1、Designation: C1824 161Standard Test Method forFull Scale Bending Test of Spun Prestressed ConcreteBases for Tapered Steel Lighting Poles1This standard is issued under the fixed designation C1824; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were made in March 2016.1. Scope1.1 This test method covers determination of ultim
3、ate bend-ing moment capacity and cracking moment capacity of con-crete bases used as foundations for tapered steel lighting polesin accordance to Specification C1804.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions t
4、o SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and de
5、termine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C39 Test Method for Compressive Strength of CylindricalConcrete SpecimensC192 Practice for Making and Curing Concrete Test Speci-mens in the LaboratoryC1804 Specification for Spun Cast Prestre
6、ssed ConcreteBases for Tapered Steel Lighting Poles3. Terminology3.1 Definitions:3.1.1 cracking loada load which creates a bending mo-ment of enough magnitude to produce a tensile stress greaterthan the sum of induced compression plus the tensile strengthof the concrete resulting in tensile cracks o
7、n the tension face ofthe base.3.1.2 cylindrical sectionlower portion of base designed tobe buried in concrete backfill below ground line.3.1.3 ground lineis the distance from the butt end of thebase to the point where theoretical embedment in the founda-tion is specified (theoretical buried depth).3
8、.1.4 second crack (re-cracking) loadthe load at which apreviously formed crack will reopen.3.1.5 spun basea base in which the concrete is distributedand compacted through centrifugal force.3.1.6 tapered sectionupper portion of base, which has ataper designed to match overlapping steel pole taper.3.1
9、.7 ultimate loadmaximum test load the base will carryin the specified direction before the steel or concrete will reachits limiting state.4. Summary of Test Method4.1 This test consists of applying transverse loads at apredetermined distance to simulate bending moments inducedby wind forces exerted
10、on the spun concrete base. The base istested in a horizontal orientation. The concrete base specimenis laterally supported at two locations: at the ground line andnear the bottom end of the base. The bending load is appliedthrough a steel test arm consisting of a matching taper steeladaptor with app
11、ropriate extension, which is of sufficientlength to deem shear effects negligible. Bending loads areapplied gradually at a predetermined loading sequence. Thetest bending moment is determined by multiplying the momentarm measured from the simulated ground line to the loadapplication point multiplied
12、 by the applied load value. Due tothe relatively short height of these bases extending aboveground line in comparison to the entire structure height,obtaining deflection data is not required.5. Significance and Use5.1 This test method is intended to provide the user withacceptable apparatus requirem
13、ents and a prescribed procedureto determine the bending moment capacity of spun pre-stressedconcrete bases for use with tapered steel poles.5.2 The results of this test method are used as a basis forverification of calculated bending moment capacity, qualitycontrol tool for manufacturing process and
14、 as a basis fordetermining statistical bending moment capacity.1This test method is under the jurisdiction of ASTM Committee C27 on PrecastConcrete Products and is the direct responsibility of Subcommittee C27.20 onArchitectural and Structural Products.Current edition approved Jan. 1, 2016. Publishe
15、d January 2016. DOI: 10.1520/C182416E01.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.3 This test method shall not be used for full lengthprestressed concrete, steel, or composite poles.6. Apparatus6.1 General RequirementsThe test
16、 area, fixtures and adap-tors shall be sized to accommodate the largest test specimenswith adequate margin to include upper tolerances of testspecimens. The general layout shall allow for application oftransverse loads in direction perpendicular to the centerline oftest specimen (see Fig. 1).6.2 Loa
17、ding ApparatusThe loading apparatus consists ofa winch and a steel cable through which the load is applied tothe test arm. The winch machine shall be capable of applyingloads that are required to test the bases to failure. The loadingapparatus shall be capable of applying the required loadingsequenc
18、e in continuous manner. The loading apparatus shall becapable of starting and stopping force application under load,as well as, it shall be capable of maintaining a static load at anypoint during the test sequence.6.3 Test ArmThe test arm shall consist of tapered steeladaptor and extension. The insi
19、de diameter and taper of theadaptor shall match the outside diameter and taper of the testspecimen. The extension shall be long enough to allow for aload application point with a moment arm that will ensure thatthe base primary mode of failure is in flexure with negligibleshear effects. The test arm
20、 shall be supported by rollingsupports to eliminate the effects of gravity loading in thevertical direction perpendicular to the test plane due to theweight of the test arm.6.4 Load CellThe load cell shall have a capacity greaterthan the load necessary to test the bases to failure. Resolutionof the
21、load cell shall be smaller than 10 lb or 1 % of theultimate load whichever is greater. The load cell shall beattached to the moment arm extension. The load cell and loadcell controller shall have current calibration certificate. Cali-bration shall be performed annually.6.5 Fixturing of Test Specimen
22、The test specimen shall belaterally supported at the two reaction points by rigid fixturingbrackets with contact area large enough, at least 20 % of thebase circumference by 8 in. (200 mm) length, to avoid damagedue to stress concentration. The fixturing brackets shall belined with elastomeric mater
23、ial (Neoprene or SBR sheetrubber) at least12 in. (12.5 mm) thick and minimum 70durometer hardness. Alternatively, seasoned oak at least 4 in.(100 mm) thick can be used as a lining material. The distancebetween the reaction points (center to center of supports) shallnot be less than 5.5 ft (1680 mm)
