Location

Chicago, Illinois

Session Start Date

4-29-2013

Session End Date

5-4-2013

Abstract

In the recent decades construction of tower structures in big cities around the world is a new trend that has been followed. As a result, engineers are faced with foundations to be designed and constructed under heavier super structural loads imposed by such structures. Often, poor subsoil conditions, site heterogeneity, variability in geometry, and high seismicity brings further challenge in cost effective and safe foundation design. To overcome such complexities and meet higher load capacity requirements often barrette foundations have been utilized instead of cast in situ circular large diameter piles. In this paper applications of barrette foundations together with the emphasis on key issues controlling their design and construction are presented using two recent case histories from Turkey. The first case history, is a covered sports arena with a capacity of 18,000 thousand people and is constructed at the Asian part of Istanbul. Main lithological units underlying the site are the upper uncontrolled fill of variable thickness and underlying bedrock. The second case history is Folkart Towers, Europe’s 5th highest twin towers project in Izmir presently under construction. Subsoil conditions at the site is very poor with alternating layers of alluvium consisting of gravel, sand, silt and clay layers with very high groundwater table. Both sites have very high past seismic activity. In the first case, foundations are designed and constructed by means of socketed barrettes into the underlying bedrock. The design loads of barrettes considering only skin resistance along the socket are estimated using empirical equations proposed by various authors in the past. In the second case, both skin resistances and tip resistance developed are estimated using mechanical modeling of subsoils determined as a result of soil characterization by means of in situ measurements using similar procedures utilized in circular pile design. In both cases, estimated capacities are checked at the design stage by means of O’Cell load testing performed on constructed barrettes at a representative location of the site in order to end up with safe and economical foundation design. Verticality and constructability of barrettes having long lengths are another key issues to be considered during design and construction. Instrumentation and monitoring techniques that could be utilized to ensure verticality are also presented within Folkart twin towers project.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Seventh Conference

Publisher

Missouri University of Science and Technology

Publication Date

4-29-2013

Document Version

Final Version

Rights

© 2013 Missouri University of Science and Technology, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 29th, 12:00 AM May 4th, 12:00 AM

Barrette Foundations — Two Case Histories from Turkey

Chicago, Illinois

In the recent decades construction of tower structures in big cities around the world is a new trend that has been followed. As a result, engineers are faced with foundations to be designed and constructed under heavier super structural loads imposed by such structures. Often, poor subsoil conditions, site heterogeneity, variability in geometry, and high seismicity brings further challenge in cost effective and safe foundation design. To overcome such complexities and meet higher load capacity requirements often barrette foundations have been utilized instead of cast in situ circular large diameter piles. In this paper applications of barrette foundations together with the emphasis on key issues controlling their design and construction are presented using two recent case histories from Turkey. The first case history, is a covered sports arena with a capacity of 18,000 thousand people and is constructed at the Asian part of Istanbul. Main lithological units underlying the site are the upper uncontrolled fill of variable thickness and underlying bedrock. The second case history is Folkart Towers, Europe’s 5th highest twin towers project in Izmir presently under construction. Subsoil conditions at the site is very poor with alternating layers of alluvium consisting of gravel, sand, silt and clay layers with very high groundwater table. Both sites have very high past seismic activity. In the first case, foundations are designed and constructed by means of socketed barrettes into the underlying bedrock. The design loads of barrettes considering only skin resistance along the socket are estimated using empirical equations proposed by various authors in the past. In the second case, both skin resistances and tip resistance developed are estimated using mechanical modeling of subsoils determined as a result of soil characterization by means of in situ measurements using similar procedures utilized in circular pile design. In both cases, estimated capacities are checked at the design stage by means of O’Cell load testing performed on constructed barrettes at a representative location of the site in order to end up with safe and economical foundation design. Verticality and constructability of barrettes having long lengths are another key issues to be considered during design and construction. Instrumentation and monitoring techniques that could be utilized to ensure verticality are also presented within Folkart twin towers project.