ANSI EP486.2-2012 Shallow Post and Pier Foundation Design.pdf

1、 ANSI/ASAE EP486.2 OCT2012 (R2016) Shallow Post and Pier Foundation Design American Society of Agricultural and Biological Engineers ASABE is a professional and technical organization, of members worldwide, who are dedicated to advancement of engineering applicable to agricultural, food, and biologi

2、cal systems. ASABE Standards are consensus documents developed and adopted by the American Society of Agricultural and Biological Engineers to meet standardization needs within the scope of the Society; principally agricultural field equipment, farmstead equipment, structures, soil and water resourc

3、e management, turf and landscape equipment, forest engineering, food and process engineering, electric power applications, plant and animal environment, and waste management. NOTE: ASABE Standards, Engineering Practices, and Data are informational and advisory only. Their use by anyone engaged in in

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5、otecting themselves against liability for infringement of patents. ASABE Standards, Engineering Practices, and Data initially approved prior to the society name change in July of 2005 are designated as “ASAE”, regardless of the revision approval date. Newly developed Standards, Engineering Practices

6、 and Data approved after July of 2005 are designated as “ASABE”. Standards designated as “ANSI” are American National Standards as are all ISO adoptions published by ASABE. Adoption as an American National Standard requires verification by ANSI that the requirements for due process, consensus, and o

7、ther criteria for approval have been met by ASABE. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessa

8、rily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be made toward their resolution. CAUTION NOTICE: ASABE and ANSI standards may be revised or withdrawn at any time. Additionally, procedures of ASABE require that action be taken periodically t

9、o reaffirm, revise, or withdraw each standard. Copyright American Society of Agricultural and Biological Engineers. All rights reserved. ASABE, 2950 Niles Road, St. Joseph, Ml 49085-9659, USA, phone 269-429-0300, fax 269-429-3852, hqasabe.org ASAE EP486.2 OCT2012 (R2016) Copyright American Society o

10、f Agricultural and Biological Engineers 1 ANSI/ASAE EP486.2 OCT2012 (R2016) Revision approved October 2012 as an American National Standard Shallow Post and Pier Foundation Design Developed by the ASAE Post and Pole Foundation Subcommittee; approved by the Structures and Environment Division Standar

11、ds Committee; adopted by ASAE March 1991; revised editorially December 1992; reaffirmed December 1995, December 1996, December 1997, December 1998; revised December 1999; approved as an American National Standard October 2000; reaffirmed by ASAE February 2005;reaffirmed by ANSI March 2005; periodic

12、review extension for two years approved October 2009; revised October 2012; revision approved by ANSI October 2012; editorial revision June 2013; reaffirmed by ASABE and ANSI December 2016. Keywords: Foundation, Post, Shallow, Structures 1 Purpose and scope 1.1 Purpose. The purpose of this Engineeri

13、ng Practice is to present a procedure for determining the adequacy of shallow, isolated post and pier foundations in resisting applied structural loads. This Engineering Practice will help ensure that soil and backfill are not overloaded, foundation elements have adequate strength, frost heave is mi

14、nimized, and lateral movements are not excessive. 1.2 Scope. This engineering practice contains safety factors and other provisions for allowable stress design (ASD) which is also known as working stress design, and for load and resistance factor design (LRFD) which is also known as strength design.

15、 It also contains properties and procedures for modeling soil deformation for use in structural building frame analyses. 1.2.1 Limitations. Application of this Engineering Practice is limited to post and pier foundations with the following characteristics: Vertically installed in relatively level te

16、rrain; Concentrically-loaded footings; Minimum post or pier foundation spacing equal to the greater of 4.5 times the maximum dimension of the post/pier cross-section, or three times the maximum dimension of a footing or attached collar. 2 Normative references The following referenced documents are i

17、ndispensable for the application of this document. For dated references, only the edition cited applies unless noted. For undated references, the latest approved edition of the referenced document (including any amendments) applies. 2.1 Structural design specifications ACI 318, Building Code Require

18、ments for Structural Concrete and Commentary ANSI/AWC NDS, National Design Specification (NDS) for Wood Construction with Commentary ANSI/ASAE EP484, Diaphragm Design of Metal-Clad, Wood-Frame Rectangular Buildings ASAE EP486.2 OCT2012 (R2016) Copyright American Society of Agricultural and Biologica

