The Analysis and Design of Rectangular Spread Footing Foundations.

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ABSTRACT

There are many factors to consider when designing a foundation including the bearing capacity of the soil where it rests upon, the factored loads it will bear, and safety factors to consider, its strength to handle shear forces, and the standardized code to ensure its safety. Those factors require careful calculations and the method generally used is trial and error which would most likely consume a lot of time. This project is intended to lessen that time and provide easy access to information for future references to the user (consultant). Theories in this project include the geotechnical and structural aspects of a foundation design and analysis; and software and analysis design methods, using tools such as Data Flow Diagrams, according to R. Pressman. The program created uses Java programming language and MySQL to manage the database used. Finally, the result presented is in the form of a portable document file (pdf) that is viewed, saved, and printed using an external application.

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ABSTRAK

Banyak faktor yang perlu dipertimbangkan ketika merancang sebuah pondasi, diantaranya: daya dukung tanah dimana pondasi tersebut diletakkan, beban terfaktor yang membebani, pertimbangan faktor keamanan, kekuatan fondasi menahan gaya geser yang terjadi, dan kode standar untuk memastikan keamanannya. Faktor-faktor tersebut memerlukan perhitungan yang teliti dan metode yang umumnya digunakan adalah trial and error dimana menghabiskan banyak waktu. Program ini dimaksudkan untuk mengurangi kendala tersebut dan dengan mudah menyediakan informasi yang dapat dijadikan referensi untuk pengguna (konsultan) di masa yang akan datang. Teori-teori yang digunakan untuk menunjang program ini termasuk teori tentang aspek struktural dan geoteknikal dalam mendesain fondasi; dan untuk metode perangkat lunak dan analisis desain menggunakan tools, seperti Data Alir Diagram menurut R. Pressman. Program ini dibuat menggunakan bahasa pemrograman Java dan MySQL untuk mengelola basis data yang digunakan. Hasil yang disajikan dalam bentuk portable document file (pdf) yang dapat dilihat, disimpan, dan diprint dengan aplikasi eksternal.

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TABLE OF FIGURES

Figure 1 Typical footings, (a) Single or spread footings; (b) stepped footing;

(c) sloped footing; (d) wall footing; (e) footing with pedestal. ... 8

Figure 2 Modes of bearing capacity failure: (a) general shear failure; (b) local shear failure; (c) punching shear failure. (Coduto, 2001) ... 9

Figure 3 Typical load-displacement curves for different modes of bearing capacity failure: (a) general shear failure; (b) local shear failure; (c) punching shear failure. (Coduto, 2001) ... 9

Figure 4 Nature of Bearing Capacity Failure in Soil: (a) general shear failure; (b) local shear failure; (c) punching shear failure. (Das, 1999) ... 10

Figure 5 Eccentrically loaded foundations (Das, 1999) ... 14

Figure 6 Foundation of columns with off-center loading (Das, 1999) ... 15

Figure 7 Analysis of foundation with two-way eccentricity (Das, 1999) ... 15

Figure 8 The two modes of shear failure: (a) one-way shear, and (b) two-way shear. (Coduto, 2001). ... 17

Figure 9 Critical Sections and Tributary Areas for Shear in a Spread Footing ... 18

Figure 10 Flexural Action of a Spread Footing ... 20

Figure 11 Definition of A1 and A2 ... 23

Figure 12 Analysis Model Structure ... 26

Figure 13 Design Footing Dimensions Flowchart... 33

Figure 14 One-way Shear Flowchart ... 35

Figure 15 Two-Way Shear Flowchart ... 36

Figure 16 Flexural Reinforcement Flowchart ... 37

Figure 17 Load Transfer Flowchart ... 38

Figure 18 ERD of Foundation Information System... 40

Figure 19 Entity Relationship Table of the ERD of Foundation Information System ... 41

Figure 20 Foundation Information System Data Context Diagram ... 44

Figure 21 DFD Level 1 of Foundation Information System ... 45

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Figure 23 DFD Level 3 Process 2.1: Manage Clients ... 46

