Alternative Support Systems for Cantilever - National Transportation ...

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Figure 6-8. Embedded steel pipe and hoops with grouted slip base connection may not be viable to connect to the steel horizontal member. This connection may also be more difficult to monitor or repair than a visible connection. following: Tapered concrete monopole “sleeve” Grout Grout seal Design strength considerations for this connection include, but are not limited to, the • Breakout strength (of embedded section on concrete foundation) • Grout strength • Torsional strength • Flexural strength • Monopole to horizontal member connection 6.2.8 Embedded Steel Pipe and Plates with Bolted Plate Connection In this option, an annular plate would be welded to both the monopole and the stub of the embedded steel pipe protruding from the foundation. The two annular plates would be bolted together, allowing for space between for leveling nuts to be used. The leveling nuts would make it easier to ensure the monopole was erected properly. See Figure 6-9 for the connection setup. 88 Steel HSS pipe with welded rebar hoops and plates Concrete foundation
Figure 6-9. Embedded steel pipe and plates with bolted plate connection One benefit with this connection is that it would be easy to construct and the materials would be easy to obtain. Since this option is very similar to the current base plate and anchor bolt option, it would not be difficult for designers to transition to this design. This option also provides the benefit that the embedded pipe would not need to be tapered and therefore could be more easily constructed by using a standard circular HSS section. However, one major drawback to this design is that it has the potential to have fatigue problems similar to the current base plate and anchor bolt design. The welds, bolts, and plates could experience fatigue cracking after the cyclical wind stresses are imposed on the connection. Corrosion would also remain an issue with this connection. This connection does not necessarily fix the problem with fatigue associated with the current annular plate and anchor bolt design, but it does offer another alternative. Design considerations for this connection include, but are not limited to the following: • Bolt shear strength • Bolt bearing strength (on annular plates) • Flexural strength (of annular plates and bolts) • Weld strength • Axial strength (of annular plates and bolts) 89 Monopole Leveling nut Embedded steel pipe and plates Concrete foundation
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Report No. BDK75 977-04 Date: Augus
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Metric Conversion Table SYMBOL WHEN
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ALTERNATIVE SUPPORT SYSTEMS FOR CAN
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EXECUTIVE SUMMARY During the 2004 h
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CHAPTER TABLE OF CONTENTS 1 INTRODU
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Torsion Test Data .................
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LIST OF FIGURES Figure page Figure
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Figure 4-15. Arrangement of the LVD
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CHAPTER 1 INTRODUCTION This project
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CHAPTER 2 BACKGROUND The following
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information obtained in the late 19
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these problems. The concern with fa
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opposite side, see Figure 2-2 The s
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2.2.4 Helical Pipes This option wou
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2.3 Alternative Foundations from Ot
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Figure 2-10. Drilled concrete piles
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Figure 2-13. Grouted soil anchors G
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The pad and pier foundation, found
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comments and recommendations on pre
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CHAPTER 3 DESIGN IMPLICATIONS Based
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Figure 3-2. Differences between con
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2 [ ] 2 2 ( r ) + 3. 25 ( r ) − (
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eakout surface for a single plate,
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strength of a headed anchor in tens
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Figure 3-9. Schematic of anticipate
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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
Page 97 and 98: Figure 6-3. FDOT Design Standards I
Page 99 and 100: This option provides a possible alt
Page 101 and 102: 6.2.5 Cast-in-Place Solid Concrete
Page 103: This option does have some disadvan
Page 107 and 108: However, the fillet welds are susce
Page 109 and 110: APPENDIX A TEST APPARATUS DRAWINGS
Page 111 and 112: Figure A-3. Dimensioned side elevat
Page 113 and 114: Figure A-5. Dimensioned drawings of
Page 115 and 116: Figure A-7. Dimensioned plan drawin
Page 117 and 118: Figure A-9. Dimensioned drawing of
Page 119 and 120: Figure A-11. Dimensioned view of em
Page 121 and 122: STIFFENER DESIGN Calculation of Cap
Page 123 and 124: 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
Page 133 and 134: Short Pipe Design Flexural Strength
Page 135 and 136: Long Pipe Design Flexural Strength
Page 137 and 138: Superstructure Assembly Strength -
Page 139 and 140: Weld Design Tn_blowout Vweld := Tor
Page 141 and 142: Check_Bolt_Shear := "Sufficient Str
Page 143 and 144: Check Reinforcement No_Bars_Block_R
Page 145 and 146: Tie-Down Design Block Properties Wi
Page 147 and 148: Vmax Total Load that the Tie-down m
Page 149 and 150: λpf := .38⋅ λpw := 3.76⋅ E F
Page 151 and 152: Input and Properties Shaft Torsion
Page 153 and 154: 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
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REFERENCES 1. Cook, R.A., and Halco
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