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UNIVERSITY OF ILLINOIS
ENGINEERING EXPERIMENT STATION
BULLETIN No. 56 MARCH 1912
TESTS OF COLUMNS: AN INVESTIGATION OF THE
VALUE OF CONCRETE AS REINFORCEMENT FOR
STRUCTURAL STEEL COLUMNS
BY ARTHUR N. TALBOT, PROFESSOR OF MUNICIPAL AND SANITARY
ENGINEERING AND IN CHARGE OF THEORETICAL AND APPLIED
MECHANICS, AND ARTHUR R. LORD, RESEARCH FELLOW IN
THEORETICAL AND APPLIED MECHANICS
CONTENTS
I. INTRODUCTION
PAGE
1. P relim inary ............... . ........... ............. 3
2. Scope of Bulletin......... .... . . ....... . 4
3. Acknowledgment................................... 5
II. MATERIALS, TEST PIECES, AND METHODS OF TESTING
4. The Steel Columns.......... . . ................. 5
5. Sections of Columns.................... ............. 6
6. Cement and Aggregates .......... ................ 7
7. Concrete......................... ... .. ............. 7
8. M aking of Columns.................................. 8
9. Auxiliary Test Specimens............... ............ . 9
10. Storage and Handling......... ..... ............... 10
11. Method of Measuring Deformations.................... 11
12. M ethod of Testing................. ....... .. ...... . 12
III. EXPERIMENTAL DATA AND DISCUSSION
13 . D ata ................ ............ .. ............... 17
A. PLAIN STEEL COLUMNS-EFFECT OF LENGTH
14. Phenomena of the Tests ...................... . .. 17
15. Stress-deformation Relations.............. ........ . 18
16. Relation of Strength to Length...... .................. 19
B. CORE TYPE-EFFECT OF LENGTH
17. Phenomena of the Tests ........................ . . 23
18. Stress-deformation Relations.................. ....... 25
19. Effect of Test Conditions........................ . . 25
20. Effect of Length.................................. 25
21. Comparison with Plain Steel Columns.................. 27

C. CORE TYPE-VALUE OF CONCRETE 22. Test Phenomena and Stress-deformation Relations for Various Mixtures..... ................. .......... 28 23. Basis for Determining Load Taken by Concrete....... 28 24. Development and Amount of Concrete Stress .......... 29 25. Comparison of Cube and Cylinder Strength with Column Strength........................ ..... ........... 31 26. Values of E and n .... ............................. 32 D. FIREPROOFED COLUMNS 27. Phenomena of the Tests ............................. 34 28. Stress-deformation Relations.................. ...... 35 29. Comparison of Concrete Stresses on Gross Section and on Core Section ................................... 35 30. Permissible Deformation as Governing Design......... 37 31. Need of a Tie to Prevent Stripping of Shell............ 37 E. SPIRALED COLUMNS 32. Phenomena of Tests and Stress-deformation Relations.. 37 33. Effect of Spiral............................ ......... 40 34. Availability of Spiral Strength for Design. ............ 42 F. SUMMARY 35. General Comments...................... ........... 42 LIST OF TABLES Page 1. Tensile Strength of Cem ent ............................. .................. . ............ 6 2. Proportionsof Concrete Ingredients...................................................... 8 3. Compression Tests of Cubes and Cylinders.................................. .............. 10 4. Gauge Lengths and Precision of Measurements............................................ 11 5. D ata of Test Colum ns......................................................... .............. 14 6. Maximum Loads Carried by Columns and by Steel and Concrete............. ............ 15 7. Loads Carried at Various Unit-deformations.............................................. 16 8. M oduli of E lasticity. ............ ....... ... .......... ........................ ....... ... 22 9. Average Strength of Specimens and Values of n.................... .................. 33 10. Stress in Concrete in Shell and in Core..................................................... 35 LIST OF FIGURES 1. Details of Test Colum ns...................... ....... .. ... ... ............................. 4 2. View of Bearing Block and Attachment of Instruments................................... 16 3. View Showing Core Type of Column beyond the Maximum Load......................... 16 4. View Showing Fireproofed Column beyond the Maximum Load.......................... 17 5. View Showing Spiraled Column after Test....................... ................ ....... 17 6. Load-deformation Diagrams for Plain Steel Columns ..................................... 18 7. Average Deformation Diagrams for Plain Steel Columns of Various Lengths ........... 