SUBSTRUCTURE SUPPORT, INC. | 106 LINDEN ST. SUITE 201 | OAKLAND, CA 94607 (510) 835‐2273 | www.SUBSTRUCTURESUPPORT.COM
January 2010
TORQUE DOWN PILES™ CLIENT’S REPORT Torque Down Piles
Contents
Torque Down Piles™ (TDPs) are rapidly becoming the deep pile foundation of choice. TDPs offer higher load capacities, lower costs, faster installations and are installed with virtually no vibration or noise. Structural and geotechnical engineers as well as general contractors continue to solve challenging project conditions and save owners money by choosing TDPs. Substructure Support and our clients all share a common goal: To build our projects quickly, economically, safely, and without change orders.
What are Torque Down Piles? 2
Special Interest
Our clients frequently ask three questions: 1. What are Torque Down Piles?
2. How much do they cost?
3. Are Torque Down Piles right for my project?
The following article is presented to address these questions. Technical information on TDPs is presented in our article, “Torque Down Piles™ – Engineer’s report.” Please visit our website for a brochure.
How much do they cost?
3
Are TDPs right for my project? 4
Completed Projects
5
History of Torque Down Piles 2
Deep foundation terminology 3
d
2
What are Torque Down Piles?
TDPs are a full displacement pipe pile proprietary to Substructure
Support, Inc. and their licensees (patent pending). As the name suggests, full displacement piles push soil into the surrounding formation minimizing the need to off haul spoils. TDPs can be installed in a variety of site conditions. They provide an excellent alternative to driven and drilled deep foundation systems. They offer superior performance in terms of noise pollution, vibration of adjacent improvements and site safety.
Installing the TDP is done with little or no vibration, noise and in most cases pre‐drilling. Therefore, the TDP is an excellent choice for urban infill, medical, civil, airport, and educational projects.
Where a new invention promises to be useful, it ought to be tried. – Thomas Jefferson HISTORY of the TDP All great inventions are developed to solve a problem; such is the case with TDPs. In 2001, Steve Neville was a member of the senior management team for a major development in the Playa Vista district of West Los Angeles. During the first phase of the project, the foundation system consisted of driven concrete piles. These were subsequently abandoned due to excessive noise, vibration and ground heave. Steve was charged with finding a suitable deep foundation alternative. The project required an alternative deep foundation system which was comparable to precast driven piles in terms of cost, load capacity, and production rate, but without spoils, and reduced ground heave, vibration and noise. Unable to find an existing deep foundation system that met all of these criteria, Steve began the task of developing a new system himself: the Torque Down Pile. The TDP was developed over a period of two years before being successfully accepted by the City of Los Angeles. The result of this research and development was the TDP – a 12 ¾ inch diameter full displacement pipe pile with a conical tip superior to driven piles in terms of production, noise and vibration and equal or better in terms of capacity.
Learn more about TDP attributes Each TDP is constructed of high strength 3/8‐inch thick steel pipes with 12 ¾ inch outside diameter. A proprietary conical tip, welded to the end of the pipe, is used to advance the pile into the ground. The tip was developed to minimize spoils and ground heave while maximizing capacity. The piles are screwed into the ground using a high torque drill rig capable of installing up to 40 piles per day. Typical production rates range from 15 to 25 per day. Installing the pile is done with little or no vibration, noise and in most cases no pre‐drilling. Therefore, the TDP is an excellent choice for urban infill, medical, civil, airport, and educational projects. TDPs are generally designed for ultimate capacities in compression ranging between about 400 and 700 kips achieved through a combination of skin friction and end bearing. Higher capacities are possible, and TDP have been tested in excess of 1,000 kips. TDPs can be installed to depths up to 120 feet. As required, rebar is embedded into the pile head to provide connectivity to the overlying structure and the pipe annulus is filled with structural concrete. The design of the TDP facilitates concrete placement and up to 100 piles can be poured per day.
