Alternative Support Systems for Cantilever - National Transportation ...

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The accurate testing predictions using the modified code equations were the basis for the development of the design guidelines. The design guidelines account for the design of the base connection as well as the foundation, including the pipe and plates section and concrete pedestal and reinforcement. Implementation of the recommended alternative and design guidelines for foundations of cantilever signal/sign structures should eliminate any concrete breakout problems associated with the anchor bolts. The recommended alternative connections are highly recommended for further investigation. The combination of the embedded pipe and plate section and a selected alternative connection would significantly reduce the number of failures of cantilever signal/sign structures. viii
CHAPTER TABLE OF CONTENTS 1 INTRODUCTION ....................................................................................................................1 2 BACKGROUND ......................................................................................................................3 ix page 2.1 Current Anchor Bolt Foundation System ...........................................................................3 2.2 Alternative Foundation Systems .........................................................................................7 2.2.1 Steel Pipes with Plates Welded at Four Locations ...................................................7 2.2.2 Geometric Hollow Section .......................................................................................9 2.2.3 Pipe with Welded Studs ..........................................................................................10 2.2.4 Helical Pipes ...........................................................................................................11 2.2.5 Embedded Geometric Tapered Section ..................................................................12 2.3 Alternative Foundations from Other Industries ................................................................13 2.3.1 Transmission Line Foundations .............................................................................13 2.3.2 Wind Turbine Foundations .....................................................................................18 2.3.3 Cellular Tower Foundations ...................................................................................19 2.3.4 Advertising Monopole Foundations .......................................................................20 2.4 Selection ...........................................................................................................................21 3 DESIGN IMPLICATIONS ....................................................................................................23 3.1 Design for Torsion ............................................................................................................23 3.1.1 Equivalent Concrete Breakout Strength in Shear ...................................................23 3.1.2 Equivalent Side-Face Blowout Strength ................................................................30 3.2 Design for Flexure ............................................................................................................33 3.2.1 Equivalent Concrete Breakout Strength in Shear ...................................................33 3.2.2 Equivalent Side-Face Blowout Strength ................................................................37 3.3 Design Implications Summary .........................................................................................39 4 DEVELOPMENT OF EXPERIMENTAL PROGRAM ........................................................40 4.1 Description of Test Apparatus ..........................................................................................41 4.2 Embedded Pipe and Plate Design .....................................................................................47 4.2.1 Concrete Breakout and Bearing Strength ...............................................................47 4.2.2 Welded Stiffener Plates Design ..............................................................................48 4.2.3 Annular Flexural Plate Design ...............................................................................50 4.2.4 Annular Base Plate Design .....................................................................................51 4.2.5 Pipe Design .............................................................................................................51 4.3 Concrete Shaft Design ......................................................................................................51 4.3.1 Concrete Shaft Diameter Design ............................................................................52 4.3.2 Torsion Design .......................................................................................................53 4.3.3 Longitudinal and Transverse Reinforcement .........................................................54 4.3.4 Flexure Design ........................................................................................................54
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: EXECUTIVE SUMMARY During the 2004 h
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 and 40: CHAPTER 3 DESIGN IMPLICATIONS Based
Page 41 and 42: Figure 3-2. Differences between con
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.
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Figure 4-8. Isometric view of embed
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Flexural plate breakout area Torsio
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4.2.4 Annular Base Plate Design The
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torsional strength of the lever arm
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4.4 Concrete Block and Tie-Down Des
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Figure 4-13. Arrangement of the LVD
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4.7 Summary of Torsion and Flexure
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foundation displayed the predicted
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Figure 5-5. Specimen at failure 5.1
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Figure 5-7. Torsional moment and ro
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torsional 45 degree crack formation
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Figure 5-11. Widening of concrete b
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Failure cracks widen Bond loosens F
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Rear of shaft Figure 5-14. Load and
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testing, signifying that the predic
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provided in NCHRP Report 412 were i
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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
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STIFFENER DESIGN Calculation of Cap
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L breakout Concrete Breakout Equiva
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Abrg L⋅b 7 in 2 := = .5 Nsb 200
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β 1 f c Calculations Using ACI Str
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Determine Flexural Capacity of Roun
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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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