b'Proof Testing and Project Documentation: applicationofthe maximum allowable testThebigadvantage whenusinghydraulically load shown in Table 1, whichever is less.installedECPSteelPiersisthateachpier is 3. The length of time the pier was subjected tofield Proof Tested to a load that is greater than the Proof Test load.force that is required to restore and support the 4. The depth to load bearing.structure.This Proof Testing of each and every 5. After all pier placements have been installedpier placement verifies that firm bearing stratum and ProofTested,theforce required toor rock upon which the pier pipe is founded is recover lost elevation to restore the structuresufficienttosupporttheworkingload at each placement shall be recorded.requirement plus a factor of safety. 6. The amount of lift at each placement.It is recommended that the installer document the Attheendoftheproject,thisdatashallbefollowing data at each pier placement: compiled into a project report and retained by the1. The installation force used to drive each 3-1/2 installerforfuturereference.Theinstallerfoot long section of pier pipe into the soil. should provide a copy of the project report to the2. The Proof Test force that was applied against engineerofrecordorownersrepresentativethe bearing stratum.This force shall be either upon request.the force required to slightly lift the structureusing onlythe drivecylinderortheBuckling Loads on the Pier Shaft in Weak SoilWhenever a slender column (Pier Pipe) does not assumed straight. Equation 3belowishaveadequatelateralsupportfromthe Davissons formula.surroundingsoil,theloadcarryingcapacityof Equation 3: Critical Bucklingthe column is reduced as pipe buckling becomes 2a risk. In the case of ECP Steel Piers, the full P cr= U crE pI p/ Rultimate-limitcapacityshowninTable1is Where:availableprovidedthesoilthroughwhichthe P cr= Critical Buckling Loadlbpier penetrates maintains a Standard Penetration U cr= Dimensionless ratio (Assume = 1)Test value N 5 blows per foot through the E p= Shaft Mod. of Elasticity = 30 x 10 6psientire depthofthepierinstallation.Thepier I p= Shaft Moment of Inertia = in 4mustalso be firmly securedtoa foundation R = 4E pI p/ k Hdbracket d = Shaft DiameterinThe most accurate way to determine the buckling Computeranalysisofshaftbucklingistheload of a pier shaft in weak soil is by performing recommendedmethodtoachievethemosta buckling analysis by finite differences.There accurate results.Many times, however, one mustareseveralspecializedcomputerprogramsthat haveinformationrapidlytoprepareacanperformthisanalysisandallowthe preliminary design or budget proposal.introductionofshaftpropertiesandsoil Table12, below,provides budgetaryconditionsthatcanvarywithdepth.Another, conservative critical buckling load estimates formethod of estimating critical buckling which is variousshaftsizes that penetratethroughlessaccurateisby using DavissonMethod, different types of homogeneous soils.EstimatingBucklingLoadsforPiles (1963).Inthismethod,Davissonassumesvarious Graph 5 onthefollowingpage presentsvisualcombinationsofpileheadandtipboundary representationofBucklingStrength of variousconditions and a constant modulus of sub-grade pier configurations when fullyexposed inair,reaction, k H .Load transfer to the soil due to orwater;thatis,nolateralshaftsupportisskin friction is assumed negligible and the pile is present.It is recommended that a Registered Professional Engineer conduct the design of ECP SteelPiers where the pipe column is likely to be in weak soil and shaft buckling may occur.ECP Steel Piers - Technical Design Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 6 - Page 126 All rights reserved'