Figure 24 DFD Level 3 Process 2.2: Manage Projects ... 47

Figure 25 DFD Level 3 Process 2.3: Manage Soil ... 48

Figure 26 DFD Level 3 Process 2.4: Manage Reinforcement ... 48

Figure 27 DFD Level 2 Process: Create New Data ... 49

Figure 28 DFD Level 3 Process 3.1: New Project ... 50

Figure 29 DFD Level 3 Process 3.2: Open Project ... 51

Figure 30 DFD Level 4 Process 3.2.2: Open Foundation ... 52

Figure 31 UID for Login ... 69

Figure 32 UID for Foundation Information System Frame: Start Menu ... 69

Figure 33 UID for Foundation Information System Frame: Edit Menu ... 70

Figure 34 UID for New Project Frame ... 71

Figure 35 UID for Project Manager ... 72

Figure 36 UID for Foundation Design ... 73

Figure 37 UID for Calculating Dimension of Spread Footing ... 74

Figure 38 UID for Calculating Load Transfer ... 74

Figure 39 UID for Calculating Flexure Footing Reinforcements ... 75

Figure 40 UID for Calculating Shrinkage Reinforcements ... 75

Figure 41 UID for Displaying the Report ... 76

Figure 42 UID for Clients Frame ... 76

Figure 43 UID for Projects Frame ... 77

Figure 44 UID for Soil Frame ... 77

Figure 45 UID for Reinforcements Frame ... 78

Figure 46 Display of Login to the System ... 79

Figure 47 New Project Form ... 80

Figure 48 Search Client ... 80

Figure 49 Search Soil Data ... 81

Figure 50 Project Manager ... 82

Figure 51 Add New Foundation ... 82

Figure 52 Foundation Design Frame ... 83

Figure 53 Calculate Dimension Frame ... 84

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Figure 55 Flexure Footing Reinforcements Frame... 85

Figure 56 Shrinkage Footing Reinforcements Frame ... 86

Figure 57 Client Frame ... 87

Figure 58 Soil Frame ... 88

Figure 59 Reinforcements Frame ... 89

Figure 60 Edit Project ... 90

Figure 61 Application's Calculation Results ... 99

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TABLE OF TABLES

Table I Terzaghi's Bearing Capacity Factors ... 12

Table II Values of Safety Factor Used (Bowles, 1988) ... 16

Table III Symbols in an ERD ... 27

Table IV DFD Symbols and Functions ... 28

Table V Notations of Content Description ... 30

Table VI Client Entity Table ... 42

Table VII Foundation Entity Table ... 42

Table VIII Project Entity Table... 43

Table IX Soil Entity Table ... 43

Table X Reinforcement Entity Table ... 44

Table XI PSPEC Process 1: Login ... 53

Table XII PSPEC Process 2.1.1: Save Data CLient ... 53

Table XIII PSPEC Process 2.1.2: Delete Data Client ... 54

Table XIV PSPEC Process 2.2.1: Save Project ... 54

Table XV PSPEC Process 2.2.2: Delete Project ... 55

Table XVI PSPEC Process 2.3.1: Save Soil ... 55

Table XVII PSPEC Process 2.3.2: Delete Soil ... 56

Table XVIII PSPEC Process 2.3.3: Create Soil ... 56

Table XIX PSPEC Process 2.4.1: Save Reinforcement ... 57

Table XX PSPEC Process 2.4.2: Delete Reinforcement ... 57

Table XXI PSPEC Process 2.4.3: Create Reinforcement ... 57

Table XXII PSPEC Process 3.1.1: Search CLient ... 58

Table XXIII PSPEC Process 3.1.4: Search Soil ... 58

Table XXIV PSPEC Process 3.1.5: OK (Save Project) ... 59

Table XXV PSPEC Process 3.2.1: Add New Foundation ... 59

Table XXVI PSPEC Process 3.2.3: Delete Foundation ... 60

Table XXVII PSPEC Process 3.2.2.1: Run Calculations Determine Dimension of Spread Footing ... 60

