1、Designation: C1824 16Standard 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 o
2、f 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.1. Scope1.1 This test method covers determination of ultimate bend-ing moment capacity and cracking moment
3、 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 to SI units that are provided for information onl
4、yand 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 determine the applica-bility of regulatory limitat
5、ions 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 Prestressed ConcreteBases for Tapered Steel Lighting Po
6、les3. 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 on the tension face ofthe base.3.1.2 cylindrical
7、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).3.1.4 second crack (re-cracking) loadthe load at
8、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.3.1.7 ultimate loadmaximum test load the base will
9、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 on the spun concrete base. The base istested in
10、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 appropriate extension, which is of sufficientlength
11、 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 by the applied load value. Due tothe relatively
12、 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 requirements and a prescribed procedureto determine the
13、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 as a basis fordetermining statistical bending m
14、oment capacity.5.3 This test method shall not be used for full lengthprestressed concrete, steel, or composite poles.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 Pr
15、oducts.Current edition approved Jan. 1, 2016. Published January 2016. DOI: 10.1520/C182416.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Apparatus6.1 General RequirementsThe test area, fixtures and adap-tors shall be sized to acc
16、ommodate 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 Loading ApparatusThe loading apparatus consists ofa wi
17、nch and a steel cable through which the load is applied tothe test arm. The winch machine shall be capable of threeapplying loads that are required to test the bases to failure. Theloading apparatus shall be capable of applying the requiredloading sequence in continuous manner. The loading apparatus
18、shall be capable of starting and stopping force applicationunder load, as well as, it shall be capable of maintaining a staticload at any point during the test sequence.6.3 Test ArmThe test arm shall consist of tapered steeladaptor and extension. The inside diameter and taper of theadaptor shall mat
19、ch 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 shall be supported by rollingsupports to eli
20、minate 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 load cell shall be smaller than 10 lb or 1 %
21、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 SpecimenThe test specimen shall belaterally supported
22、 at the two reaction points by rigid fixturingbrackets with contact area large enough, at least 20 percent ofthe base circumference by 8 in. (200 mm) length, to avoiddamage due to stress concentration. The fixturing bracketsshall be lined with elastomeric material (Neoprene or SBRsheet rubber) at le
23、ast12 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) to minimize the shear effectsat ground
24、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 centerline, extension arm centerlineand loading
25、 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 to the test specimen centerline within
26、five degrees.7.4 Test arm adaptor taper and diameter shall be withindesign tolerances of matching steel pole shaft.FIG. 1 Horizontal Bending Test DiagramC1824 1627.5 Test arm adaptor engagement with the test specimenshall be within tolerance range of designed base to poleoverlap.8. Load Measurement8
27、.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 protection against shock when the base breaks. Th
28、is 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 N) divisions, maximum increments of one
29、 percentof the rated 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 or tackle.9. Test Specimens9.1 Th
30、e 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 astructural engineer prior to tes
31、ting. 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 capacity shall beselected random
32、ly 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 accordance with Practice C192at b
33、ase 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 of this standard.10.2 To determin
34、e cracking load apply load and recordactual load values in the following sequence:10.2.1 Apply load in increments of 10 to 20 percent of thecalculated ultimate load up to 90 % of calculated cracking load.10.2.2 Apply additional load in smaller increments on theorder of 1 % to 5 % of calculated ultim
35、ate 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 capacity apply load and re
36、cord actual load valuesin the following sequence:10.3.1 Apply load in increments of 10 to 20 percent 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. Hold the loadafter each
37、 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 calculated ultimate loadand
38、 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, secondcrack (zero tension mome
39、nt), 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 crack (zero tension), a
40、nd 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, including diameter at gr
41、ound 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 (zero tension) moment
42、.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 Photographs of cracks on ten
43、sion side showinglocation of first crack.12.2.2 Photographs of failure area showing location andsize of failure region.C1824 16312.2.3 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.13. Precision and Bia
44、s13.1 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; steel lighting pole; ul
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