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ACKNOWLEDGMENT This work was sponsored by the American Association of State Highway and Transportation Officials (AASHTO), in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program (NCHRP), which is administered by the Transportation Research Board (TRB) of the National Academies. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, Transit Development Corporation, or AOC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.
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CONTENTS LIST OF FIGURES .......................................................................................................................... iii LIST OF TABLES ............................................................................................................................. xi ACKNOWLEDGMENTS ................................................................................................................ xii ABSTRACT ..................................................................................................................................... xiii EXECUTIVE SUMMARY ................................................................................................................ 1 CHAPTER 1: INTRODUCTION AND RESEARCH APPROACH ........................................... 3 PROBLEM STATEMENT ...................................................................................................... 3 OBJECTIVES ........................................................................................................................... 5 RESEARCH APPROACH ....................................................................................................... 5 SCOPE OF STUDY ................................................................................................................. 6 CHAPTER 2: FINDINGS .................................................................................................................. 7 REVIEW OF CONNECTION DETAILS ............................................................................... 7 IDENTIFICATION OF CRITICAL PARAMETERS .......................................................... 10 REVIEW OF CHAPTERS 10 AND 11 OF THE SPECIFICATION .................................. 13 EXPERIMENTAL AND ANALYTICAL PROTOCOLS ................................................... 18 EXPERIMENT DESIGN AND TEST MATRIX ................................................................. 23 DESIGN OF SPECIMENS .................................................................................................... 24 EXPERIMENTAL STUDIES ................................................................................................ 32 RESULTS OF EXPERIMENTAL STUDIES....................................................................... 36 PARAMETRIC STUDIES ..................................................................................................... 48 CHAPTER 3: INTERPRETATION AND APPRAISAL OF RESULTS ................................ 167 EVALUATION OF FATIGUE TEST RESULTS .............................................................. 167 FATIGUE RESISTANCE OF UNSTIFFENED POLE-TO-TRANSVERSE PLATE FILLET WELDED CONNECTIONS ................................................................................. 172 FATIGUE RESISTANCE OF UNSTIFFENED POLE-TO-TRANSVERSE PLATE GROOVE WELDED CONNECTIONS ............................................................................. 174
ii FATIGUE RESISTANCE OF STIFFENED TUBE-TO-TRANSVERSE PLATE FILLET WELDED CONNECTIONS ................................................................................................ 176 FATIGUE RESISTANCE OF HANDHOLES ................................................................... 176 FATIGUE RESISTANCE OF PASS-THROUGH MAST ARM-TO-POLE CONNECTIONS .................................................................................................................. 177 CHAPTER 4: SPECIFICATION RECOMMENDATIONS AND APPLICATION ............. 203 RECOMMENDED REVISIONS TO THE AASHTO SPECIFICATION ........................ 203 CHAPTER 5: CONCLUSIONS AND FURTHER RESEARCH ............................................. 236 CONCLUSIONS .................................................................................................................. 236 FURTHER RESEARCH ...................................................................................................... 239 REFERENCES ................................................................................................................................ 242
iii FIGURES Figure 1: Details of specimen Type I ..........................................................................................60 Figure 2: Details of specimen Type II ........................................................................................61 Figure 3: Details of specimen Type III .......................................................................................62 Figure 4: Details of specimen Type IV-A ...................................................................................63 Figure 5: Details of specimen Type IV-B ...................................................................................64 Figure 6: Details of specimen Type V ........................................................................................65 Figure 7: Details of specimen Type VI .......................................................................................66 Figure 8: Details of specimen Type VII .....................................................................................67 Figure 9: Details of specimen Type IX .......................................................................................68 Figure 10: Details of specimen Type X ......................................................................................69 Figure 11: Details of specimen Type XI .....................................................................................70 Figure 12: Details of specimen Type XII ...................................................................................71 Figure 13: Details of retrofit jacket ............................................................................................72 Figure 14: Schematic of test setups at Fritz Laboratory: (a) Plan; (b) Front Elevation; (c) Side Elevation ...............................................................................73 Figure 15: Hold down beam to reduce flexing of foundation plate .........................................74 Figure 16: Test setups in the ATLSS Center .............................................................................75 Figure 17: Strain gauge layout in specimen Type I: (a) pole base and hand hole; (b) side gusset top; (c) arm base ................................................................76 Figure 18: Strain gauge layout in specimen Type II: (a) pole base and hand hole; (b) side gusset top; (c) arm base ................................................................77 Figure 19: Strain gauge layout in specimen Type VII: (a) pole base and hand hole; (b) side gusset top; (c) arm base ................................................................78 Figure 20: Strain gauge layout in specimen Type X near pole base and hand hole ........................................................................................................................79 Figure 21: Strain measurements by 3D image correlation / photogrammetry technique ...............................................................................................................79 Figure 22: Stress profile near arm tube-to-transverse plate connection (Region 1) in specimen Type I.............................................................................80 Figure 23: Stress profile underside of bottom ring stiffener (Region 2) in specimen Type I....................................................................................................80 Figure 24: Stress profile near bottom right corner of hand-hole (Region 3) in specimen Type I....................................................................................................81
iv Figure 25: Stress profile near pole-to-base plate connection weld (Region 4) in specimen Type I ...............................................................................................81 Figure 26: Stress profile near arm tube-to-transverse plate connection (Region 1) in specimen Type II ...........................................................................82 Figure 27: Stress profile near top corner of side gusset (Region 2) in specimen Type II ..................................................................................................82 Figure 28: Stress profile near bottom right corner of hand-hole (Region 3) in specimen Type II ..................................................................................................83 Figure 29: Stress profile near pole-to-base plate connection weld (Region 4) in specimen Type II ..............................................................................................83 Figure 30: Stress profile near corner of arm tube-to-transverse plate connection in specimen Type VII .......................................................................84 Figure 31: Stress profile near middle of flat of arm tube-to-transverse plate connection in specimen Type VII .......................................................................84 Figure 32: Stress profile near corner of pole-to-base plate connection in specimen Type VII ...............................................................................................85 Figure 33: Stress profile near middle of flat of pole-to-base plate connection in specimen Type VII ...........................................................................................85 Figure 34: Stress profile near pole-to-base plate connection weld and hand hole in specimen Type X ......................................................................................86 Figure 35: Stress profile in pole wall opposite to hand hole in specimen Type X ...................................................................................................................87 Figure 36: Principal stress contour near base of pole in Specimen Type I: (a) 3D ICP measurement; (b) FEA result ................................................................87 Figure 37: Principal stress contour near hand hole in Specimen Type I: (a) 3D ICP measurement; (b) FEA result ................................................................88 Figure 38: Fatigue crack from the fillet weld termination on the tube wall in arm pole-to-transverse plate socket connection in Specimen Type I ....................................................................................................................88 Figure 39: Fatigue crack from un-fused root of hand hole frame to pole weld .....................89 Figure 40: Fracture surface of hand hole frame to pole fillet weld revealing the origin of fatigue crack from the lack of fusion and porosity at the weld root .....................................................................................................89 Figure 41: Holes drilled at the crack tip for continuing fatigue tests .....................................90 Figure 42: Fatigue cracking in arm from the toe of backing ring to tube weld (inside) ...................................................................................................................90 Figure 43: Fatigue cracking in arm from the toe of pole-to-transverse plate groove-weld ...........................................................................................................91