Table XXVIII PSPEC Process 3.2.2.2: Calculate Load Transfer ... 61

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Table XXX PSPEC Process 3.2.2.4: Calculate Shrinkage Reinforcements . 62

Table XXXI PSPEC Process 3.2.2.5: Create Report ... 62

Table XXXII Data Dictionary of Data_Client ... 63

Table XXXIII Data Dictionary of Data_Login ... 63

Table XXXIV Data Dictionary of Data_Soil ... 64

Table XXXV Data Dictionary of Data_Project ... 64

Table XXXVI Data Dictionary of Data_Foundation ... 64

Table XXXVII Data Dictionary of Data_Reinforcement ... 67

Table XXXVIII Data Dictionary of List_Reinforcement ... 67

Table XXXIX Data Dictionary of List_Client ... 67

Table XL Data Dictionary of List_Project ... 68

Table XLI Data Dictionary of List_Soil ... 68

Table XLII Data Dictionary of Detailed Drawing ... 68

Table XLIII Data Dictionary of Design Result ... 68

Table XLIV Soil Data of RSGM-UKM ... 91

Table XLV Data Summary of Foundation Analysis and Design ... 92

Table XLVI Login Test ... 100

Table XLVII Create New Project Test ... 101

Table XLVIII Project Manager Test ... 101

Table XLIX Foundation Design Test ... 102

Table L Manage Client Data Test ... 103

Table LI Edit Project Data Test ... 103

Table LII Manage Soil Data ... 104

Table LIII Manage Reinforcements Data ... 105

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TABLE OF NOTATIONS

The terms in the list are used in this report in the order of their appearance:

c = the cohesion of soil

φ = internal friction of soil

Df = depth of the ground where the foundation rests upon

q = bearing capacity

qult = ultimate net bearing capacity

qa = allowable bearing capacity

Nq, Nc, Nγ = bearing capacity factors

sc, sγ = shape factors

B = least lateral base dimension L = greatest lateral base dimension Pu = factored normal load

Pn = nominal normal load capacity

Φ = 0.75; resistance factor

e = eccentricity of load

Vu = factored shear force on critical surface, N

Vc = nominal shear capacity on the critical surface, N

Vn = nominal shear strength, N

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fy = specified yield strength of reinforcement, MPa

= the ratio of the column’s longest length to the column’s shorter

= constant used to compute Vc in slabs and footings (center = 40, edge = 30, corner = 20)

= reinforcement ratio

A = area specified, mm2

d = diameter of reinforcement specified, mm

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ABOUT THE AUTHOR

Name : Fiona Hidayani Dwiningrum

Gender : Female

Location of Birth : Bandung

Date of Birth : 22 February 1990 2004 – 2005 Edison High School (Magnet Program), Fresno, CA,

USA

2005 – 2006 SMA Bopkri I, Jogjakarta

2006 – 2008 Global Prestasi National School, Bekasi

2008 – Now Double Degree Program (Information System – Civil Engineering) Maranatha Christian University

Work History

2008 – Now Freelance musician (violist) in Sinfonia Bandung 2011 – 2012 Part-time librarian at the library of MCU

Experiences and Achievements

1999 – 2001 Member of the school’s safety officer program 2002 – 2003 Class representative of the student council

2002 – 2003 Member of the Math-O-Rama, won 2nd place as a group 2006 Won 1st place as a group in a Mading Competition 2008 Won 2nd place in an English Article competition from

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CHAPTER I INTRODUCTIONS

1.1 Background

All structures need a solid foundation in order to stand. The most important function of a foundation is its ability to support the weight of the structure above no matter the size. There are two major types of foundations: shallow foundation and deep foundations. Shallow foundations, particularly rectangular spread footings, are used mostly for small buildings such as a house with no more than three stories high and on good soil such as rock. Deep foundations are used when the load it bears (the structure load above) is great and the soil is poor like soft clay.

