Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Seismic performance of accelerated bridge construction (ABC) precast bulb-tee girder-to-bent cap connection Zhao Cheng Iowa State University Follow this and additional works at:https://lib.dr.iastate.edu/etd Part of theCivil Engineering Commons, and theStructural Engineering Commons Recommended Citation Cheng, Zhao, "Seismic performance of accelerated bridge construction (ABC) precast bulb-tee girder-to-bent cap connection" (2015).Graduate Theses and Dissertations. 14670. https://lib.dr.iastate.edu/etd/14670 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please [email protected]. Seismic performance of accelerated bridge construction (ABC) precast bulb-tee girder-to-bent cap connection by Zhao Cheng A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Civil Engineering (Structural Engineering) Program of Study Committee: Sri Sritharan, Major Professor Jon Matthew Rouse Hyung Seok Jeong Iowa State University Ames, Iowa 2015 Copyright © Zhao Cheng, 2015. All rights reserved. ii TABLE OF CONTENTS TABLE OF FIGURES ........................................................................................................ v TABLE OF TABLES ........................................................................................................ xi ACKNOWLEDGEMENTS .............................................................................................. xii ABSTRACT ..................................................................................................................... xiii CHAPTER 1 INTRODUCTION ..................................................................................... 1 1.1 Background ............................................................................................................ 1 1.2 Accelerated Bridge Construction ........................................................................... 3 1.3 Seismic Design Philosophy ................................................................................... 5 1.4 ABC Connections for Seismic Region .................................................................. 6 1.5 Research Objectives ............................................................................................... 9 1.6 Thesis Layout ....................................................................................................... 10 CHAPTER 2 LITERATURE REVIEW ........................................................................ 11 2.1 Causes of Moment at Girder-to-Bent Cap Connection ........................................ 11 2.1.1 Gravity loads ................................................................................................ 12 2.1.2 Time-dependent effects and temperature gradient........................................ 13 2.1.3 Seismic loads ................................................................................................ 15 2.2 Moment Resisting Connection for Precast Girders ............................................. 18 2.2.1 Continuity connections designed for restraint moments............................... 19 2.2.2 Continuity connection designed for seismic loads ....................................... 24 2.2.3 Concerns and issues related to moment resisting connections ..................... 33 2.3 Expected Connection Mechanisms ...................................................................... 35 2.3.1 Bond-slip behavior ........................................................................................ 35 2.3.2 Shear friction behavior.................................................................................. 43 2.4 Structural Model and Experimental Techniques ................................................. 46 2.4.1 Similitude theory .......................................................................................... 47 2.4.2 Experimental techniques ............................................................................... 48 CHAPTER 3 DESIGN OF TEST UNIT ....................................................................... 50 3.1 Prototype Bridge .................................................................................................. 50 3.1.1 Column design .............................................................................................. 51 iii 3.1.2 Girder and deck design ................................................................................. 51 3.1.3 Bent cap design ............................................................................................. 52 3.1.4 Girder-to-bent cap connection design ........................................................... 52 3.2 Test Unit Design ................................................................................................... 58 3.2.1 Girder design ................................................................................................ 59 3.2.2 Bent cap design ............................................................................................. 60 3.2.3 Connection design ........................................................................................ 61 3.2.4 Column and footing design .......................................................................... 62 CHAPTER 4 EXPERIMENTAL WORK ..................................................................... 64 4.1 Test Unit Construction ......................................................................................... 64 4.1.1 Construction sequence .................................................................................. 64 4.1.2 Construction challenges ................................................................................ 67 4.2 Instrumentation .................................................................................................... 68 4.2.1 Internal instrumentation ................................................................................ 68 4.2.2 External instrumentation ............................................................................... 78 4.3 Load Protocol ....................................................................................................... 82 4.3.1 Gravity load .................................................................................................. 83 4.3.2 Horizontal seismic load ................................................................................ 84 4.3.3 Vertical acceleration effects.......................................................................... 85 4.3.4 Load combination of the load protocol ......................................................... 85 CHAPTER 5 TEST RESULTS ..................................................................................... 89 5.1 Overall Performance ............................................................................................ 89 5.1.1 The ESMS connection .................................................................................. 89 5.1.2 The ESLS connection ................................................................................... 95 5.2 Girder-to-Cap Interface Performance .................................................................. 99 5.3 Unstressed Strands and Dowel Bars Performance ............................................. 101 5.4 Failure Mechanism ............................................................................................ 104 5.4.1 Negative moment behavior ......................................................................... 104 5.4.2 Positive moment behavior .......................................................................... 