Alternative Support Systems for Cantilever - National Transportation ...

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would be useful to determine the equivalent torsional strength from concrete breakout and design the rest of the test to preclude other failure modes. In order to calculate an estimated strength of the concrete breakout, the anchor breakout equations need to be modified to account for the differences between an anchor breakout and the pipe and plate breakout. Figure 3-1. Concrete breakout of an anchor caused by shear directed parallel to the edge for a cylindrical foundation An anchor breakout failure occurs at the surface of the concrete in which it is installed, typically with a ≈35° breakout failure cone. The embedded pipe and stiffener configuration would cause the stiffeners to cause a similar ≈35° breakout failure cone, though not at the top of the shaft. The breakout would occur where the plates are embedded in the concrete. As a result of this expected concrete breakout, the breakout surface would be considerably larger than that of a typical concrete breakout for an anchor loaded in shear because it will create a breakout cone in both the top and bottom of the welded plate. Figure 3-2 depicts the differences between the typical anchor concrete breakout and the expected breakout caused by the welded plates. In order to quantify the difference in these breakout configurations, some manipulation of the governing equations for concrete breakout of an anchor loaded in shear from ACI 318-08 Appendix D (5) will be required. First, the breakout strength of an anchor loaded in shear needs to be described. The basic breakout strength of a single anchor in cracked concrete loaded in shear perpendicular to an edge (See Figure 3-3) is described in ACI 318-08 Equation D-24 and is shown below as Equation 3-1 (5). 24
Figure 3-2. Differences between concrete breakout failures for anchor bolts in shear and embedded pipe and plate section in torsion ( ) 5 . 1 0. 2 ⎛ e V ⎜ ⎛ l ⎞ b = 7 ⎜ ⎜ d ⎟ a ⎝ ⎝ ⎠ Where ⎞ d ⎟ a λ ⎟ ⎠ f ′ c ca1 (3-1) Vb = basic concrete breakout strength in shear of a single anchor in cracked concrete (lb.) = load bearing length of anchor for shear (in.) l e =hef < 8 da da = outside diameter of anchor (in.) λ = 1.0 for normal weight concrete f’c = specified compressive strength of concrete (psi) ca1 = distance from the center of an anchor shaft to the edge of concrete taken in the direction of the applied shear (in.) Vb 25 ca1 Concrete Edge Figure 3-3. Concrete breakout formula for an anchor loaded in shear 1 le Vb
Page 1 and 2: Report No. BDK75 977-04 Date: Augus
Page 3 and 4: Metric Conversion Table SYMBOL WHEN
Page 5 and 6: ALTERNATIVE SUPPORT SYSTEMS FOR CAN
Page 7 and 8: EXECUTIVE SUMMARY During the 2004 h
Page 9 and 10: CHAPTER TABLE OF CONTENTS 1 INTRODU
Page 11 and 12: Torsion Test Data .................
Page 13 and 14: LIST OF FIGURES Figure page Figure
Page 15 and 16: Figure 4-15. Arrangement of the LVD
Page 17 and 18: CHAPTER 1 INTRODUCTION This project
Page 19 and 20: CHAPTER 2 BACKGROUND The following
Page 21 and 22: information obtained in the late 19
Page 23 and 24: these problems. The concern with fa
Page 25 and 26: opposite side, see Figure 2-2 The s
Page 27 and 28: 2.2.4 Helical Pipes This option wou
Page 29 and 30: 2.3 Alternative Foundations from Ot
Page 31 and 32: Figure 2-10. Drilled concrete piles
Page 33 and 34: Figure 2-13. Grouted soil anchors G
Page 35 and 36: The pad and pier foundation, found
Page 37 and 38: comments and recommendations on pre
Page 39: CHAPTER 3 DESIGN IMPLICATIONS Based
Page 43 and 44: 2 [ ] 2 2 ( r ) + 3. 25 ( r ) − (
Page 45 and 46: eakout surface for a single plate,
Page 47 and 48: strength of a headed anchor in tens
Page 49 and 50: Figure 3-9. Schematic of anticipate
Page 51 and 52: Vbfp l e tfp bfp f’c ca1 = the ba
Page 53 and 54: 3.2.2 Equivalent Side-Face Blowout
Page 55 and 56: computed. See Equation 3-14 below t
Page 57 and 58: One method to quantify the failure
Page 59 and 60: • An additional 12-4.5” long, 1
Page 61 and 62: Applied load Lever arm Figure 4-4.