Both types require accurate calculations of dimensions, stability, and strength in order to serve their purpose based on the standards already set. There are several methods to calculate and analyze the essentials of a foundation. Specifically there are two major design aspects: geotechnical and structural. The geotechnical aspect of the design is concentrated on the parameters and behaviors of soil; while the

structural aspect is concentrated on the characteristics of the design’s

structure and whether or not it meets the safety standards applied. Because in general, concrete is used as the material for constructing a foundation, the structural design of it would be based on the characteristics of concrete and the codes that govern them.

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1.2 Problems Formulated

1. What calculations are needed to design a rectangular spread footing foundation?

2. What controls are used for the design of a rectangular spread footing foundation?

3. What materials are used in constructing a foundation and what kind of structural failures need to be anticipated and with what?

4. How does a foundation designer design a foundation, requested by a building owner, in a more efficient and effective way?

5. Does putting calculations concerning the design of a foundation in a program help speed up the process of designing it? How does it help speed up the process?

6. If an information system were able to calculate a foundation’s

design, how will it present it as a report to the owner?

7. What information will the information system keep regarding a

foundation’s design?

8. What is the use of keeping a database of foundations?

1.3 Purpose

1. The main function of the program is to calculate both the geotechnical factors and structural reinforcements of the foundations.

2. The controls used to ensure the safety of a foundation will be determined by the standard codes that are currently being used. 3. A foundation is generally made of concrete with reinforcements of

steel to anticipate flexural and shrinkage failure of the concrete itself as well as steel dowels to transfer the load from the column to the footing.

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calculate a foundation’s essentials. It will also keep data that will

help future designs and analysis of foundations.

5. Calculating using a computer application will certainly speed up the process of any calculation work including calculating the details and measurements of a foundation by automatically computing input data from the user, processing it according to the steps required, and finally giving output that is easy to read and understand.

6. The final result of a foundation design should be represented as a carefully drawn detail of the foundation with its measurements to scale and important calculation results for considerations in field constructions.

7. The information system will keep information regarding a foundation such as the owner requesting the design, the building which will stand upon it, the soil on which it will rest, the dimensions of its reinforcements, and the location and address where it will be built. 8. Keeping records of past designs is very useful in future

developments and those records can also be used as a guarantee or proof of the correct design of the foundation.

1.4 Scope of Research

Topics to be discussed: 1. Definition of foundation

2. Theories on shallow foundation structures. More specifically, concrete rectangular spread footing foundations

3. Theories of calculation of foundations methods using data from laboratory experiment

4. Formulas and equations for analyzing foundations (Terzaghi Method)

5. Structural behavior of the foundation, as well as its calculations, formulas, and equations

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8. Excluding settlement analysis of foundation 9. Excluding calculations for top structure

10. Excluding calculations of bearing capacity with water tables 11. Using the information system

12. Creating, editing, deleting, and saving data (client, soil project, reinforcement)

13. Calculating and designing the dimensions, flexural and shrinkage reinforcements, and dowels of the foundation

14. Making a report and displaying it as a portable document file. 15. Drawing a diagram with Java2D

The case that will be modeled after for this research is based on what a consultant would do when an owner presents him/her with a project. Foundations designed for the project is strictly limited to the rectangular spread footing model which will be designed for a range of loads for economical purposes as is the case in a normal project situation. The structure on top is limited to a 3 (three) story building with loads that will not exceed the capacity of a shallow foundation. Soil data from laboratory tests is given by the owner to the consultant for further analysis and designs. As a result of the design, a report in the form of a detailed drawing of the finished foundation will be shown to the owner.

