b'Torque Anchor Holding CapacityThecapacityofahelicalproductcanbe acceptance,theusefulcapacityofthepileorestimatedbyaccuratelymeasuringthe anchor has been exceeded.The load incrementinstallationshafttorsion.Severalmethodsare priortothisfinalloadincrementshallbecommonlyused.Transducersattachedtothe recorded as the ultimate capacity of the product.hydraulic lines, strain gauge monitors, shear pins Loadcapacityisdiscussedingreaterdetailinandmonitoringpressuredifferentialacrossthe Chapter 2 of this technical manual.installationmotorareallcommonwaysto Soiltypewillaffecttheperformanceofthedetermine installation torque being applied to the helicalproductduringfieldtesting.Foranchorshaft. Theaveragerecordedshaft example, piles or anchors installed in clay willtorsionmustbeatorabovethetorque showminimalcreepwithincreasingloadandrequirementduringthefinal threefeetof thensuddenlyandcontinuouslystartmoving.installation to confirm meeting the installation Cohesionlesssoils,ontheotherhand,usuallytorquerequirement.Bycontinuingtoinstall willproduceamorepredictableloadtocreepthehelicalproductbeyondfirstreachingthe curve.shaft torsion requirement insures that all anchorplates are sufficiently embedded into the targetInstallation Torquesoilandthisreducesthechanceofcreep, Shafttorsionduringinstallationcanprovideasettlement or pullout in the future. reasonably accurateestimateoftheexpectedField load testing is required to verify the actual ultimatecapacityofthehelicalproduct.Theloadcapacity.Duringafieldtest,thehelical relationshipbetweentheshafttorsionduringproduct is loaded in the direction of the intended installation and the ultimate capacity of the piercompressive or tensile load and at the intended or anchor is empirical and was developed frominstallationangle.ASTMD1143andASTM resultsfromthousandsoftests.Whenone3689fieldloadtestsmeasuretheultimate appliesrotationaltorsiontoashaftatgrade,capacityofthehelicalproductwhenfully someofthetorqueenergyislostbeforeitloaded.Thereisnormallyasmallshaft reaches the helical plates at the bottom end of themovementwhenahelicalproductisinitially shaft.This is due to friction between the shaftloaded due to seating the plates into the soil. and the soil.This movement is normally not considered in the Figure2,below,illustratesthatnotallofthetestmeasurement.Beforebeginningthefield torque applied to the shaft by the motor reachesload test, a small initial seating load of 1,500 the helical plates.The actual torque applied toto 2,000 pounds is usually applied to the pile or the helical plates is T Plates= T Motor - T Shaft .Theanchorpriortocommencingtestprocedures. friction generated between the circumference ofDuringtesting,theloadonthehelicalshaftis theshaftandthesoilisdirectlyrelatedtotheincrementally increased and after applying each shaftconfigurationandsizealongwiththeload increment the movement at the top of the propertiesofthesoil.Becauseofthislossofshaft is measured against a fixed point.If creep efficiency in transmitting the motor torque downoccursonlyduringtheapplicationofthe to the plates, an empirical Soil Efficiency Factorincrementalload,thetestcancontinue (k) must be employed to arrive at a reasonableimmediatelyaftermeasuringtheinitialcreep estimate of pile or anchor ultimate capacity.increment.Astheloadincreasesandnearsultimatecapacity,thepileoranchormay Shaft torsion should always be monitored duringcontinuetoslowlymoveforaperiodoftime theinstallationofhelicalscrewpilesandafter the incremental load was applied.During anchors.Generally,theultimateholdingthistimetheincrementalloadonthehelical Torque fromShaft Frictionproductmustbemaintainedastheshaft = T shaft Motor Appliedcontinues to creep.The total deflection shall not to Shaft = T Motorbe determined until the movement ceases and thepile or anchor becomes stable.If after 15 to 20minutes, the movement is continuing or the totalmeasured creep exceeds the established limit for Helical Plate Figure 2 .Friction = T platesECP Helical Torque Anchors Technical Service Manual Figure 2 .2021 Earth Contact Products, L.L.C.2021-09 Chapter 1 - Page 26 All rights reserve'