Reliability-Based versus Allowable Stress Design of Foundations for the Center for Missouri ...

125 Pages·2017·4.75 MB·English

Reliability-Based versus Allowable Stress Design of Foundations for the
Center for Missouri Studies Building

A Thesis presented to
the Faculty of the Graduate School
at the University of Missouri-Columbia

In Partial Fulfillment
of the Requirements for the Degree
Master of Science

by
NATHANIEL DUMMERTH

Dr. John J. Bowders, P.E. Thesis Supervisor

DECEMBER 2017
The undersigned, appointed by the dean of the Graduate School, have examined the thesis
entitled
Reliability-Based versus Allowable Stress Design of Foundations for the Center for Missouri
Studies Building

Presented by Nathaniel Dummerth,
a candidate for the degree of Master of Science in Civil Engineering,
and hereby certify that, in their opinion, it is worthy of acceptance.

______________________________________________
Professor John J. Bowders, P.E.

______________________________________________
Professor Brent L. Rosenblad, P.E.

______________________________________________
Professor Francisco Gomez

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Reliability-Based versus Allowable Stress Design of Foundations for the Center for
Missouri Studies Building
Abstract
Uncertainty in design parameters is inherent to the field of geotechnical engineering. Allowable
stress design has conventionally been used for foundation design and accounts for uncertainty in
geotechnical parameters and consequences of failure by assigning a global factor of safety.
Allowable stress design is typically a conservative approach and may result in increased
construction costs. The objective of the thesis is to compare allowable stress design with
reliability-based design of foundations. The secondary objective is to initiate a ‘living’ database
of geotechnical parameters for the University of Missouri – Columbia Campus, which will be
expanded by future graduate students.
A geologic history and site investigation results are presented to characterize subsurface
conditions for the Center for Missouri Studies building in Columbia, Missouri and are entered
into the geotechnical database. The existing foundation system of the Center for Missouri Studies
building is evaluated using allowable stress design methods. The existing foundation system is
reconsidered using reliability-based design. In a reliability-based design, uncertainty is quantified
by evaluating the distribution of geotechnical strength parameters and structural loads. Two
alternative foundation types are also considered.
Reliability-based design was shown to be less conservative than allowable stress design. Both
methods produced safe and reliable results, but foundation costs were reduced by seven (7) to
thirty-five (35) percent when reliability-based design was used. The probability of failure of the
foundations was acceptable from both design methods, but was unnecessarily conservative when
using allowable stress design. A final objective of the thesis is to provide a template for future
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geotechnical engineering students to assemble an interactive geotechnical database and detailed
subsurface profile for the University of Missouri-Columbia Campus. Appropriate use of the
database and increased implementation of reliability-based design can reduce future design and
construction costs of local foundations while assuring acceptable levels of reliability.

iv
Acknowledgements
First and foremost, I would like to thank my advisor Dr. John Bowders for his continuous and
tireless support. Dr. Bowders was the instructor for my first ever course at Mizzou, and has
helped guide me through my undergraduate and graduate careers. His enthusiasm for
geotechnical engineering will continue to inspire me throughout my professional career.
Next, I would like to thank Dr. Brent Rosenblad for serving on my thesis committee and as the
professor for five of my engineering courses at Mizzou. I want to thank Dr. Francisco Gomez for
serving on my thesis committee and his advice throughout the thesis process. I would like to
thank Tanya Harris and Gerald Morgan of MU Campus Facilities for providing access to
Campus geotechnical data. I would also like to thank Dr. Dan Ding for her assistance with
micropile design and Andy Boeckmann for his LRFD advice. I would also like to recognize and
thank my fellow graduate student Ben Shetley for his willingness to provide feedback and
assistance at any time. Many thanks are extended to Mary Ellen Bruce Large from Deep
Foundations Institute and John Wolosick from Hayward Baker for providing detailed
information on up-to-date micropile costs used in industry. Finally, I would like to thank Kent
Richardson from Subsurface Constructors for providing complete plans and cost estimates for
drilled shaft construction.