19、l Engineers 2 ANSI/ASAE EP559, Design Requirements and Bending Properties for Mechanically Laminated-Wood Assemblies ASCE/SEI 7-10, Minimum Design Loads for Buildings and Other Structures SEI/ASCE 32 Design and Construction of Frost-Protected Shallow Foundations 2.2 Laboratory soil testing standards

20、 ASTM D422, Standard Test Method for Particle-Size Analysis of Soils ASTM D854, Standard Test Methods for Specific Gravity of Soil Solids by Water Pycnometer ASTM D2166, Standard Test Method for Unconfined Compressive Strength of Cohesive Soil ASTM D2435, Standard Test Methods for One-Dimensional Co

21、nsolidation Properties of Soils Using Incremental Loading ASTM D2487, Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) ASTM D2850, Standard Test Method for Unconsolidated-Undrained Triaxial Compression Test on Cohesive Soils ASTM D3080, Stan

22、dard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions ASTM D4318, Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils ASTM D4643, Test Method for Determination of Water (Moisture) Content of Soil by Microwave Oven Heating ASTM D4767, S

23、tandard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils 2.3. In-situ soil testing standards ASTM D1586, Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils ASTM D2573, Standard Test Method for Field Vane Shear Test in Cohesi

24、ve Soil ASTM D3441, Standard Test Method for Mechanical Cone Penetration Tests of Soil ASTM D4719, Standard Test Method for Prebored Pressuremeter Testing in Soils ASTM D1194, Standard Test Method for Bearing Capacity of Soil for Static Load and Spread Footings (withdrawn 2003) ASTM D4750, Standard

25、Test Method for Determining Subsurface Liquid Levels in a Borehole or Monitoring Well (Observation Well) ASTM D5778, Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils 2.4 Preservative-treated wood standard AWPA U1, Use Category System: User Specification fo

26、r Treated Wood 2.5 Nomenclature standard ANSI/ASABE S618, Post-Frame Building System Nomenclature ASAE EP486.2 OCT2012 (R2016) Copyright American Society of Agricultural and Biological Engineers 3 3 Definitions 3.1 Foundation types and components 3.1.1 backfill: Material filling the excavation aroun

27、d a post or pier foundation. See Figure 5. 3.1.2 collar: Foundation component attached to a post or pier, and that moves with it to resist lateral and vertical loads. See Figure 5. 3.1.3 driven pier or post: A pier or post that is pounded or turned into the ground. A pier or post foundation not requ

28、iring prior soil excavation. Also referred to as a displacement pier or post. See Figure 2. 3.1.4 footing: Foundation component at the base of a post or pier that provides resistance to vertical downward forces. When properly attached to the post/pier, a footing aids in the resistance of lateral and

29、 vertical uplift forces, and embedment depth is measured to the base of the footing instead of to the top of the footing. See Figures 1 through 5. 3.1.5 helical pier: A pier comprised of a steel pipe or tubing with an attached helix or helices. See Figure 2. Helices are also known as auger flighting

30、. A helical pier is a type of driven pier that is turned into the soil in a manner that minimizes soil movement/displacement. 3.1.6 pedestal: A relatively short column that can support vertical forces, but is not designed to transmit horizontal shear, and bending moments. This engineering practice i

31、s not applicable to the design of pedestals. 3.1.7 pier: A relatively short column partly embedded in the soil to provide lateral and vertical support for a building or other structure. Piers include members of any material with assigned structural properties such as solid or laminated wood, steel,

32、or concrete. Piers differ from embedded posts in that they seldom extend above the lowest horizontal framing element in a structure, and when they do, it is often only a few centimeters. See Figures 2 through 4. 3.1.8 pier foundation: An assembly consisting of a pier and all below-grade elements, wh

33、ich may include a footing, uplift resistance system, and collar. See Figure 3. 3.1.9 pile: A relatively long and slender column driven, screwed, jacked, vibrated, drilled or otherwise installed into soil to provide lateral and vertical support for a structure. Generally used to carry loads through w

34、eak layers of soil to those capable of supporting such loads. This engineering practice is not applicable to the design of piles. 3.1.10 pole: A round post. 3.1.11 post: A structural column that functions as a major foundation element by providing lateral and vertical support for a structure when it