v Figure 44: Fatigue cracking in arm of specimen III-5 from tack weld between the backing ring and the tube wall .....................................................................91 Figure 45: Fatigue cracking in arm of specimen III-6 from tack weld between the backing ring and the tube wall .....................................................................92 Figure 46: Exposed fatigue fracture surface in the arm of specimen III-6 showing crack origin at the lack of fusion (LOF) between the tack weld and the tube wall (refer Figure 45 for view direction) ....................92 Figure 47: Fatigue cracking from gusset-to-pole fillet-weld in specimen IVB- 1..............................................................................................................................93 Figure 48: Fatigue cracking in specimen V from arm-to-clamp weld toe on the clamp ...............................................................................................................94 Figure 49: Fatigue cracking in specimen VI-2 from a weld start-stop ...................................94 Figure 50: Fatigue cracking in specimen VI-1 from weld root arrested by hole drilling in the arm sleeve .............................................................................95 Figure 51: Fatigue cracking from seam weld in the hand hole frame of specimen VII-4 .....................................................................................................95 Figure 52: Fatigue cracking from bend corner in the arm of specimen VII-7 .......................96 Figure 53: Fatigue cracking in arm of specimen VII-5, from the fillet weld toe on the tube in tube-to-transverse plate connection ...........................................96 Figure 54: Fatigue cracking from toe of pole-to-transverse plate weld in pole of specimen Type VII ...........................................................................................97 Figure 55: Fatigue crack initiation in specimen IX-2 ...............................................................97 Figure 56: Fatigue cracking in specimen IX-3 from the stool stiffener to tube weld toe at the termination of the vertical stiffener on the tube wall (with stool top plate removed) ....................................................................98 Figure 57: Fatigue cracking at pole-to-base plate fillet weld toe in high-level luminaire structure specimens ............................................................................98 Figure 58: Fatigue cracking in specimen XI-6 from termination of fillet weld toe on the tube wall of both the pole-to-transverse plate weld and the backing ring top weld.............................................................................99 Figure 59: Fatigue cracking in specimen XII-8 â A: from the stiffener to tube weld toe at the termination of the stiffener on the tube wall; and B: from the socket weld toe on the tube wall at the base ..........................99 Figure 60: Fatigue crack growth from the lack of fusion at the stiffener to tube weld root in specimen XII-6 .....................................................................100 Figure 61: Fatigue crack initiation in specimen JRXI from the root of hand hole frame to pole weld (photographed after jacket removed) ......................100 Figure 62: Geometric parameters for unstiffened fillet-welded tube-to- transverse plate connection ...............................................................................101
vi Figure 63: Geometric parameters for unstiffened groove-welded tube-to- transverse plate connection ...............................................................................101 Figure 64: Geometric parameters for stiffened tube-to-transverse plate connection ...........................................................................................................102 Figure 65: Geometric parameters for multi-sided tube .........................................................102 Figure 66: Partial factorial for unstiffened fillet- and groove-welded connections in terms of tube diameter and tube thickness ............................103 Figure 67: Partial factorial for unstiffened fillet- and groove-welded connections in terms of transverse plate thickness and bolt circle ratio ...........................................................................................................104 Figure 68: Partial factorial for stiffened fillet welded connections in terms of tube diameter and stiffener height ...................................................................104 Figure 69: Partial factorial for stiffened fillet welded connections in terms of tube thickness and stiffener thickness ..............................................................105 Figure 70: Global model of analyzed structures: (a) with unstiffened tube-to- transverse plate connection; (b) with stiffened tube-to- transverse plate connection ...............................................................................106 Figure 71: Sub-model of analyzed structures: (a) with unstiffened tube-to- transverse plate connection; (b) with stiffened tube-to- transverse plate connection ...............................................................................107 Figure 72: Effect of fastener arrangement with four fasteners .............................................107 Figure 73: Shape of fasteners, contact surfaces, and location of fixed support ...................108 Figure 74: Loading direction considered for unstiffened tube-to-transverse plate connection ..................................................................................................108 Figure 75: Loading directions considered for parametric study of stiffened tube-to-transverse plate fillet-welded connections: (a) load case 1; (b) load case 2 .................................................................................................109 Figure 76: 1st level sub-model ..................................................................................................110 