, group,
approved in 1948. Last previous edition approved in 2013 as E73 – 13. DOI:
10.1520/E0073-13R21.
agency, or code body on the methods of test for truss
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
assemblies fabricated from all types of construction materials.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Sample size is generally kept to a minimum to reduce costs.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. The methods may be used to apply proof loads to an assembly
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E73 − 13 (2021)
or to test it to failure. Information obtained includes strength performance (see 9.4). Uplift forces such as those caused by
and stiffness data, and if assemblies are tested to their ultimate wind loads may be simulated by reversing the direction of the
loadcarryingcapacity,thefailuremethodormechanismcanbe applied gravity loads; or if the fixture will permit it, testing the
observed. truss upside down. It is preferable to test the truss in its
normally installed orientation in order to more typically allow
6. Test Apparatus
for the uplift forces working against gravity forces.
6.3.3 When loads are to be applied using dead weight, such
6.1 General—While the methods described in this proce-
items as sand, masonry units, iron or lead ingots, boxed nails,
dure are best suited to tests of trusses before installation in a
roll roofing, water or boxed fireplace logs have been success-
structure, they can also be applied to the testing of trusses after
fully employed as a loading medium. The arrangement of dead
installation. In the former case, the truss may be tested in either
loadmaterialshallbesuchastopreventanyarchingactionthat
a vertical position (normal or inverted) or in a horizontal
can seriously alter the intended load pattern. When water is
position. Additional loadings must be applied to trusses tested
used, care shall be taken to compartmentalize the water in cells
in an inverted or horizontal position to compensate for the
topreventanon-uniformloadasthetrussandelementsdeflect.
effect of dead loads and gravity. Regardless of the orientation
Air bags reacting against restraint frames have also been used.
of the truss in the test fixture, the fixture and load application
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 E196.
hydraulic load cells can be incorporated into a hydraulic
loading system. These devices must be calibrated with the
6.2 Supports and Reactions:
jacks or cylinders at different positions of piston travel to
6.2.1 The reaction supports shall provide sufficient clear-
ensure a true loading history. Spring dynamometers, electronic
ance above the ground or restraint frame to allow for normal
load cells, or the weighing tables of universal testing machines
displacements, ease of loading, instrumentation, and provide
havealsobeensuccessfullyused.Theloadmeasuringdeviceor
room for observations and measurements. Supports shall have
devices used shall be capable of measuring loads to an
adequate strength and stiffness to resist deformations during
accuracy of 62 % of design load.
tests.
6.4.2 Deflection Measuring Devices:
6.2.2 Support reaction hardware shall be typical of that
6.4.2.1 Deflection readings may be taken in a variety of
planned for use in the completed structure or as required to
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
or mono-filament line stretched between supports in combina-
the support at one end will allow rotation but not translation (a
rocker) and the other will allow both rotation and translation (a tion with a mirror-scale located at the desired deflection
measuring points. Such a device avoids any magnification of
roller) so as not to induce additional unintentional secondary
stresses into the test truss as it deforms under load. deflection readings due to a settlement of supports during
loading.When the taut wire method is used, care must be taken
6.2.3 Where lateral support is used, it shall not interfere
to ensure that the wire will remain under tension during the
with the free in-plane displacement of the truss assembly. The
entire test. This can be accomplished by incorporating a spring
testtrussesshallnotbelaterallysupportedinamannerthatwill
into the line or by letting one end run over a pulley with a
exceed that intended in a typical installation. Trusses tested in
weight attached to the line. Deflections are read on a scale with
pairs shall be laterally braced and sheathed in a typical manner.
a mirror backing.The mirror-scale deflection measuring device
Lateralbracingbetweentrussestestedinpairsshallbeinstalled
is read by visually lining up the top of the wire with its image
in a manner to prevent both trusses from buckling together.
on the mirror and then reading the scale.
