1、Designation: E73 83 (Reapproved 2007) E73 13Standard Practice forStatic Load Testing of Truss Assemblies1This standard is issued under the fixed designation E73; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revi
2、sion.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice is intended as a guide for use in the testing of truss assemblies fabricated from all types of constructionmaterials.
3、 While the practice may be used for the testing of a variety of assemblies, it is primarily intended to be used in the testingof 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 thetesting of wood residential trussed rafte
4、rs. Either proof tests or tests to destruction may be run.1.2 LimitationsIt 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 d
5、oes not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements, see
6、 Section 7.2. Referenced Documents2.1 ASTM Standards:2E196 Practice for Gravity Load Testing of Floors and Low Slope RoofsE575 Practice for Reporting Data from Structural Tests of Building Constructions, Elements, Connections, and AssembliesE631 Terminology of Building Constructions3. Terminology3.1
7、 trussa coplanar system of structural elements joined together at their ends usually to construct a series of triangles thatform a stable beam-like framework.3.2 static loada load or series of loads that are supported by or are applied to a structure so gradually that forces caused bychange in momen
8、tum of the load and structural elements can be neglected and all parts of the system at any instant are essentiallyin equilibrium.3.1 DefinitionsFor other definitions of terms in this practice, see Terminology E631.3.2 Definitions of Terms Specific to This Standard:3.2.1 truss, na coplanar system of
9、 structural elements joined together at their ends usually to construct a series of trianglesthat form a stable beam-like framework.3.2.2 static load, na load or series of loads that are supported by or are applied to a structure so gradually that forces causedby change in momentum of the load and s
10、tructural elements can be neglected and all parts of the system at any instant areessentially in equilibrium.4. Summary of Practice4.1 This practice outlines the procedures to be followed in the static load testing of major load carrying truss assemblies. Whilethe procedure tells what to do, it does
11、 not tell the testing agency how to do it.This leaves the selection of the test fixture and loadingmedium to the discretion of the testing agency. Materials selection, sampling, conditioning, fabrication, test procedures, and reportrequirements are covered.1 This practice is under the jurisdiction o
12、f ASTM Committee E06 on Performance of Buildings and is the direct responsibility of Subcommittee E06.11 on Horizontal andVertical Structures/Structural Performance of Completed Structures.Current edition approved April 1, 2007April 1, 2013. Published April 2007April 2013. Originally approved in 194
13、8. Last previous edition approved in 20022007 asE73 83 (2002).(2007). DOI: 10.1520/E0073-83R07.10.1520/E0073-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the s
14、tandards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accur
15、ately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Stat
16、es14.2 Two types of tests may be conducted using this practice:4.2.1 Proof TestsA proof test is frequently made to provide assurance that the truss will support a stated load or to determinethe deformations and structural response under a specified loading.4.2.2 Test to FailureIn testing to failure,
17、 more detailed information is generally desired such as ultimate load carryingcapacity, total load-deflection history, yield point, connection performance, factor of safety, etc.4.2.3 If desired, either type of test may be extended to include a determination of the magnitude and distribution of the
18、stressesin the members and connections in order to permit a more comprehensive analysis of the truss performance.5. Significance and Use5.1 This practice provides a guide to any individual, group, agency, or code body on the methods of test for truss assembliesfabricated from all types of constructi
19、on materials. Sample size is generally kept to a minimum to reduce costs. The methods maybe used to apply proof loads to an assembly or to test it to failure. Information obtained includes strength and stiffness data, andif assemblies are tested to their ultimate load carrying capacity, the failure
20、method or mechanism can be observed.6. Test Apparatus6.1 GeneralWhile the methods described in this procedure are best suited to tests of trusses before installation in a structure,they can also be applied to the testing of trusses after installation. In the former case, the truss may be tested in e
21、ither a verticalposition (normal or inverted) or in a horizontal position. Additional loadings must be applied to trusses tested in an inverted orhorizontal position to compensate for the effect of dead loads and gravity. Regardless of the orientation of the truss in the testfixture, the fixture and
22、 load application means shall be designed with an ample margin of safety to ensure that it is the test specimenthat is being tested and not the test fixture. More information on the testing of components in existing structures is contained inPractice E196.6.2 Supports and Reactions:6.2.1 The reactio
23、n supports shall provide sufficient clearance above the ground or restraint frame to allow for normaldisplacements, ease of loading, instrumentation, and provide room for observations and measurements. Supports shall haveadequate strength and stiffness to resist deformations during tests.6.2.2 Suppo
24、rt reaction hardware shall be typical of that planned for use in the completed structure or as required to satisfy theintent of the tests. In a single truss test, frequently the support at one end will allow rotation but not translation (a rocker) and theother will allow both rotation and translatio
25、n (a roller) so as not to induce additional unintentional secondary stresses into the testtruss as it deforms under load.6.2.3 Where lateral support is used, it shall not interfere with the free in-plane displacement of the truss assembly. The testtrusses shall not be laterally supported in a manner
26、 that will exceed that intended in a typical installation. Trusses tested in pairsshall be laterally braced and sheathed in a typical manner. Lateral bracing between trusses tested in pairs shall be installed in amanner to prevent both trusses from buckling together. Care shall be taken when testing
27、 trusses horizontally to keep the test trussflat to minimize any adverse lateral displacement caused by gravity.6.3 Loading Devices:6.3.1 The loading devices shall result in the desired truss loading situation regardless of whether uniform, concentrated, or acombination of both. The system shall be