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Table of Contents
Abstract .......................................................................................................................................... iii
Acknowledgements ......................................................................................................................... v
Table of Contents ........................................................................................................................... vi
List of Figures .............................................................................................................................. viii
List of Tables .................................................................................................................................. x
1.0 Introduction ............................................................................................................................... 1
1.1. Background .......................................................................................................................... 1
1.2. Objectives ............................................................................................................................. 2
1.3. Scope of Work ...................................................................................................................... 2
1.4. Layout of the Thesis ............................................................................................................. 2
2.0 Methods..................................................................................................................................... 4
2.1. Introduction .......................................................................................................................... 4
2.2. Structure Details ................................................................................................................... 4
2.3. Geology ................................................................................................................................ 9
2.4. Subsurface Investigation ...................................................................................................... 9
2.5. Allowable Stress Design – Conventional Method ............................................................. 20
2.5.1. Existing Foundation Design ........................................................................................ 20
2.5.2. Alternative Design 1 .................................................................................................... 23
2.5.3. Alternative Design 2 .................................................................................................... 26
2.6. Load and Resistance Factor Design – Reliability Method ................................................. 31
2.6.1. Spread Footings ........................................................................................................... 34
2.6.2. Drilled Shafts ............................................................................................................... 37
2.6.3. Driven Piles ................................................................................................................. 43
2.6.4. Micropiles .................................................................................................................... 44
2.7. Cost Analysis Method ........................................................................................................ 47
2.8. Summary ............................................................................................................................ 49
3.0 Results ..................................................................................................................................... 50
3.1. Introduction ........................................................................................................................ 50
3.2. Existing Foundation Design ............................................................................................... 50
3.2.1. Allowable Stress Design .............................................................................................. 50
3.2.2. Load and Resistance Factor Design............................................................................. 51
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3.2.3. Cost Analysis ............................................................................................................... 53
3.3. Proposed Alternative Foundation Design 1 ....................................................................... 55
3.3.1. Allowable Stress Design .............................................................................................. 55
3.3.2. Load and Resistance Factor Design............................................................................. 56
3.3.3. Cost Analysis ............................................................................................................... 57
3.4. Proposed Alternative Foundation Design 2 ....................................................................... 58
3.4.1. Allowable Stress Design .............................................................................................. 58
3.4.2. Load and Resistance Factor Design............................................................................. 59
3.4.3. Cost Analysis ............................................................................................................... 60
3.5. Summary ............................................................................................................................ 61
4.0 Discussion ............................................................................................................................... 62
4.1. Introduction ........................................................................................................................ 62
4.2. Existing Foundation – ASD vs. LRFD .............................................................................. 62
4.2.1. Spread Footings ........................................................................................................... 62
4.2.2. Drilled Shafts ............................................................................................................... 65
4.3. Existing Foundation Design vs. Alternative Foundation Designs ..................................... 69
4.3.1. Alternative Design 1 .................................................................................................... 69
4.3.2. Alternative Design 2 .................................................................................................... 70
4.4. Summary ............................................................................................................................ 70
5.0 Conclusions ............................................................................................................................. 72
5.1. Summary ............................................................................................................................ 72
5.2. Conclusions ........................................................................................................................ 72
5.3. Recommendations .............................................................................................................. 74
5.3.1. Practical Implications .................................................................................................. 74
5.3.2. Future Research ........................................................................................................... 75
References ..................................................................................................................................... 77
Appendix A: Boring Logs and Laboratory Test Results .............................................................. 79
Appendix B: gINT Cross-Sections ............................................................................................. 101
Appendix C: Sample Calculations .............................................................................................. 109

