b'Pier pipe stiffness (Moment of Inertia) increases with PIER SECTIONincreasing diameter and/or wall thickness.Graph 5 shows reductions in allowable axial compressive loading INERTIA SLEEVErelative to the exposed length of the pier pipe in air or water forvarious pier diameters and with sleeved pier configurations. WhenECP Steel Pierpipe is fully exposed or passes through very weaksoils, we recommend installing sleeving over and/or inside the pierpipe to increase the bending strength of the pier; in addition, it isgood practice for the designer to consider using a larger diameterpier pipe in weak soil applications.Installing a pier sleeve or selecting a larger diameter pierPIERpipe is used to prevent buckling of the pier pipe. SECTION Pipe Sleeves may be needed in poor soil conditions generally COUPLINGrecognized as soil having Standard Penetration Test (SPT) blowcounts less than, or equal to, five blows per foot (N 5), Pipe Sleeves may be needed where the strength of the coupledjoints or stiffness (axial moment of inertia) of the pier pipe are aconcern. INERTIASLEEVE Pipe Sleeves are usually installed where the pier pipe is exposed, COUPLINGor may become exposed.PIER TYPICALSECTION ASSEMBLYHow to Reinforce Piers to Increase Buckling Resistance: There DETAILare several ways to reinforce pier pipe in such situations.One ofthe simplest to slightly improve pier stiffness and to strengthen thecoupled joints is to grout the pier pipe after installation.Many Figure 4. Details of ECPs PPB-designers also require that the contractor install a reinforcing bar 300-IS patented Inertia Sleevein the center of the pier pipe along with the grouting to improve and howthe piercouplingisjoint strength. strengthened. (ICC ESR 4771)InertiaSleeveEarth ContactProductsoffersapatentedproductcalledthe InertiaSleevetoimprove shaft stiffness.This unique product is shown in Figure 4, and is the most economical way toquickly enhance the axial moment of inertia (stiffness) of the pier system.The Inertia Sleeve is easy toinstall, but must be installed concurrent with driving the pier pipe.One simply drops an Inertia Sleevesectioninto themost recentlyinstalled sectionofpierpipe.Thismustbedonepriortocouplingtogether and driving the next section of pier pipe. Inertia sleeves have an ICC evaluation and ICC-ES4771 has been issued.Thelowcost Inertia Sleevetakes Table 13STEEL PIER SHAFT STIFFNESS COMPARISONnearly no labor to install and instantlyCross Moment of Pier Stiffnessincreases the rigidity and strength of the Steel Pier Pipe Configuration Section Inertia- in 4 Relative topiershaftthroughweaksoil.The Area- in 2 (Stiffness) PPB-350-EPSuniquedesignofthepatented Inertia PPB-300-EPS (2-7/8 dia.) 1.41 1.29 0.55%Sleevealsostrengthensthecoupled PPB-300-EPS + PPB-300-IS 2.65 1.81 0.77%joints.The coupling connection of the Inertia PPB-350-EPS (3-1/2 dia.) 1.68 2.35 100%Sleeve passesthroughthepierpipe PPB-350-EPS + PPB-350-IS 3.46 4.22 180%coupling completelyandengageswith PPB-400-EPS (4 dia.) 2.60 4.66 198%thepreviouslyinstalledsectionof PPB-350-EPS + PPB-350-ES 4.27 7.01 298%InertiaSleeve.Thecouplingsare PPB-350-EPS + PPB-350-ES +thereforedoubledandstaggered, PPB-350-IS 5.12 8.88 379%providing a strengthened coupled joint. EPS = Pier Pipe SectionIS = Internal Inertia Sleeve ES = 4 External SleeveECP Steel Piers - Technical Design Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 6 - Page 128 All rights reserved'