3
How much do TDPs cost?
Torque Down Piles are in many cases the most cost efficient alternative deep foundation system available on the market. Owners, engineers and general contractors choose TDPs as their number one choice for installation speed, capacity, and cost. In general, each TDP costs between $50 and $100 per foot installed.
Cost is mainly affected by site and subsurface conditions, number of
Deep Foundation Terminology
required piles and length.
Deep foundations are foundation systems that transfer building loads through weak or compressible soil to an underlying bearing layer. Typical deep foundation systems consist of pre‐stressed concrete, wood, steel pipe or beams embedded into the bearing layer by mechanical means of drilling, vibrating, driving, crowding or boring. Deep foundations may be selected due to poor soil capacity, challenging site conditions, heavy design loads and geologic/seismic hazards. Full displacement in terms of the TDP, is where piles are installed such that the full diameter of the pipe displaces soil laterally into the surrounding
formation
with
minimal
disturbance. The reduced disturbance during
Learn more about TDPs low cost Substructure Support has the capability to value engineer the TDP system for your project. We provide a tailored solution based on the structural requirements and subsurface conditions, often significantly reducing the cost of the foundation system. Our analyses are based on our experience at similar sites and/or an indicator and load test program. The goal of our analysis is to provide the most efficient design in terms of pile quantity, length and schedule. Substructure Support does not have backend charges for pre‐ drilling, cutoffs or off haul. Backend charges are typical with conventional pile driving systems and are generally difficult to quantify until the end of the project.
compaction of the displaced soil increases the friction between the soil and steel pipe, allowing for higher capacities than traditional driven full displacement piles. Skin friction is defined as the frictional resistance between the pile and the displaced soil. Overall load bearing capacities are enhanced from the soil surrounding the pile during
and
after
advancement
from
densification. End Bearing is the ability of the soil to resist movement of the pile tip through the bearing layer of soil. Piles are usually advanced to a depth where the soil is dense, such as sand, gravel or bedrock, where end bearing can be maximized.
d
4
Are TDPs right for my project? Simply stated, Torque Down Piles are full displacement pipe
piles, priced competitively, and used on a variety of different projects. But are they the right fit for your project? In most cases, our clients choose TDP for load bearing capacity, cost, speed of installation, and the fact that TDP are installed with virtually no vibration or noise. Clients must consider site and subsurface conditions, seismic, and project characteristics when determining if TDP are the right fit.
FACT: Of the last 16 test programs in five years in San Francisco, maximum test loads on TDPs averaged 738 kips in compression and 415 kips in tension.
Advantages of using TDP
Surface conditions. The impact of pile installation on adjacent buildings, streets, sidewalks and utilities must be considered when choosing a deep foundation system within an urban area. Increased soil off‐haul due to ground heave and drilling spoils should also be considered. TDPs reduce the impact of foundation construction on adjacent facilities and therefore, are well‐suited for medical, airport, high‐tech, educational, civil and urban infill projects. TDP can be installed within 16 inches of an adjacent structure with minimal impact on its occupants. Sub‐surface conditions. Many projects are planned on or near sites with high water tables, contaminated soil, loose fill, and highly compressible marine deposits. Potential liquefaction, lateral spreading and differential settlements are common issues along the pacific coast. Where subsurface conditions vary, TDPs are ideal since their length can be adjusted during production pile installation. TDPs mitigate the impact of subsurface conditions on the projects performance and cost. Regional seismicity. The USGS has predicted a 63 percent probability of a magnitude 6.7 or greater earthquake occurring in the San Francisco Bay Area by 2031. Large earthquakes can cause erratic settlement behavior of structures with potentially devastating effects on life and safety. A properly designed and constructed deep foundation system is a common way to reduce damage and maintain life safety of a structure during an earthquake. The steel pipe/concrete construction of the TDP is arguably superior to other deep foundation systems. Schedule. Time is money. Your consideration of the TDP system gives you an opportunity to save both. They are unparalleled in terms of number of piles installed per day, ease of cut‐off and installation of pile cap connections. On average, 15 to 20 piles can be installed per day per drill rig, with as many as 30 to 40 in soft soil conditions.