Care shall be taken when testing trusses horizontally to keep
the test truss flat to minimize any adverse lateral displacement 6.4.2.2 Other commonly used devices are such things as
direct reading micrometer dial gages, optical levels used to
caused by gravity.
read scales attached to the truss, linearly variable differential
6.3 Loading Devices:
transformers (LVDT), or a combination of flexible wire at-
6.3.1 The loading devices shall result in the desired truss
tached at deflection points and monitored remotely through a
loading situation regardless of whether uniform, concentrated,
system of pulleys attached to dial gages. Deflection readings
or a combination of both. The system shall be such as to allow
and measuring devices shall have an accuracy of 62% of
the application of loads during the test to approximate the
design load deflection.
overall intended in-service load distribution. Care should be
6.4.3 Strain Measurements—Strain measurements may be
taken to avoid eccentrically applied loads unless this type of
taken on truss elements using electrical or mechanical strain
loading is desired.
gages. Approximate stress distribution and magnitude may be
6.3.2 Vertical loads may be applied in the form of dead
observed by the application of special brittle lacquers to the
weight through bearing, suspension, or jacking arrangements.
areas of interest.All of these measurements should be made by
Horizontal loads are usually applied by some form of jacking
personnel experienced in the application and operation of the
arrangement directly in-plane or by using a system of cables
methods employed on the material being tested.
and pulleys with dead weights or hydraulic cylinders. The
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.
E73 − 13 (2021)
(a) Truss assembly with panel point loading.
(b) Truss assembly with chord loading.
FIG. 1 Trusses Set Vertical, in Normal Position
FIG. 2 Truss Set Vertical, in Inverted Position
7. Hazards specimen will not result in a secondary collapse of a structural
element not involved in the test.
7.1 Full-scale load tests of any large size specimen such as
a truss can be hazardous to the individuals performing or
8. Test Specimens
observing the tests, and also damage the testing fixtures or the
structure housing the test setup due to a sudden release of 8.1 Number of Specimens—The number of similar trusses
stored energy at failure. Care should be exercised in the that should be tested will vary with the desired precision and
preparation of the test setup to ensure that the failure of a test reliability of the information to be obtained and with the
E73 − 13 (2021)
FIG. 3 Truss in Vertical Position
purpose of the test.Where only approximate values are desired provide a static loading condition. This is particularly impor-
or the assembly is large and contains many elements, a single tant with materials that are sensitive to time under load.
test may suffice. Where more precise and statistically reliable
9.1.2 The above mentioned load increments apply to both
data are required, a minimum of three or more tests are
uniform and concentrated loads.
preferred. The final number will be controlled by the purpose
9.2 Deflection Measurements:
of the tests, and as agreed upon by the sponsor, testing agency
9.2.1 As a minimum, take deflection measurements along
or regulatory agency, if any is involved.
the bottom chord at midspan and at quarter points.
8.2 Materials:
9.2.2 When deflection measuring systems that do not com-
8.2.1 Truss assembly elements, connectors, and connections
pensate for support settlement are used, measurement of
shall be typical of those intended for use in the final product or
support displacement under load is needed to obtain an
as required to satisfy the intent of the tests.
accurate load-deflection response and recovery after the re-
8.2.2 Truss materials that are moisture, time, temperature or
moval of load.
otherwise sensitive to curing or conditioning, which can affect
the performance of the test assembly, shall be representative of
9.3 Duration of Load Application—Except in the instances
materials intended for use in the final assembly or as required
of impact and racking tests, after each increment of load is
to meet the intent of the tests.
applied, the load level shall be maintained as constant as
possible for a period of 5 min (see 9.3.1). Deformation
8.3 Fabrication:
readings shall be taken as soon as practical after load
8.3.1 Fabrication of the test specimens shall be typical of
application, at the end of the 5 min period under constant load,
that intended for the finished product or as necessary to satisfy
and immediately and at the end of the 5 min period after any
the purpose of the tests.
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