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List of Figures
Figure 2-1 – Location of Proposed Center for Missouri Studies Building (Enclosed by Green
Line) ................................................................................................................................................ 6
Figure 2-2 – Borehole Location Plan (Engineering Surveys & Services, 2016) .......................... 11
Figure 2-3 – Summary of Laboratory Test Results for Borings B1-B9 (Engineering Surveys &
Services, 2016) .............................................................................................................................. 14
Figure 2-4 - Summary of Laboratory Test Results for Borings B10-B17 (Engineering Surveys &
Services, 2016) .............................................................................................................................. 15
Figure 2-5 Profile of Material Found in Each Borehole (See Fig. 2-2 for Borehole Locations) .. 16
Figure 2-6 – Key to Symbols Used in gINT Cross-Sections ........................................................ 17
Figure 2-7 – Example West to East Cross-Section (6th St. at the left side of the drawing and 7th
St. at the right side) ....................................................................................................................... 18
Figure 2-8 - Example South to North Cross-Section (Elm St. at the left side of the drawing and
Locust St. at the right side) ........................................................................................................... 19
Figure 2-9 - HP Pile Cross-Section (RW Conklin Steel, 2017) .................................................... 24
Figure 2-10 - Typical Micropile Detail (FHWA, 2005) ............................................................... 29
Figure 2-11 - Resistance Factor, φ, for Bearing Resistance of Shallow Foundation on Rock (Abu
El-Ela et al., 2013) ........................................................................................................................ 36
Figure 2-12 - Test Quantity Modifier as a Function of Number of Measurements (Abu El-Ela et
al., 2013) ....................................................................................................................................... 37
Figure 2-13 - Typical Rock Material Constants, m and s (Loehr et al., 2011b) ........................... 41
Figure 2-14 - Typical Ranges of Geological Strength Index (GSI) of Limestone (Loehr et al.,
2011b) ........................................................................................................................................... 42
Figure 2-15 - Resistance Factor for Unit Tip Resistance of Drilled Shaft in Rock (Loehr et al.,
2011b) ........................................................................................................................................... 43
Figure 4-1 - Resistance Factor, φ, for Bearing Resistance of Shallow Foundation on Rock (Abu
El-Ela et al., 2013) ........................................................................................................................ 64
Figure 4-2 - Resistance Factor for Unit Tip Resistance of Drilled Shaft in Rock (EPG Drilled
Shafts, 2011) ................................................................................................................................. 66
Figure 5-1 – Conceptual Relationship Between Decision Making and Reliability-Based Design
(Gilbert, 2003)............................................................................................................................... 75
Figure A-1 – Borehole Location Plan ........................................................................................... 80
Figure A-2 – Symbols and Terms Used in Boring Logs .............................................................. 81
Figure A-3 – Summary of Laboratory Test Results for Borings B1-B9....................................... 82
Figure A-4 - Summary of Laboratory Test Results for Borings B10-B17 ................................... 83
Figure A-5 – Log of Boring B1 .................................................................................................... 84
Figure A-6 - Log of Boring B2 ..................................................................................................... 85
Figure A-7 - Log of Boring B3 ..................................................................................................... 86
Figure A-8 - Log of Boring B4 ..................................................................................................... 87
Figure A-9 - Log of Boring B5 ..................................................................................................... 88
Figure A-10 - Log of Boring B6 ................................................................................................... 89
Figure A-11 - Log of Boring B7 ................................................................................................... 90
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Figure A-12 - Log of Boring B8 ................................................................................................... 91
Figure A-13 - Log of Boring B9 ................................................................................................... 92
Figure A-14 - Log of Boring B10 ................................................................................................. 93
Figure A-15 - Log of Boring B11 ................................................................................................. 94
Figure A-16 - Log of Boring B12 ................................................................................................. 95
Figure A-17 - Log of Boring B13 ................................................................................................. 96
Figure A-18 - Log of Boring B14 ................................................................................................. 97
Figure A-19 - Log of Boring B15 ................................................................................................. 98
Figure A-20 - Log of Boring B16 ................................................................................................. 99
Figure A-21 - Log of Boring B17 ............................................................................................... 100
Figure B-1 – West to East Cross-Section Showing Borings B4, B17, B5 (6th St. at the left side of
the drawing and 7th St. at the right side) .................................................................................... 102
Figure B-2 - West to East Cross-Section Showing Borings B14, B3, B15, B16 (6th St. at the left
side of the drawing and 7th St. at the right side) ........................................................................ 103
Figure B-3 - West to East Cross-Section Showing Borings B11, B12, B13 (6th St. at the left side
of the drawing and 7th St. at the right side) ................................................................................ 104
Figure B-4 – Diagonal Southwest to Northeast Cross-Section Showing Borings B4, B3, B15,
B13 (Corner of Elm St. and 6th St. at the left side of the drawing) ............................................. 105
Figure B-5 - South to North Cross-Section Showing Borings B4, B11, B9, B8 (Elm St. at the left
side of the drawing and Locust St. at the right side) ................................................................... 106
Figure B-6 - South to North Cross-Section Showing Borings B5, B16, B13 (Elm St. at the left
side of the drawing) .................................................................................................................... 107
Figure B-7 - Diagonal Northwest to Southeast Cross-Section Showing Borings B11, B3, B15, B5
(Corner of Elm St. and 7th St. at the right side of the drawing) ................................................. 108