Figure 77: 2nd level sub-model .................................................................................................111 Figure 78: 3rd level sub-model .................................................................................................112 Figure 79: Effect of transverse plate thickness in unstiffened round tube-to- transverse plate fillet-welded connection .........................................................113 Figure 80: Effect of bolt circle ratio in unstiffened round tube-to-transverse plate fillet-welded connection ............................................................................113 Figure 81: Effect of number of fasteners in unstiffened round tube-to- transverse plate fillet-welded connection .........................................................114 Figure 82: Effect of tube thickness in unstiffened round tube-to-transverse plate fillet-welded connection ............................................................................114
vii Figure 83: Effect of tube diameter in unstiffened round tube-to-transverse plate fillet-welded connection ............................................................................115 Figure 84: Effect of tube diameter in unstiffened round tube-to-transverse plate groove-welded connection ........................................................................115 Figure 85: Effect of tube thickness in unstiffened round tube-to-transverse plate groove-welded connection ........................................................................116 Figure 86: Effect of transverse plate opening in unstiffened round tube-to- transverse plate groove-welded connection .....................................................116 Figure 87: Effect of transverse plate thickness in unstiffened round tube-to- transverse plate groove-welded connection .....................................................117 Figure 88: Effect of bolt circle ratio in unstiffened round tube-to-transverse plate groove-welded connection ........................................................................117 Figure 89: Effect of number of fasteners in unstiffened round tube-to- transverse plate groove-welded connection .....................................................118 Figure 90: Typical contour of maximum principal stress in stiffened tube-to- transverse plate fillet-welded connections .......................................................118 Figure 91: Effect of transverse plate thicknesses in stiffened fillet-welded tube-to-transverse plate connection .................................................................119 Figure 92: Effect of thicknesses of stiffeners in stiffened fillet-welded tube-to- transverse plate connection ...............................................................................119 Figure 93: Effect of number of stiffeners in stiffened fillet-welded tube-to- transverse plate connection ...............................................................................120 Figure 94: Effect of height of stiffeners in stiffened fillet-welded tube-to- transverse plate connection ...............................................................................120 Figure 95: Effect of tube diameter in stiffened fillet-welded tube-to- transverse plate connection ...............................................................................121 Figure 96: Effect of tube thickness in stiffened fillet-welded tube-to- transverse plate connection ...............................................................................121 Figure 97: Effect of distance between stiffeners in stiffened fillet-welded tube- to-transverse plate connection ..........................................................................122 Figure 98: Effect of derived ratio of tube and stiffener thickness in stiffened fillet-welded tube-to-transverse plate connection ...........................................122 Figure 99: Effect of stiffener height on local stress ratio in stiffened fillet- welded tube-to-transverse plate connection ....................................................123 Figure 100: Effect of number of stiffeners on local stress ratio in stiffened fillet-welded tube-to-transverse plate connection ...........................................123 Figure 101: Effect of thickness of stiffener on local stress ratio in stiffened fillet-welded tube-to-transverse plate connection ...........................................124
viii Figure 102: Effect of transverse plate thickness on local stress ratio in stiffened fillet-welded tube-to-transverse plate connection ............................124 Figure 103: Effect of tube thickness on local stress ratio in stiffened fillet- welded tube-to-transverse plate connection ....................................................125 Figure 104: Effect of tube diameter on local stress ratio in stiffened fillet- welded tube-to-transverse plate connection ....................................................125 Figure 105: Effect of number of sides on local stress ratio in stiffened fillet- welded tube-to-transverse plate connection ....................................................126 Figure 106: Effect of bend radius on local stress ratio in stiffened fillet- welded tube-to-transverse plate connection ....................................................126 Figure 107: Relationship between normalized notch stress and GSCF ................................127 Figure 108: Final regression results for round tube-to-transverse plate fillet- welded connection ..............................................................................................127 Figure 109: Final regression results for round tube-to-transverse plate groove-welded connection .................................................................................128 Figure 110: Final regression results for stiffened tube-to-transverse plate fillet-welded connections at