35、 is embedded in the soil. Posts include members of any material with assigned structural properties such as solid or laminated wood, steel, or concrete. See Figures 1 and 5. 3.1.12 post foundation: An assembly consisting of an embedded post and all below-grade elements, which may include a footing,

36、uplift resistance system, and collar. See Figure 1. 3.1.13 screw anchor: A helical pier primarily designed to handle uplift or tension forces. 3.1.14 shallow foundation: A foundation for which deformation under load is small, so foundation movement approximates rigid body motion. Foundation deformat

37、ion is kept small by selection of foundation depth, d, and post/pier bending stiffness, Ep Ip. 3.1.15 uplift resistance system: Elements attached to an embedded post or pier, generally near the base, to increase the uplift resistance of a foundation system. See Figures 1 through 5. ASAE EP486.2 OCT2

38、012 (R2016) Copyright American Society of Agricultural and Biological Engineers 4 3.2 Foundation geometry and constraints 3.2.1 constrained post (or pier): A post or pier foundation that is restrained from significant horizontal movement at the ground surface, typically by a concrete slab. 3.2.2 fou

39、ndation depth, dF: Vertical distance from the ground surface to the bottom of a post or pier foundation. Typically the vertical distance from the ground surface to the base of the footing. 3.2.3 non-constrained post (or pier): A post or pier foundation that is not restrained from moving horizontally

40、 at or above the ground surface. 3.2.4 post (or pier) embedment depth, d: Vertical distance from the ground surface to the bottom of the embedded post or pier. Includes the thickness of the footing when the footing is rigidly attached to the post/pier or is cast integrally with the post/pier. 3.2.5

41、post (or pier) width, B: The cross-sectional dimension that is perpendicular to the direction of lateral post/pier movement. This width defines the area of contact between the foundation and soil that resists lateral post/pier movement. The width of a round post or pier is its diameter. 3.3 Material

42、 properties and characteristics 3.3.1 cohesion of soil, c: Component of soil shear strength due to cementation or bonding at particle contacts resulting from ionic bonds, hydrogen bonds, and gravitational attraction. 3.3.2 controlled low-strength material (CLSM): A self-leveling and self-compacting,

43、 cementitious material with an unconfined compressive strength of 8 MPa (1200 psi) or less. Other terms used to describe controlled low-strength material (CLSM) include flowable fill, unshrinkable fill, controlled density fill, flowable mortar, flowable fly ash, fly ash slurry, plastic soil-cement a

44、nd soil-cement slurry. 3.3.3 constant of horizontal subgrade reaction, nh: Soil property used in the calculation of horizontal soil stiffness. When divided by post/pier width b, the constant of horizontal subgrade reaction establishes the rate at which the modulus of horizontal subgrade reaction inc

45、reases with depth. 3.3.4 dry bulk density of soil, D: Oven-dried mass of a soil divided by its in-situ volume. Also known as dry unit weight. 3.3.5 effective stress: Net stress across points of contact of soil particles, generally considered as equivalent to the total stress minus the pore water pre

46、ssure. 3.3.6 frost heave: Surface distortion caused by volume expansion within the soil when water freezes and ice lenses form. 3.3.7 moist bulk density of soil, : Mass of a soil divided by its in-situ volume. Also known as wet unit weight. 3.3.8 Poissons ratio, : Transverse (lateral) strain divided

47、 by the corresponding axial (longitudinal) strain that occurs when a uniformly distributed axial load is applied to a soil sample whose transverse expansion is not restricted during load application. 3.3.9 soil friction angle, : Slope angle of Mohr-Coulomb shear strength criterion for soils, where s

48、hear strength = tan + c. 3.3.10 swelling soil: A soil material, particularly clays, that exhibit expansion with increasing moisture content, and shrinkage with decreasing moisture content. Also referred to as an expansive soil. 3.3.11 total stress: Total pressure exerted in any direction by both soi

49、l and water. 3.3.12 undrained shear strength, SU: Shear strength of soil sheared such that pore water pressure is not ASAE EP486.2 OCT2012 (R2016) Copyright American Society of Agricultural and Biological Engineers 5 allowed to dissipate (i.e., undrained condition). Shear strength criterion typically used for short-term loading of soil with significant clay content. 3.3.13 Youngs modulus for soil, ES: Uniaxial compressive stress divided by the corresponding uniaxial strain of a soil sample whose transverse (lateral) expansion i