24、to minimize the shear effectsat ground line section. The designed ground line location shallbe aligned with the edge of support bracket on the loading side.The bottom end of the test specimen shall extend at least 18 in.from the bottom support bracket7. Setup Tolerances7.1 The test specimen centerli
25、ne, extension arm centerlineand loading cable shall be located within 2 in. (50 mm) oftheoretical test plane.7.2 The designed test specimen ground line shall be alignedwith the edge of ground line support bracket within 1 in. (25mm).7.3 The initial load application direction shall be perpen-dicular
26、to the test specimen centerline within five degrees.7.4 Test arm adaptor taper and diameter shall be withindesign tolerances of matching steel pole shaft.7.5 Test arm adaptor engagement with the test specimenshall be within tolerance range of designed base to poleoverlap.FIG. 1 Horizontal Bending Te
27、st DiagramC1824 16128. Load Measurement8.1 Load shall be measured by a suitable measuring deviceplaced in series in the pulling line. The recommended methodis a calibrated metal tension bar fitted with calibrated electric-type strain gages, that is, load cell, suitably wrapped or housedfor protectio
28、n against shock when the base breaks. This methodpermits remote reading of loads and minimizes the possibilityof personal injury during test. Alternatively, where electric-type strain gaging equipment is not available, load may bemeasured by a dynamometer of suitable capacity, graduated in50 lb (200
29、 N) divisions, maximum increments of 1 % of therated capacity. Calibration of the dynamometer shall bechecked annually as a minimum at frequent intervals during thetests. A dynamometer is not recommended unless the personreading the data can be protected from inadvertent failure ofthe pulling line o
30、r tackle.9. Test Specimens9.1 The test specimens shall be manufactured in accordancewith standard manufacturing process in accordance with Speci-fication C1804.9.2 Size and feature dimensions of the test specimens shallbe within design tolerances.9.3 Any damage deemed cosmetic shall be reviewed by a
31、structural engineer prior to testing. Test specimens with dam-age severe enough to affect structural performance shall not beused for testing.9.4 Test specimens used for quality control tool for manu-facturing process, for design verification, or as a basis fordetermining statistical bending moment
32、capacity shall beselected randomly and tested at ages between 28 days and 35days from their manufacturing date.9.5 Bases may also be tested before 28 days or after 35 daysfor purposes other than specified in 9.4.9.6 Base test specimens shall be accompanied by concretecylinder specimens prepared in a
33、ccordance with Practice C192at base manufacturing time. The concrete cylinder specimensshall be tested in accordance with Test Method C39 at strandrelease time and at 28 days of age.10. Procedure10.1 Setup and secure the test specimen in the test apparatusin accordance with Sections 4, 6, 7, and 8 o
34、f this standard.10.2 To determine cracking load apply load and recordactual load values in the following sequence:10.2.1 Apply load in increments of 10 to 20 % of thecalculated ultimate load up to 90 % of calculated cracking load.10.2.2 Apply additional load in smaller increments on theorder of 1 %
35、to 5 % of calculated ultimate load. Hold the loadafter each increment and look for visible crack on the tensionside of the test specimen. Record the load value (cracking load)at which the first crack occurred.10.2.3 Release the load.10.3 To determine zero tension moment and ultimate bend-ing moment
36、capacity apply load and record actual load valuesin the following sequence:10.3.1 Apply load in increments of 10 to 20 % of thecalculated ultimate load up to 70 % of calculated cracking load.10.3.2 Apply additional load in smaller increments on theorder of 1 % to 5 % of calculated ultimate load. Hol
37、d the loadafter each increment and look for visible crack on the tensionside of the test specimen. Record the load value (second crackload) at which the first crack reopened.10.3.3 Increase load to 75 % of the calculated ultimate loadand hold for 3 minutes.10.3.4 Increase load to 90 % of the calcula
38、ted ultimate loadand hold for 3 minutes.10.3.5 Increase load to 100 % of the calculated ultimateload and hold for 3 minutes.10.3.6 Continue loading until the base fails. Record the peakload (ultimate load).11. Determination of Test Moments11.1 Test moment values for first cracking moment, secondcrac
39、k (zero tension moment), and ultimate bending momentshall be determined according to the following formula:M 5 L*P1000 (1)where:M = the moment, ft-kip (Nm),L = moment arm, ft (m), measured from ground line to loadattachment point, andP = recorded test load corresponding to the first crack,second cra
40、ck (zero tension), and ultimate loadrespectively, lb (N).12. Report12.1 Report shall include the following information:12.1.1 Test date.12.1.2 Test specimen production date.12.1.3 Age of test specimen at time of testing, in days.12.1.4 Base description, size or part number.12.1.5 Base geometry, incl
41、uding diameter at ground line.12.1.6 Taper adaptor overlap.12.1.7 Moment arm length measured from ground line.12.1.8 Calculated first cracking moment.12.1.9 Calculated second crack (zero tension) moment.12.1.10 Calculated ultimate moment.12.1.11 Test first cracking moment.12.1.12 Test second crack (
42、zero tension) moment.12.1.13 Test ultimate moment.12.1.14 Type of failure and location.12.1.15 Concrete cylinder compressive strength data at thefollowing ages: 28 days, prestress release, and at day of test.12.2 Report may include the following supplementaryinformation, if available:12.2.1 Photogra
43、phs of cracks on tension side showinglocation of first crack.12.2.2 Photographs of failure area showing location andsize of failure region.12.2.3 Photographs of cores taken above and below thefailure area showing core dimensions.12.2.4 Measurement of strand slip at the tip end of the base.C1824 1613
44、13. Precision and Bias13.1 The precision and bias of the test procedures are beingdetermined and will be provided when sufficient data areavailable to indicate acceptable tolerances in repeatability andreproducibility.14. Keywords14.1 bending test; cracking moment; prestressed concrete;spun base; st
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