the stiffener termination on the tube wall ..............................................................................................................128 Figure 111: Variation in ratios of GSCFs in multi-sided and round tube-to- transverse plate connections with roundness for various tube diameters .............................................................................................................129 Figure 112: Variation of with roundness .............................................................................129 Figure 113: Variation of normalized ratio of notch stress and geometric stress with GSCF ................................................................................................130 Figure 114: Fatigue test results for specimen Type I..............................................................178 Figure 115: Fatigue test results for specimen Type II ............................................................178 Figure 116: Fatigue test results for specimen Type III ..........................................................179 Figure 117: Fatigue test results for unreinforced handholes .................................................179 Figure 118: Fatigue test results for specimen Type IV-A ......................................................180 Figure 119: Fatigue test results for specimen Type IV-B .......................................................180 Figure 120: Comparison of fatigue test results for specimens Type IVA and IVB ......................................................................................................................181 Figure 121: Fatigue test results for specimen Type V arm ....................................................181 Figure 122: Fatigue test results for specimen Type V pole ....................................................182 Figure 123: Fatigue test results for specimen Type VI mast arm .........................................182 Figure 124: Fatigue test results for specimen Type VI column .............................................183
ix Figure 125: Comparison of fatigue performance of groove welded tube-to- transverse plate connections .............................................................................183 Figure 126: Fatigue test results for specimen Type VII .........................................................184 Figure 127: Fatigue test results for specimen Type IX ...........................................................184 Figure 128: Fatigue test results for specimen Type X ............................................................185 Figure 129: Fatigue test results for specimen Type XI ...........................................................185 Figure 130: Fatigue test results for specimen Type XII at stiffener top ...............................186 Figure 131: Fatigue test results for specimen Type XII at pole base ....................................186 Figure 132: Fatigue test results for specimen retrofit jacket .................................................187 Figure 133: Weld profiles at the sections of crack initiation in specimens III-8 and III-9 ..............................................................................................................187 Figure 134: Fatigue crack in the arm of specimen III-9; the broken line indicates the location of the section in Figure 133 ..........................................188 Figure 135: Contour of principal stress in specimen Type V at arm -clamp connection with pole ..........................................................................................189 Figure 136: Stress at arm-to-clamp connection in specimen Type V ....................................190 Figure 137: Close-up of weld toe at arm-to-clamp connection in specimen Type V: (a) weld toe on the arm; and (b) cracked weld toe on the clamp .............................................................................................................190 Figure 138: Contour of principal stress in specimen Type VI at arm sleeve to pole connection ...................................................................................................191 Figure 139: Weld profile: (a) column side weld, (b) sleeve side weld ....................................191 Figure 140: Comparing FEA stresses and strain gauge measured stresses .........................192 Figure 141: Fatigue resistance of fillet-welded tube-to-transverse plate connections â finite life ....................................................................................192 Figure 142: Fatigue resistance of fillet-welded tube-to-transverse plate connections â infinite life .................................................................................193 Figure 143: Comparison of fatigue resistance in round and multi-sided sections ................................................................................................................193 Figure 144: Comparison of geometric stress distribution in round and multi- sided sections â around perimeter ..................................................................194 Figure 145: Comparison of geometric stress distribution in round and multi- sided sections â longitudinal direction ...........................................................195 Figure 146: Variation in notch stress in multi-sided sections ................................................195 Figure 147: Fatigue resistance of full penetration groove-welded tube-to- transverse plate connections â finite life ........................................................196