19 ,8. Load-length Diagrams for Plain Steel Columns............ ............................... 20 9. Value of Terms in Straight-line Formula for Plain Steel Columns......................... 20 10. Column Formulas for Maximum Load.............................. ...................... 21 11. Load-deformation Diagrams for Core Type of Column ............ ....................... 24 12. Load-length Diagrams for Core Type of Column.......... ........................ 26 13, Value of Terms in Straight-line Formula for Core Type of Column..................... 26 14. Load-length Diagram in Terms of the Steel Section for Core Type of Column .......... 27 15. Load-deformation Diagrams for Columns with Lean and Rich Concrete ................ 28 16. Comparison of Stress-deformations in Column Concrete and in Cylinders................ 30 17. Comparison of Strength of Concrete in Cubes. Cylinders and Columns.. ............... 32 18. Load-deformation Diagrams for Fireproofed Columns..... ...................... ....... 34 19. Load-deformation Diagrams for Spiraled Columns,-First Test.......................... 36 '.20. Load-deformation Diagrams for Spiraled Columns,-Second and Third Tests .. ......... 38

C. CORE TYPE-VALUE OF CONCRETE 22. Test Phenomena and Stress-deformation Relations for Various Mixtures..... ................. .......... 28 23. Basis for Determining Load Taken by Concrete....... 28 24. Development and Amount of Concrete Stress .......... 29 25. Comparison of Cube and Cylinder Strength with Column Strength........................ ..... ........... 31 26. Values of E and n .... ............................. 32 D. FIREPROOFED COLUMNS 27. Phenomena of the Tests ............................. 34 28. Stress-deformation Relations.................. ...... 35 29. Comparison of Concrete Stresses on Gross Section and on Core Section ................................... 35 30. Permissible Deformation as Governing Design......... 37 31. Need of a Tie to Prevent Stripping of Shell............ 37 E. SPIRALED COLUMNS 32. Phenomena of Tests and Stress-deformation Relations.. 37 33. Effect of Spiral............................ ......... 40 34. Availability of Spiral Strength for Design. ............ 42 F. SUMMARY 35. General Comments...................... ........... 42 LIST OF TABLES Page 1. Tensile Strength of Cem ent ............................. .................. . ............ 6 2. Proportionsof Concrete Ingredients...................................................... 8 3. Compression Tests of Cubes and Cylinders.................................. .............. 10 4. Gauge Lengths and Precision of Measurements............................................ 11 5. D ata of Test Colum ns......................................................... .............. 14 6. Maximum Loads Carried by Columns and by Steel and Concrete............. ............ 15 7. Loads Carried at Various Unit-deformations.............................................. 16 8. M oduli of E lasticity. ............ ....... ... .......... ........................ ....... ... 22 9. Average Strength of Specimens and Values of n.................... .................. 33 10. Stress in Concrete in Shell and in Core..................................................... 35 LIST OF FIGURES 1. Details of Test Colum ns...................... ....... .. ... ... ............................. 4 2. View of Bearing Block and Attachment of Instruments................................... 16 3. View Showing Core Type of Column beyond the Maximum Load......................... 16 4. View Showing Fireproofed Column beyond the Maximum Load.......................... 17 5. View Showing Spiraled Column after Test....................... ................ ....... 17 6. Load-deformation Diagrams for Plain Steel Columns ..................................... 18 7. Average Deformation Diagrams for Plain Steel Columns of Various Lengths ........... 19 ,8. Load-length Diagrams for Plain Steel Columns............ ............................... 20 9. Value of Terms in Straight-line Formula for Plain Steel Columns......................... 20 10. Column Formulas for Maximum Load.............................. ...................... 21 11. Load-deformation Diagrams for Core Type of Column ............ ....................... 24 12. Load-length Diagrams for Core Type of Column.......... ........................ 26 13, Value of Terms in Straight-line Formula for Core Type of Column..................... 26 14. Load-length Diagram in Terms of the Steel Section for Core Type of Column .......... 27 15. Load-deformation Diagrams for Columns with Lean and Rich Concrete ................ 28 16. Comparison of Stress-deformations in Column Concrete and in Cylinders................ 30 17. Comparison of Strength of Concrete in Cubes. Cylinders and Columns.. ............... 32 18. Load-deformation Diagrams for Fireproofed Columns..... ...................... ....... 34 19. Load-deformation Diagrams for Spiraled Columns,-First Test.......................... 36 '.20. Load-deformation Diagrams for Spiraled Columns,-Second and Third Tests .. ......... 38

