Technical Manual

Inc.

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APPENDIX 3D

MODEL SPECIFICATION – HYDRAULICALLY-DRIVEN PUSH PIER SYSTEMS

Chapter 3

Hydraulically-Driven Push Piers

3.1.19 Nominal Strength: A term used in structural design which is defined as the structure or

member capacity at a specified strength limit state. See Ultimate Pier Capacity.

3.1.20 Pier Tube: Hollow steel shaft sections that follow the starter tube section. The pier tubes

have slip-fit internal couplings and are hydraulically advanced to the required bearing depth.

3.1.21 Push Pier System: A hydraulically-driven retrofit deep foundation that utilizes high-

strength round steel tube and a load-transfer bracket (retrofit bracket) to stabilize and/or

lift sinking or settling foundations. The system uses the weight of the structure and any

contributory soil load above the footings to create the reaction to hydraulically advance

(push) the pier tubes.

3.1.22 Resistance Factor: A factor that accounts for the probability of deviation of the actual

resistance (strength) from the predicted nominal resistance (strength) due to variability

of material properties, workmanship, type of failure and uncertainties in the analysis

(Load and Resistance Factor Design).

3.1.23 Safety Factor: The ratio of the ultimate pier capacity to the nominal or service load used

for the design of any push pier component or interface (Allowable Stress Design).

3.1.24 Service Load: See “Nominal Load” above.

3.1.25 Starter Tube: The lead pier tube that is hydraulically driven to the bearing stratum to

create end bearing resistance of the push pier system. The starter tube has a friction

reduction collar at the pier tip to create a temporary annular space between the shaft

and the surrounding soil during installation.

3.1.26 Ultimate Pier Capacity: The push pier capacity based on the least capacity determined

from applicable ultimate limit states for mechanical and geotechnical capacity.

APPROVED PUSH PIER MANUFACTURERS

4.1 Foundation Supportworks®, Inc., 12330 Cary Circle, Omaha, NE 68128; Phone: (800) 281-

8545; Fax: (402) 393-4002.

4.2 Due to the special requirements for design and manufacturing of push pier systems, the systems

shall be obtained from Foundation Supportworks®, Inc., or other qualified manufacturer with an

approved equivalent product. A request to substitute any other manufactured push pier product

must be submitted to the Owner for review not less than seven (7) calendar days prior to the bid

date. The request must include:

4.2.1 Documentation of at least five years of production experience manufacturing push piers

systems,

4.2.2 Documentation that the manufacturer’s push pier systems have been used successfully

in at least five engineered construction projects within the last three years,

4.2.3 Product acceptance by the local building code official(s) having jurisdiction over the

project, and/or

4.2.4 Current ICC-ES or IAPMO product evaluation report or complete description of product

testing and manufacturing quality assurance programs used to assess and maintain

product quality and determine product mechanical strength and geotechnical capacity.