1.5 Data Source

1. Structural data is from a previous concrete lab report. 2. ACI-318-05M (American Concrete Institute standard code).

3. Theory on designing a foundation is from books and e-books recommended by the supervising Civil Engineer lecturers.

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1.6 Presentation System

This report is divided into three parts: the beginning, content, and ending. The beginning consists of the following:

a. Title page

b. Legalization page c. Preface

d. Publication Agreement page e. Statement of Originality f. Abstract

g. Table of Contents h. Appendixes

The content of this report consists of 5 chapters: Chapter 1 INTRODUCTION

Chapter 1 covers the introduction of the manuscript, purpose and reasoning, scope of research, and the arrangement of the writing.

Chapter 2 THEORIES

Chapter 2 explains the basic theories of Foundation, soil bearing capacity according to Terzaghi, and computations based on the American Concrete Institute (ACI) code. It also explains the theory of structural behavior found in concrete foundations. This chapter will also explain what an information system is and other basic theories to support this project.

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Chapter 3 is where the information system is analyzed and designed; and it is where the flowchart used in the design is tested.

Chapter 4 IMPLEMENTATION

Chapter 4 will describe the implementation of the user interface Chapter 5 EVALUATION

This chapter will present the testing results of the information system and results of a questionnaire made to evaluate the user interface. The last part of this report is:

Chapter 6 CONCLUSION

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CHAPTER VI CONCLUSION AND

CONJECTURE

6.1 Conclusions

1. Terzaghi’s bearing capacity is used in designing a spread footing foundation. For the shape factors a ratio of length per width of foundation is put into consideration. The value of N_γis calculated without dependency on to simplify calculations using a computer. The bearing capacity of a finished foundation does also put into consideration the possible shear failure of the soil it rests upon. More specifically, the punching shear.

2. Part of designing a foundation is the control. The ACI (SNI for Indonesia) is used to ensure the design’s safety. More specifically, ACI chapters 15 of spread footing foundations and chapter 11 for shear strength calculations.

3. Reinforced concrete is generally used when constructing a rectangular spread footing foundation. The reinforcement is used for bending

actions that might occur in the foundation’s structure. Shrinkage

reinforcements are used and designed according to the minimum ratio. Transferring load from the column to the footing is done by adding dowels (minimum number of dowels is 4).

4. By using an application such as the Foundation Information System, a foundation designer can calculate the dimensions of a foundation and its controls faster and easier.

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109 6. The Foundation Information System presents its calculation results in a text form explaining the numbers of important values and its effect on the design. A drawing of the finished foundation complete with its dimensions is also presented.

7. The information kept in the system is a consultant’s client, project, and foundation designs and soil data associated with it.

8. By keeping a database of foundations, the consultant is able to view past foundation designs for future references.

6.2 Conjecture

1. Theory of designing a foundation is always applied but not always executed in the field. Experience is always prioritized in the design of a foundation.

2. The application should offer a more organized report of a project and its foundation designs.

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Bibliography

American Concrete Institute Committee, 3. S. (2005). Building Code Requirements For Structural Concrete and Commentary (ACI

318M-05). American Concrete Institute.

Bowles, J. E. (1988). Foundation Analysis and Design (4th Edition ed.). Singapore: McGraw Hill.

Budhu, M. (2000). Soil Mechanics and Foundations. New York: John Wiley & Sons Inc.

Coduto, D. P. (2001). Foundation Design Principles and Practices. Upper Saddle River, New Jersey, United States of America: Prentice-Hall Inc.

Das, B. M. (1999). Principles of Foundation Engineering (4th ed.). Pacific Grove, California, United States of America: PWS Publishing.

MacGregor. (2005). Reinforced Concrete: Mechanics and Design (4th ed.). Upper Saddle River, New Jersey, United States of America: Pearson Prentice Hall.

Pressman, R. S. (2001). Software Engineering: A Practitioner's Approach (5th ed.). New York, New York, United States of America: McGraw-Hill .

Shelly, G. B., Cashman, T. J., & Rosenblatt, H. J. (2006). Systems Analysis and Design (6th ed.). Boston, Massachusettes, United States of

America: Thomson Course Technology.