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List of Tables
Table 2-1 – Drilled Shaft Schedule for Existing Foundation Design (Gouldevans, 2017) ............ 7
Table 2-2 – Spread Footing Schedule for Existing Foundation Design (Gouldevans, 2017)......... 8
Table 2-3 – Summary of RQD Data for Limestone and Shale Sampled at the Center for Missouri
Studies Project Site (Engineering Surveys & Services, 2016) ..................................................... 13
Table 2-4 - Comparison of Structural and Geotechnical Resistance for HP 14x73 Pile .............. 25
Table 2-5- Grout-to-Ground Bond Strengths for Different Soil Types (FHWA, 2005) ............... 30
Table 2-6 - Descriptions of the Strength Limit Load Combinations (FHWA, 2011) ................... 33
Table 2-7 - Recommended Probability of Failure for Different Bridge Types (Abu El-Ela et al.,
2013) ............................................................................................................................................. 33
Table 2-8 - Shape Correction Factor, cf, as a Function of Footing Shape (Abu El-Ela et al., 2013)
....................................................................................................................................................... 35
Table 2-9 - Rock Core Data of Burlington Limestone, Sampled About 1.5 Miles from the Thesis
Site (Gunnink and Kiehne, 2002) ................................................................................................. 38
Table 2-10 - Typical mi Constants for Sedimentary Rocks (Loehr et al., 2011b) ........................ 40
Table 2-11 – Estimated Values of End Resistance for Driven Piles (FHWA, 2016) ................... 44
Table 2-12 - Geotechnical Resistance Factors of Axially Loaded Micropiles (AASHTO, 2010) 46
Table 2-13 - Average Price of Each Item Used in Existing Foundation Design (MoDOT, 2014-
2016) ............................................................................................................................................. 48
Table 2-14 - Average Price of Each Item Used in Alternative Design 1 (MoDOT, 2014-2016) . 48
Table 2-15 - Average Price of Each Item Used in Alternative Design 2 ...................................... 49
Table 3-1 - Existing Foundation Spread Footing Dimensions and Quantities – ASD ................. 51
Table 3-2 - Drilled Shaft Dimensions and Quantities – ASD ....................................................... 51
Table 3-3 - Values Used to Calculate Tip Resistance of Drilled Shafts ....................................... 52
Table 3-4 - Values Used to Calculate Bearing Capacity of Spread Footings ............................... 53
Table 3-5 - Existing Foundation Spread Footing Dimensions and Quantities - LRFD ................ 53
Table 3-6 - Drilled Shaft Dimensions and Quantities - LRFD ..................................................... 53
Table 3-7 - Cost Summary of Existing Foundation Design - ASD .............................................. 54
Table 3-8 - Cost Summary of Existing Foundation Design - LRFD ............................................ 54
Table 3-9 - Alternative Design 1 Pile Cap Dimensions and Quantities - ASD ............................ 55
Table 3-10 - Alternative Design 1 Spread Footing Dimensions and Quantities - LRFD ............. 56
Table 3-11 - Alternative Design 1 Pile Cap Dimensions and Quantities - LRFD ........................ 56
Table 3-12 - Alternative Design 1 Spread Footing Dimensions and Quantities - LRFD ............. 57
Table 3-13 - Cost Summary of Alternative Design 1 - ASD ........................................................ 58
Table 3-14 - Cost Summary of Alternative Design 1 - LRFD ...................................................... 58
Table 3-15 - Dimensions of Micropile Cross-Section - ASD ....................................................... 59
Table 3-16 - Micropile Quantity and Lengths - ASD ................................................................... 59
Table 3-17 - Dimensions of Micropile Cross-Section - LRFD..................................................... 60
Table 3-18 - Micropile Quantities and Lengths - LRFD .............................................................. 60
Table 3-19 - Cost Summary of Alternative Design 2 - ASD ........................................................ 60
Table 3-20 - Cost Summary of Alternative Design 2 - LRFD ...................................................... 61
Table 4-1 - Probability of Failure of Spread Footings for ASD and LRFD Designs ................... 65
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