28、such as to allow the application of loads during the test to approximate the overallintended in-service load distribution. Care should be taken to avoid eccentrically applied loads unless this type of loading isdesired.6.3.2 Vertical loads may be applied in the form of dead weight through bearing, s
29、uspension, or jacking arrangements. Horizontalloads are usually applied by some form of jacking arrangement directly in-plane or by using a system of cables and pulleys withdead weights or hydraulic cylinders. The loading system should have provisions for applying unbalanced loads when this type ofl
30、oading can be critical to truss performance (see 9.4). Uplift forces such as those caused by wind loads may be simulated byreversing the direction of the applied gravity loads; or if the fixture will permit it, testing the truss upside down. It is preferableto test the truss in its normally installe
31、d orientation in order to more typically allow for the uplift forces working against gravityforces.6.3.3 When loads are to be applied using dead weight, such items as sand, masonry units, iron or lead ingots, boxed nails, rollroofing, water or boxed fireplace logs have been successfully employed as
32、a loading medium. The arrangement of dead loadmaterial shall be such as to prevent any arching action that can seriously alter the intended load pattern. When water is used, careshall be taken to compartmentalize the water in cells to prevent a non-uniform load as the truss and elements deflect. Air
33、 bagsreacting against restraint frames have also been used.6.4 Load and Deflection Measuring Devices6.4.1 Load Measuring DevicesLoads may be measured using one or more of the following devices. Pressure gages orhydraulic load cells can be incorporated into a hydraulic loading system. These devices m
34、ust be calibrated with the jacks orcylinders at different positions of piston travel to ensure a true loading history. Spring dynamometers, electronic load cells, or theweighing tables of universal testing machines have also been successfully used. The load measuring device or devices used shallbe c
35、apable of measuring loads to an accuracy of 6 2 % 62 % of design load.E73 1326.4.2 Deflection Measuring Devices:6.4.2.1 Deflection readings may be taken in a variety of ways. One of the simplest methods is by the use of a taut wire ormono-filament line stretched between supports in combination with
36、a mirror-scale located at the desired deflection measuringpoints. Such a device avoids any magnification of deflection readings due to a settlement of supports during loading. When thetaut wire method is used, care must be taken to ensure that the wire will remain under tension during the entire tes
37、t. This can beaccomplished by incorporating a spring into the line or by letting one end run over a pulley with a weight attached to the line.Deflections are read on a scale with a mirror backing. The mirror-scale deflection measuring device is read by visually lining upthe top of the wire with its
38、image on the mirror and then reading the scale.6.4.2.2 Other commonly used devices are such things as direct reading micrometer dial gages, optical levels used to read scalesattached to the truss, linearly variable differential transformers (LVDT), or a combination of flexible wire attached at defle
39、ctionpoints and monitored remotely through a system of pulleys attached to dial gages. Deflection readings and measuring devices shallhave an accuracy of 6 2 % 62 % of design load deflection.6.4.3 Strain MeasurementsStrain measurements may be taken on truss elements using electrical or mechanical st
40、rain gages.Approximate stress distribution and magnitude may be observed by the application of special brittle lacquers to the areas ofinterest. All of these measurements should be made by personnel experienced in the application and operation of the methodsemployed on the material being tested.6.5
41、Typical SetupsSome suggested setups for running truss tests are shown in Figs. 1-3.7. Hazards7.1 Full-scale load tests of any large size specimen such as a truss can be hazardous to the individuals performing or observingthe tests, and also damage the testing fixtures or the structure housing the te
42、st setup due to a sudden release of stored energy atfailure. Care should be exercised in the preparation of the test setup to ensure that the failure of a test specimen will not result ina secondary collapse of a structural element not involved in the test.8. Test Specimens8.1 Number of SpecimensThe
43、 number of similar trusses that should be tested will vary with the desired precision andreliability of the information to be obtained and with the purpose of the text. Where only approximate values are desired or theassembly is large and contains many elements, a single test may suffice. Where more
44、 precise and statistically reliable data arerequired, a minimum of three or more tests are preferred. The final number will be controlled by the purpose of the tests, and asagreed upon by the sponsor, testing agency or regulatory agency, if any is involved.8.2 Materials:8.2.1 Truss assembly elements
45、, connectors, and connections shall be typical of those intended for use in the final product or asrequired to satisfy the intent of the tests.8.2.2 Truss materials that are moisture, time, temperature or otherwise sensitive to curing or conditioning, which can affect theperformance of the test asse
46、mbly, shall be representative of materials intended for use in the final assembly or as required to meetthe intent of the tests.8.3 Fabrication:8.3.1 Fabrication of the test specimens shall be typical of that intended for the finished product or as necessary to satisfy thepurpose of the tests. Where
47、 “standard” conditions are required at the time of test, such as a particular curing or aging time, moisturecontent, etc., the truss materials and the fabricated assemblies shall be conditioned, stored and handled in a manner to achieve them.8.3.2 Connections shall be made in accordance with good pr
48、actice following the recommendations of the manufacturer of theconnectors or connecting material involved.9. Loading Procedures9.1 Load Increments:9.1.1 Although the load increments may vary with the intent of the test, satisfactory load-response data can usually be obtainedif each of the first four
49、 increments of load does not exceed 25 % of the total design live load and any additional load incrementsdo not exceed 50 % of the design live load. Load shall be slowly applied to the truss assembly so as to provide a static loadingcondition. This is particularly important with materials that are sensitive to time under load.9.1.2 The above mentioned load increments apply to both uniform and concentrated loads.9.2 Deflection Measurements:9.2.1 As a minimum, take deflection measurements along the bottom chord at midspan and at quarter points.9.2.2 When deflection meas
