Alternative Support Systems for Cantilever - National Transportation ...

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• Fatigue (of bolts, welds, and annular plates) As demonstrated by the increase in the number of design considerations, this option has more possibilities for failure. It does include welds, annular base plates, and bolts as the current base plate and anchor bolt option does. Therefore, this option does not eliminate the problems associated with the current base plate and anchor bolt design, other than removing anchor bolts as a potential failure and replacing it with a standard bolted connection. 6.2.9 Embedded Steel Pipe and Plates with Welded Sleeve Connection In this connection, a steel pipe and plate configuration would be embedded in the concrete foundation and connected to the steel monopole by a welded sleeve. The sleeve would consist of a high strength steel pipe section fillet welded to the monopole and embedded steel pipe and plates around the perimeter of the pipes. See Figure 6-10 for the connection detail. Steel pipe sleeve Figure 6-10. Embedded steel pipe and plate with welded sleeve connection One benefit of this connection is that it would be relatively easy to construct and the materials would be easy to obtain. This connection does not use bolts and thus removes bolt fatigue as a problem. The annular plate is also removed, also eliminating fatigue problems with this component of a connection. 90 Fillet weld Embedded steel pipe and plates Concrete foundation
However, the fillet welds are susceptible to fatigue cracking similar to the current base plate and anchor bolt section. Corrosion would also remain an issue because the connection is comprised totally of steel. The welded sleeve’s pipe thickness would need to be large to handle the large flexural and torsional moments presented at the connection. This connection may make it difficult to align the monopole correctly during construction. Design considerations for this connection include, but are not limited to the following: • Weld strength • Fatigue (of welds) • Flexural strength • Torsional strength • Breakout strength (of embedded section on concrete foundation) This option provides a solution to part of the fatigue problems associated with the annular plates, bolts, and welds. The welds will remain a fatigue problem. While this option may not solve all of the problems, it does provide a solution that may be relatively easy to construct. 6.2.10 Summary of Recommendations for Future Testing Future testing of alternative connections to resolve the fatigue and vibration problems exhibited in the current base plate and anchor bolt connection is highly recommended. The embedded pipe and plates configuration has been proven to be effective at transferring torsion and flexure and therefore a connection incorporating the embedded pipe and plates would be ideal. The option that may have the greatest potential that incorporates the embedded pipe and plates option is the grouted slip base connection. The benefits of this connection are that it includes the embedded pipe and plates, the design would be relatively simple, the anchor bolts are removed, and the fatigue prone welds that present a problem are eliminated. 6.3 Summary The alternative selected, the embedded pipe and plate configuration, has worked in transferring torsional and flexural load from the monopole to the foundation during experimental 91
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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
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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 and 104: This option does have some disadvan
Page 105: Figure 6-9. Embedded steel pipe and
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
Page 155 and 156: 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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