Proceedings of the 42nd Annual Conference on Deep Foundations, 2017, New Orleans, LA, USA, (DFI)
LRFD Resistance Factors for Design of Driven Piles Using the Texas Cone Penetration (TCP) Test
Hoyoung Seo, Ph.D., P.E., William D. Lawson, P.E., Ph.D, James G. Surles, Priyantha W. Jayawickrama, Ph.D. and Rozbeh Moghaddam, Ph.D., P.E.
This study provides calibration of resistance factors (?) for design of driven piles to implement Load and Resistance Factor Design (LRFD) for bridge foundations using Texas Cone Penetration (TCP) Test data. The basic research approach was to compile a database of published full-scale load tests including projects from the Texas Department of Transportation's (TxDOT) historical archive and projects from neighboring state DOTs. Load test results from neighboring states were leveraged by performing new geotechnical borings with TCP tests at the project sites. The final dataset consisted of 30 load tests performed on precast square concrete piles, with pile widths ranging from 356 to 508 mm and penetration depths ranging from 5.2 to 25.5 m, driven in soils. Ultimate capacities for each load test were interpreted based on Davisson, 5%, and 10% settlement criteria. These measured ultimate capacities were compared against predicted capacities estimated from TCP blow count values (N/sub TCP/) and design charts following the procedures outlined in TxDOT's Geotechnical Manual. From the comparisons, statistical parameters of the biases (? = measured capacity/predicted capacity) such as mean and coefficient of variation were obtained. Resistance factors (?) for LRFD were then determined using Monte-Carlo simulations for each ultimate capacity criteria with the target reliability indices of 2.33 and 3.00.
|article #2770; publication #1037 (AM-2017)|