Details:

Creators:
Abu-Farsakh, Murad Y. ; Yoon, Sungmin ; Tsai, Ching
Abu-Farsakh, Murad Y. ; Yoon, Sungmin ; Tsai, Ching Less -
Corporate Creators:
Louisiana Transportation Research Center
Subject/TRT Terms:
[+]
CPT Driven Pile Capacity Load Factor Load Factor Design LRFD Piles (Supports) Piling (Civil Engineering) Precast Concrete Prestressed Concrete Reliability Analysis Static Analysis Static Load Test
Publication/ Report Number:
FHWA/LA.09/449
Resource Type:
Brief
Geographical Coverage:
Louisiana
Edition:
LTRC technical summary report 449
Corporate Publisher:
Louisiana Transportation Research Center
NTL Classification:
NTL-HIGHWAY/ROAD TRANSPORTATION-Construction and Maintenance;NTL-HIGHWAY/ROAD TRANSPORTATION-Design;NTL-HIGHWAY/ROAD TRANSPORTATION-Materials;
Abstract:
The allowable stress design (ASD) method had been used for many years in the design of bridges, which involves applying a factor of safety (FS) to account for uncertainties in applied loads and soil resistance. The magnitude of FS depends on the importance of the structure, the confidence level of material properties, and design methodology. However, the selection of FS is empirical and does not distinguish between variations in various components of loads and resistances, even though there are significant differences in the risk among each load and resistance components. Bridge design specifications published by the American Association of State Highway and Transportation Officials (AASHTO) has introduced the load and resistance factor design method to separately address uncertainties associated with estimated loads and resistances in bridge design. Since then bridge superstructures have been designed using the load and resistance factor design (LRFD) method, while the ASD method is still used for the bridge foundation design due to difficulties in implementing the LRFD method to foundation designs. This practice can lead to inconsistent levels of reliability between super- and sub-structures. In an effort to maintain a constant level of reliability, the Federal Highway Administration and AASHTO set a transition date of October 1, 2007 after which all federally funded new bridges including substructures shall be designed using the LRFD method. The current AASHTO design specification recommends resistance factors for single driven piles in axial compression ranging from 0.10 to 0.65, depending on the design method. However, the existing resistance factors are recommended based on a pile load test a soil database that was collected from sites that do not necessarily reflect Louisiana soils or design practice. Therefore, resistance factors recommended by the AASHTO code need to be verified before being applied to local soil condition and design practice. Direct application of the AASHTO resistance factors without calibration may result in over-conservative or unsafe design. When local experience and databases are available, AASHTO recommends calibrating the resistance factor using reliability analyses to produce an overall reliability level that is consistent with local practice.
Format:
PDF
Funding:
LTRC project 07-2GT ; State project 736-99-1408
LTRC project 07-2GT ; State project 736-99-1408 Less -
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:228a23d57cd47bc5c92389d4749448ca3cb345b5b352736667fd616187ab5316
Download URL:
https://rosap.ntl.bts.gov/view/dot/22300/dot_22300_DS1.pdf
File Type:

Supporting Files

• No Additional Files

More +