Details:

Creators:
McVay, Michael ; Klammler, Harald
McVay, Michael ; Klammler, Harald Less -
Corporate Creators:
University of Florida. Dept. of Civil and Coastal Engineering
Subject/TRT Terms:
[+]
CAPWAP Concrete Design Load Distributions (Statistics) EDC Girder Bridges Ground Settlement Load Factor Load Limits Load Tests LRFD F PDA Pile Groups Pile Monitoring Prestressed Concrete Bridges Random Variables Reliability Reliability (Statistics) Tolerance (Physiology)
Resource Type:
Tech Report
Geographical Coverage:
Florida
Edition:
Final report; 09/24/09-06/30/11.
Corporate Publisher:
Florida Department of Transportation
Abstract:
Current department of transportation (DOT) and Federal Highway Administration (FHWA) practice has highly

variable load and resistance factor design (LRFD) resistance factors, Φ, for driven piles from design (e.g., Standard

Penetration Tests (SPT), Cone Penetrometer Test (CPT)) to construction (e.g., pile monitoring). Complicating the

construction effort, are the number of piles monitored (e.g., 10% versus 100%), as well as the type of monitoring (e.g., high

strain rate: Embedded Data Collector (EDC), Pile Driving Analyzer (PDA), static load test, etc.). Of great interest are

quantifying the influence of number of piles within a group, number of piles monitored, as well as spatial variability on a

pile group’s uncertainty and associated LRFD Φ factors.

The work started with an investigation of probability of failure (POF) of a bridge in terms of its piers and underlying

piles. It was discovered that the number of piles in a pier may have a large impact on POF of a pier, which is why the

development of LRFD Φ should occur with respect to pier (i.e., pile group) level and include the total number of piles

within the group as well as the distribution of monitored and unmonitored piles within the group. Next, the total

uncertainty of the pier including spatial variability and error of the method (e.g., SPT, EDC/PDA, etc.) was investigated. The work started with spatial uncertainty of single pile resistance (side plus tip) from SPT data and then extended through

kriging (considering different weights for individual borings) to group layouts (e.g., double, triple, quads, etc.) for assessing

group resistance uncertainty, CVR. Subsequently, the kriging group work was carried over to assessing uncertainty, i.e.,

spatial and method error (predicted versus static load test) for high strain rate field measurements. Equations and charts

were developed to quantify group uncertainty, CVR, and LRFD Φ for typical group layouts and monitoring. The latter

approach was considered to be inflexible, and the spatial uncertainty (i.e., kriging) was replaced with hammer monitoring

in conjunction with high strain rate monitoring. Using the uncertainty of monitoring method (CV εm) and a measured

uncertainty of blow count regression (CVεh) versus high strain rate monitoring, an LRFD Φ equation was developed for pile

groups considering the numbers of monitored and unmonitored piles. The developed expression was evaluated at two sites

and gave reasonable predictions compared to current practice.


Format:
PDF
Funding:
BDK-75-977-25
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:6a54db2f2771f637c9c8190e63403c83015946aacd53caf95bed2055ce9a72c4
Download URL:
https://rosap.ntl.bts.gov/view/dot/20543/dot_20543_DS1.pdf
File Type:

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