Alternative Support Systems for Cantilever - National Transportation ...

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• Torsional strength • Flexural strength 6.2.6 Embedded Concrete Pipe with Bolts Option with Grouted Splice to Concrete Monopole In this option, a prestressed concrete pipe with bolted plates would be embedded into a concrete foundation. The bolts and plates would resist torsion by bearing on the surrounding concrete foundation. The splice would be similar to that presented in FDOT Project BC354-80 Final Report, Volume 2 (19). See Figure 6-7 for the setup of this connection. The splice connection would be a steel HSS pipe with welded rebar hoops placed in the hollow core of the prestressed spun concrete pipe and then pressure grouted into place. Figure 6-7. Embedded concrete pipe with bolts option with grouted splice to concrete monopole This option has several advantages over the current annular plate and anchor bolt connection. The primary advantage is that the connection does not use annular plates or anchor bolts and will eliminate the fatigue problems associated with the current connection option. Another advantage is that since the steel portion of the connection is grouted in the core of the spun concrete poles, the steel will not suffer as much corrosion unless one of the grout inlet holes is compromised. Tapered concrete monopole Grout Grout seal Steel plate 86 Steel HSS pipe with welded rebar hoops Embedded concrete pipe with bolts Concrete foundation
This option does have some disadvantages as well. The construction will be more tedious and time consuming than the current connection option. This connection can be more costly than the current connection option because of the increase in number of elements as well as the cost of each element. The inclusion of grout adds an additional complication for design and construction error. The viability of a concrete monopole for cantilever use is also questionable. The horizontal member that needs to be attached for sign/signal purposes may be too large to attach to the concrete monopole. This connection may be more difficult to monitor and repair than a visible connection. following: 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 6.2.7 Embedded Steel Pipe and Hoops with Grouted Slip Base Connection This option entails using a steel pipe and hoops embedded into the foundation and stubbing out from the foundation. The steel pipe and hoops would then be covered by a concrete monopole and pressure grouted into place. See Figure 6-8 for this connection configuration. The primary benefit of this connection is that it removes the fatigue-prone elements of the current anchor bolt and annular base plate connection. It offers good torsional and flexural resistance with the embedded pipe and hoop section. The pipe and hoop section may be expensive to fabricate. The pressure grouting has the potential to be a problem during construction as it has been a problem in the past. As mentioned earlier, the concrete monopole 87
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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
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
Page 97 and 98: Figure 6-3. FDOT Design Standards I
Page 99 and 100: This option provides a possible alt
Page 101: 6.2.5 Cast-in-Place Solid Concrete
Page 105 and 106: Figure 6-9. Embedded steel pipe and
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
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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
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REFERENCES 1. Cook, R.A., and Halco
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