Bridge Analysis, Design and Repair

Single Abstract

339415 - A Soil-Structure Interaction Procedure for the Design of Bridges on Drilled Shafts

Friday, April 20
1:30 PM - 3:00 PM
Location: 203A

This study presents a practical way to include deep foundation elements, such as drilled shafts and soil effects (through p-y, t-z and q-z curves), in the modeling of bridges. The explicit inclusion of the foundation elements has many advantages. First, it puts the ability to adjust foundation stiffness (due to scour, liquefaction, etc.) in the hands of the structural engineer. Second, it provides a more accurate solution for finding the plastic hinge location (which could potentially occur below grade) through pushover analysis. Additionally, the correct (natural) boundary condition for top of the pile is internally included, to avoid misconception of idealized pinned or fixed conditions in traditional geotechnical analysis. Last, it permits one to more directly determine how soil effects, like liquefaction, produce changes in the superstructure such as increase of moments in beam or necessity for increased seat lengths. The incorporation of the nonlinearity of p-y, t-z and q-z curves is solved by an iterative process using secant stiffness. Superstructure, substructure and foundations are modeled using finite elements. Shafts are supported by a collection of horizontal (p-y) and vertical (t-z) springs along pile length; at the tip of the shaft a vertical spring (q-z) is included. Early examples have shown that this is a simple process requiring only a few iterations to reach an error of less than 1%. These iterations are performed using linear analysis with typical finite element software in conjunction with spreadsheet processing. The procedure has been used in the analysis and design of White River Bridge an 18-span bridge in a seismic region with large scour, and for several bridges of the California High Speed Rail project where liquefaction was included. The study includes a range of foundations to incorporate both single-shaft and multi-shaft foundations, and describes a process that can also be applicable to buildings and other deep foundations.

Carlos G. Matos

Senior Structural Engineer
Jacobs

Dr. Matos is a senior structural engineer at Jacobs Engineering. An expert in the modeling of complex and long span bridges, he has worked on the design of major projects like the Lewis & Clark Cable Stayed Bridge and the California High Speed Rail. Dr. Matos is an active member of the 12-87 Fracture-Critical System Analysis for Steel Bridges Committee of the National Cooperative Highway Research Program (NCHRP). He has expertise in computational mechanics, Multiphysics, and the development of high performance finite element code and has authored several peer-reviewed papers on computational fracture mechanics and the dynamics of vehicle-structure interaction. Dr. Matos holds a bachelor's degree from the Universidad Nacional de Ingenería Lima-Peru, a master's degree from the University of Texas at Austin, and a PhD from the University of Illinois at Urbana-Champaign. He is a Professional Engineer and Structural Engineer registered in the State of California.

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Andrew Kimmle

Structures
Jacobs

Mr. Kimmle’s structural experience includes structural design and analysis in steel and concrete. He has performed both single-span and multi-span bridge design as well as originating design for unique steel framing fixtures. He has additional experience in earthquake simulation, dynamic analysis and seismic design of steel units. Andrew has had mentored field exposure in both highway and railway bridge construction practices and introduction to bridge inspection procedures. He has worked with CSIbridge, SAP2000, LEAP Bridge Suite, Microstation, AutoCAD and Matlab and has familiarity with AASHTO, AISC, ACI, AREMA, and ASCE structural codes.

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339415 - A Soil-Structure Interaction Procedure for the Design of Bridges on Drilled Shafts



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