C. CORE TYPE-VALUE OF CONCRETE 22. Test Phenomena and Stress-deformation Relations for Various Mixtures..... ................. .......... 28 23. Basis for Determining Load Taken by Concrete....... 28 24. Development and Amount of Concrete Stress .......... 29 25. Comparison of Cube and Cylinder Strength with Column Strength........................ ..... ........... 31 26. Values of E and n .... ............................. 32 D. FIREPROOFED COLUMNS 27. Phenomena of the Tests ............................. 34 28. Stress-deformation Relations.................. ...... 35 29. Comparison of Concrete Stresses on Gross Section and on Core Section ................................... 35 30. Permissible Deformation as Governing Design......... 37 31. Need of a Tie to Prevent Stripping of Shell............ 37 E. SPIRALED COLUMNS 32. Phenomena of Tests and Stress-deformation Relations.. 37 33. Effect of Spiral............................ ......... 40 34. Availability of Spiral Strength for Design. ............ 42 F. SUMMARY 35. General Comments...................... ........... 42 LIST OF TABLES Page 1. Tensile Strength of Cem ent ............................. .................. . ............ 6 2. Proportionsof Concrete Ingredients...................................................... 8 3. Compression Tests of Cubes and Cylinders.................................. .............. 10 4. Gauge Lengths and Precision of Measurements............................................ 11 5. D ata of Test Colum ns......................................................... .............. 14 6. Maximum Loads Carried by Columns and by Steel and Concrete............. ............ 15 7. Loads Carried at Various Unit-deformations.............................................. 16 8. M oduli of E lasticity. ............ ....... ... .......... ........................ ....... ... 22 9. Average Strength of Specimens and Values of n.................... .................. 33 10. Stress in Concrete in Shell and in Core..................................................... 35 LIST OF FIGURES 1. Details of Test Colum ns...................... ....... .. ... ... ............................. 4 2. View of Bearing Block and Attachment of Instruments................................... 16 3. View Showing Core Type of Column beyond the Maximum Load......................... 16 4. View Showing Fireproofed Column beyond the Maximum Load.......................... 17 5. View Showing Spiraled Column after Test....................... ................ ....... 17 6. Load-deformation Diagrams for Plain Steel Columns ..................................... 18 7. Average Deformation Diagrams for Plain Steel Columns of Various Lengths ........... 19 ,8. Load-length Diagrams for Plain Steel Columns............ ............................... 20 9. Value of Terms in Straight-line Formula for Plain Steel Columns......................... 20 10. Column Formulas for Maximum Load.............................. ...................... 21 11. Load-deformation Diagrams for Core Type of Column ............ ....................... 24 12. Load-length Diagrams for Core Type of Column.......... ........................ 26 13, Value of Terms in Straight-line Formula for Core Type of Column..................... 26 14. Load-length Diagram in Terms of the Steel Section for Core Type of Column .......... 27 15. Load-deformation Diagrams for Columns with Lean and Rich Concrete ................ 28 16. Comparison of Stress-deformations in Column Concrete and in Cylinders................ 30 17. Comparison of Strength of Concrete in Cubes. Cylinders and Columns.. ............... 32 18. Load-deformation Diagrams for Fireproofed Columns..... ...................... ....... 34 19. Load-deformation Diagrams for Spiraled Columns,-First Test.......................... 36 '.20. Load-deformation Diagrams for Spiraled Columns,-Second and Third Tests .. ......... 38