Page 63 and 64: Figure 4-8. Isometric view of embed
Page 65 and 66: Flexural plate breakout area Torsio
Page 67 and 68: 4.2.4 Annular Base Plate Design The
Page 69 and 70: torsional strength of the lever arm
Page 71 and 72: 4.4 Concrete Block and Tie-Down Des
Page 73 and 74: Figure 4-13. Arrangement of the LVD
Page 75 and 76: 4.7 Summary of Torsion and Flexure
Page 77 and 78: foundation displayed the predicted
Page 79 and 80: Figure 5-5. Specimen at failure 5.1
Page 81 and 82: Figure 5-7. Torsional moment and ro
Page 83 and 84: torsional 45 degree crack formation
Page 85 and 86: Figure 5-11. Widening of concrete b
Page 87 and 88: Failure cracks widen Bond loosens F
Page 89 and 90: Rear of shaft Figure 5-14. Load and
Page 91 and 92:
testing, signifying that the predic
Page 93 and 94:
provided in NCHRP Report 412 were i
Page 95 and 96:
6.2.2 Tapered Embedded Steel Pipe a
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Figure 6-3. FDOT Design Standards I
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This option provides a possible alt
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6.2.5 Cast-in-Place Solid Concrete
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This option does have some disadvan
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Figure 6-9. Embedded steel pipe and
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However, the fillet welds are susce
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APPENDIX A TEST APPARATUS DRAWINGS
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Figure A-3. Dimensioned side elevat
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Figure A-5. Dimensioned drawings of
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Figure A-7. Dimensioned plan drawin
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Figure A-9. Dimensioned drawing of
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Figure A-11. Dimensioned view of em
Page 121 and 122:
STIFFENER DESIGN Calculation of Cap
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L breakout Concrete Breakout Equiva
Page 125 and 126:
Abrg L⋅b 7 in 2 := = .5 Nsb 200
Page 127 and 128:
β 1 f c Calculations Using ACI Str
Page 129 and 130:
Determine Flexural Capacity of Roun
Page 131 and 132:
DEVELOPMENT LENGTHS OF FLEXURAL REI
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Short Pipe Design Flexural Strength
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Long Pipe Design Flexural Strength
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Superstructure Assembly Strength -
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Weld Design Tn_blowout Vweld := Tor
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Check_Bolt_Shear := "Sufficient Str
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Check Reinforcement No_Bars_Block_R
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Tie-Down Design Block Properties Wi
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Vmax Total Load that the Tie-down m
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λpf := .38⋅ λpw := 3.76⋅ E F
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Input and Properties Shaft Torsion
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ψcV := 1.4 ψecV := 1.0 ψedV := 1
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lbreakout := L + 2⋅1.5ca1 lbreako
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Rn_weld := Throat⋅FW Rn_weld 11.1
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⎛ ⎜ ⎜⎜⎜⎜⎜⎜⎜ 9.250
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Flexural Capacity of T-Plates Using
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FAILURE EQUATIONS Torsion Threshold
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Required Length of Shaft Based on B
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Design Axial Strength ϕcomp := .90
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Design Axial Strength ϕcomp := .90
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Zp := ⎛ ⎜ ⎝ bp tp⋅ 2 ⎞
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Bolt Properties - D1" ASTM A325 Cen
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CONCRETE BLOCK Concrete Block Desig
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Check Shear Check_Shear_B := "Suffi
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7'-4" 8" 5'-4" 8" 1'-3" Calculate s
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Required Capacity of the Channel As
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Check_Flange_Compact_Unit := "Compa
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Rear of Shaft Face of Shaft Figure
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Bolt slippage ends Predicted failur
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APPENDIX D DESIGN GUIDELINES For th
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The designer should then use this i
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• Determine the angle required fo
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Superstructure Base Connection Foun
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1.5ca1 1.5ca1 Length of bearing are
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Vu = 9.04 kip T .u = 198.88 ft·kip
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Increase threaded rod diameter to 2
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Embedded Pipe and Torsion Plates De
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⎝ ⎠ Check_Breakout_Torsion := "
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Lbreakout := tflex.plate + 2⋅1.5c
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( ) .85 if fc < 4000psi β 1 f c .6
Page 211 and 212:
REFERENCES 1. Cook, R.A., and Halco
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