x Figure 148: Fatigue resistance of full penetration groove-welded tube-to- transverse plate connections â infinite life .....................................................196 Figure 149: Effect of opening in transverse plate on fatigue resistance of full penetration groove-welded tube-to-transverse plate connections..........................................................................................................197 Figure 150: Comparison of fillet- and groove-welded tube-to transverse plate connections with similar GSCF ........................................................................197 Figure 151: Fatigue resistance of stiffener termination in stiffened fillet- welded connections.............................................................................................198 Figure 152: Quality of backing ring weld toe and fatigue cracking ......................................198 Figure 153: Lack of fusion at the backing ring-to-tube weld .................................................199 Figure 154: Polished and etched section showing lack of fusion at the backing ring-to-tube weld (Figure 153) ..........................................................................199 Figure 155: Fatigue resistance of stiffener termination in stiffened fillet- welded connections.............................................................................................200 Figure 156: Fatigue resistance of reinforced handholes against cracking from handhole frame-to-pole weld root ....................................................................200 Figure 157: Fatigue resistance of reinforced handholes against cracking from handhole frame-to-pole weld toe ......................................................................201 Figure 158: Fatigue resistance of unreinforced handholes ....................................................201 Figure 159: Fatigue resistance of mast-arm-to-pole pass-through connections ...................202
xi TABLES Table 1: Details Identified for Investigation ............................................................................131 Table 2: Test Matrix ..................................................................................................................134 Table 3: Distribution of Round Specimens and Details .........................................................135 Table 4: Distribution of Multi-sided Specimens and Details .................................................136 Table 5: Summary of Fatigue Test Results..............................................................................137 Table 6: Nomenclature of Geometric Parameters ..................................................................164 Table 7: Range of Parametric Study Variables for Fillet-welded Tube-to- Transverse Plate Connections ...........................................................................164 Table 8: Range of Parametric Study Variables for Groove-welded Tube-to- Transverse Plate Connections ...........................................................................165 Table 9: Range of Parametric Study Variables for Stiffened Tube-to- Transverse Plate Connections ...........................................................................166 Table 10: Range of Parametric Study Variables for Multi-sided Sections ..........................166
xii ACKNOWLEDGMENTS The research reported herein was performed under NCHRP Project 10-70 by the ATLSS Center at Lehigh University. Dr. Richard Sause, P.E., Joseph T. Stuart Professor of Structural Engineering and Director of the ATLSS Center at Lehigh University, and Dr. Sougata Roy, Senior Research Scientist at the ATLSS Center, Lehigh University were the principal investigators. The other authors of this report are Mr. Yeun Chul Park, Research Assistant and Ph.D. Candidate at Lehigh University, Dr. Eric J. Kaufmann, Senior Research Scientist at the ATLSS Center, and Dr. John W. Fisher, P.E., Professor Emeritus of Civil and Environmental Engineering at Lehigh University. The work was conducted under the primary guidance and supervision of Dr. Roy. The authors acknowledge the valuable contributions of other members of the research team during various phases of the work: Mr. Reilly W. Thompson, and Mr. Nirab K. Manandhar, Research Assistants and M.S. Candidates at Lehigh University; and Dr. Ben T. Yen, Professor Emeritus of Civil and Environmental Engineering at Lehigh University. The authors also thank Professor Karl H. Frank of the University of Texas at Austin for sharing interim research results from Transportation Pooled Fund Study TPF-5(116). Special thanks are due to the entire staff of the ATLSS Center for providing support during the execution of this project. Fabricators of test specimens: Valmont Industries Inc. of Nebraska, Millerbernd Manufacturing of Minnesota, and Union Metal of Ohio are gratefully acknowledged for their generous support. Finally, the authors would like to acknowledge the patience and guidance of the NCHRP project panel members. Several figures developed under NCHRP Project 10-70 and presented in this report have been published previously: ï· Figure 56. Fatigue cracking in specimen IX-3 from the stool stiffener to tube weld toe at the termination of the vertical stiffener on the tube wall (with stool top plate removed). (From Roy, S., Y.C. Park, R. Sause, and J. W. Fisher. Fatigue Resistance of Pole-to-Base Plate Connections in High Level Lighting Structures. In Proceedings ASCE Structures Congress 2010, Figure 7.) ï· Figure 58. Fatigue cracking in specimen XI-6 from termination of fillet weld toe on the tube wall of both the pole-to-transverse plate weld and the backing ring top weld (From Roy, S., Y.-Chul Park, R. Sause, and J. Fisher. Fatigue Performance of Groove-Welded Tube-to-End-Plate Connections in Highway Sign, Luminaire, and Traffic Signal Structures. In Transportation Research Record: Journal of the Transportation Research Board, No. 2152, Figure 5.) ï· Figure 59. Fatigue cracking in specimen XII-8 â A: from the stiffener to tube weld toe at the termination of the stiffener on the tube wall; and B: from the socket weld toe on the tube wall at the base. (From Roy, S., Y.C. Park, R. Sause, and J. W. Fisher. Fatigue Resistance of Pole-to-Base Plate Connections