5
Conclusions
Substructure Support, Inc. 106 Linden Street, Suite 201 Oakland, CA 94607 Office: (510) 835‐2273 Fax: (510) 835‐2464 ‐Featuring the Torque Down Pile‐ Find us on the Web: www.substructuresupport.com
TDPs are rapidly increasing in popularity throughout the greater San Francisco Bay Area and Los Angeles basin/region. Substructure Support is helping structural and geotechnical engineers as well as general contractors solve difficult and challenging site conditions. For estimates or information on becoming a Torque Down Pile licensee, please contact us today at (510) 835‐2273 or e‐mail
[email protected].
PROJECT LISTING Piling Completed May‐02 Playa Vista Lot 07 Benchmark Builders Showroom March‐04 Genentech Building 50 July‐04 Extend Stay America Hotel September‐04 555 4th Street December‐04 Harbor View Lofts March‐05 Bluxome Street Housing November‐05 Saint Thomas More School December‐05 Telesis Building II December‐05 Bay Street Residential December‐05 SOMA Grand Hotel February‐06 Museum Plaza February‐06 Hornet Bookstore July‐06 Aura Tower July‐06 Uptown Oakland October‐06 Cooper Union Building January‐07 San Carlos Market Place April‐07 Orleans Hotel June‐07 650 Eddy Street June‐07 311 2nd and Harrison Street July‐07 Saint Anthony Foundation July‐07 Vanderwater and Francisco September‐07 Building F1 Harvest Hall November‐07 Colony at Jack London Square November‐07 1188 Mission Street Apts March‐08 UC Davis March‐08 9th & Jessie July‐08 2nd and Broadway August‐08 SF Int Airport Secure Connector September‐08 Hastings College of Law October‐08 10th & Mission October‐08 San Jose Airport Term A February‐09 CHP Headquarters April‐09 Alvarado Middle School May‐09 Boeing Building 45 ICBM Lab July‐09 3157 Steiner Street August‐09
Location Los Angeles, CA Los Angeles, CA San Francisco, CA Northridge, CA San Francisco, CA Oakland, CA San Francisco, CA San Francisco, CA Chatsworth, CA San Francisco, CA San Francisco, CA San Francisco, CA Sacramento, CA Sacramento, CA Oakland, CA Sacramento, CA San Carlos, CA Sacramento, CA San Francisco, CA Oakland, CA San Francisco, CA San Francisco, CA Oakland, CA Oakland, CA San Francisco, CA Davis, CA San Francisco, CA Oakland, CA San Francisco, CA San Francisco, CA San Francisco, CA San Jose, CA Sacramento, CA Union City, CA Huntington Beach, CA San Francisco, CA
General Contractor Neville Brothers Vista Management Rudolph & Sletten Magnum Enterprises Granite Excavation & Demo Webcor H & N Development Corp. Nibbi Brothers NTR Consultants Obayashi Corp. Webcor West Builders Boebbelen Management BCN Development Obayashi Corp. Habitat Construction WL Butler JR Roberts / Deacon, Inc. Cahill Builders Overaa Construction Nibbi Brothers RPE Construction Howard S. Wright San Jose Construction Cannon Constructors Drill Tech Cahill Builders Swinerton Builders Hensel Phelps Howard S. Wright Cahill Builders Helsel Phelps Fullmer Construction Sausal Construction RBA Builders JT Builders
Disclaimer. The opinions presented in this article are based on Substructure Support’s experience on completed projects. The performance and constructability of any foundation system is subject to site and subsurface conditions as well as specific project requirements. Prior to selecting the TDP, we would be pleased to present the specific benefits of the TDP for your project to your design team and/or general contractor.