Details:

Creators:
Roeder, Charles ; Lehman, Dawn
Roeder, Charles ; Lehman, Dawn Less -
Corporate Creators:
Washington State Transportation Center
Corporate Contributors:
Washington (State). Dept. of Transportation. Research Office ; United States. Federal Highway Administration
Washington (State). Dept. of Transportation. Research Office ; United States. Federal Highway Administration Less -
Subject/TRT Terms:
[+]
Bridge Foundations Bridges Bridge Substructures Caissons Concrete Concrete Filled Tubes Connections Piles (Supports) Structural Connection Tubing
Publication/ Report Number:
WA-RD 776.1
Resource Type:
Tech Report
Geographical Coverage:
Washington
Edition:
Research report.
Corporate Publisher:
Washington (State). Dept. of Transportation. Office of Research and Library Services
Abstract:
The Washington State Department of Transportation (WSDOT) frequently employs deep pile or caisson bridge

foundations for its bridge structures. Deep pile and drilled shaft foundations are increasingly important for seismic

design in Washington state, because of increased seismic design load demands in bridge design specifications. A

common caisson is a reinforced concrete filled tube caisson. Although these types of foundation elements are

common, there are few guidelines on their design. As a result, current WSDOT design methods are conservative

and neglect the many benefits provided by composite action of the concrete and the steel tube, which may result in

increased cost and size of the foundation. Recent research on composite concrete filled steel tubes (CFT) shows

significant benefit for applications using CFT elements, in particular that CFT elements can develop more lateral

resistance and greater inelastic deformation capacity with less deterioration of resistance than reinforced concrete

elements of the same weight and diameter. Hence the use of this composite action permits smaller diameter and

shorter caisson foundations resulting in cost savings associated with a smaller piles and drilled shafts, less material

and reduced construction time and cost. This research involves consideration of the composite properties of CFT

members with internal reinforcement, and this special case of internally reinforced CFT is identified as RCFT in

this report.

The research study used analytical tools verified using past experimental and analytical research on CFT

members and foundation connections without internal reinforcement. The research included comprehensive review

of past research results including experiments and analysis of CFT and RCFT elements and connections. Design

models were evaluated and compared to prior test results to determine their accuracy and reliability. A

comprehensive analytical study was performed to extend this prior research to current WSDOT RCFT applications.

The analytical studies were calibrated to past experimental results to document their accuracy, and the analysis

included development of basic design models, fiber or section based analysis, and detailed continuum based models.

No experiments were included in this initial study, but observations from prior experimental research were to be

used to support the work. The goals of this preliminary study were to develop initial answers to uncertainly in the

design process of these components and their connections to permit the WSDOT to begin to employ the benefits of

composite action for these sub-structural systems. To that end, specific design recommendations from this

preliminary research study are provided. Finally, an overview of the additional research needed to further develop

the deep foundation system is provided.


Format:
PDF
Funding:
Agreement T4118, Task 58
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:3106e7c9bc32e80ed1f951915751f3b1601f86b72a6fc0ab10f4b1213cc552c6
Download URL:
https://rosap.ntl.bts.gov/view/dot/24435/dot_24435_DS1.pdf
File Type:

Supporting Files

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