109 CHAPTER 6 DESIGN METHOLODIES ................................................................... 113 6.1 Negative Moment .............................................................................................. 113 6.2 Positive Moment ................................................................................................ 119 iv 6.2.1 Shear friction behavior................................................................................ 120 6.2.2 Extended girder strands .............................................................................. 126 CHAPTER 7 CONCLUSIONS AND RECOMMENDATIONS ................................ 132 7.1 Overview ............................................................................................................ 132 7.2 Summary of Experimental Test Results ............................................................ 133 7.2.1 ESMS connection ....................................................................................... 133 7.2.2 ESLS connection ........................................................................................ 134 7.3 Conclusions ........................................................................................................ 135 7.4 Design Recommendations ................................................................................. 136 7.5 Future Research ................................................................................................. 138 REFERENCES ............................................................................................................... 139 APPENDX A TEST UNIT DRAWINGS .................................................................. 145 APPENDX B LOADING PROTOCOL .................................................................... 150 v TABLE OF FIGURES Figure 1-1 ABC with Prefabricated Components ................................................................4 Figure 1-2 Illustrative Example for Design Moment Demand ............................................6 Figure 1-3 Examples of Moment Resisting Connections between Column and Superstructure/Foundation for ABC Application ............................................7 Figure 1-4 Typical Integral Girder to Bent Cap Connection ...............................................8 Figure 1-5 A Schematic View of the Extend Strand with a Mechanical Splice (ESMS) Connection .......................................................................................................9 Figure 1-6 A Schematic View of the Extend Strand with a Lap Splice (ESLS) Connection .....................................................................................................10 Figure 2-1 Construction Sequence for Superstructure with Permanent Supports .............12 Figure 2-2 Construction Sequence for Superstructure with Temporary Supports .............13 Figure 2-3 Cantilever Column vs. Framed Column...........................................................17 Figure 2-4 Equilibrium of Forces on Bent Cap under Column Overstrength....................17 Figure 2-5 Vertical Acceleration Effects on a Continuous Superstructure........................18 Figure 2-6 PCA Method Connection .................................................................................20 Figure 2-7 Details of the Connections ...............................................................................23 Figure 2-8 Bent Bar Specimen with Partial Diaphragm ....................................................24 Figure 2-9 Full-size Specimen with Bent Strand ...............................................................24 Figure 2-10 Energy-dissipating (ED) vs. Capacity-protected (CP) Connections ..............25 Figure 2-11 Prototype Girder to Bent Cap Connection Details .........................................27 Figure 2-12 Test Unit with Five Girders on Each Side .....................................................29 Figure 2-13 As-built Connection and Improved Connection Details ................................29 vi Figure 2-14 Schematics View of Precast Girder to Bent Cap Connection Details ............32 Figure 2-15 Congestion within Connection Region due to the Use of Bent Bars .............34 Figure 2-16 Bond Force Transfer Mechanisms .................................................................36 Figure 2-17 Cracks between Bars and Concrete due to local Concrete Crushing .............36 Figure 2-18 Bond-slip Model Proposed by Eligehausen et al. ..........................................37 Figure 2-19 Bond-slip Model Proposed by Zhao and Sritharan ........................................38 Figure 2-20 Bar Stress vs. Load-end Slip Relationship .....................................................39 Figure 2-21 Slip as a function of loaded end steel stress for the four embedment lengths of the bent series ............................................................................................41 Figure 2-22 Measured and Analytical Strain Distribution Comparisons ...........................42 Figure 2-23 Shear Friction Mechanisms ............................................................................44 Figure 3-1 Prototype Bridge for Third Test Unit ...............................................................51 Figure 3-2 ESMS Connection Schematic ..........................................................................57 Figure 3-3 ESLS Connection Schematic ...........................................................................58 Figure 3-4 Expected Anchorage Mechanism for Strands in the ESLS Connection ..........58 Figure 3-5 Region of Highest Moment during Seismic Activities ....................................58 Figure 3-6 Cross-section of Prototype Girder (left) and Test Unit Girder ........................60 Figure 3-7 Addition of “U”-shaped confinement steel ......................................................62 Figure 3-8 Post-tensioning Bars Schematic .......................................................................63 Figure 4-1 Place the Girder on Temporary Falsework ......................................................64 Figure 4-2 Dowel Bars Inserted through the Web of Girder .............................................65 Figure 4-3 Extended Girder Strands in the ESMS and ESLS Connections .......................66 Figure 4-4 Reinforcement Cage for Bent Cap and Deck Reinforcing Steel ......................66 vii Figure 4-5 Test Unit with the ESMS and ESLS Connections ...........................................66 Figure 4-6 Unraveling of Unstressed Strand .....................................................................67 Figure 4-7 Strain Gauge Location for the Bent Cap Longitudinal Reinforcing Bars ........69 Figure 4-8 Strain Gauge Location for Cap Stirrups ...........................................................70 Figure 4-9 Location of Strain Gauges in a Prestressed Strand of Each Bulb-tee Girder ...71 Figure 4-10 Location of Strain Gauge Mounted to the Dowel Bars ..................................73 Figure 4-11 Location of Strain Gages on the Dowel Confinement Reinforcing Bars .......74 Figure 4-12 Location of Strain Gauges on the Extended Strands in the ESMS Connection .....................................................................................................76 Figure 4-13 Location of Strain Gauges on the Strands in the ESLS connection ...............76 Figure 4-14 Placement of Strain Gauge on Unraveled Portion of a Strand in the ESMS Connection .....................................................................................................77 Figure 4-15 Location of Strain Gauges on the Deck Reinforcement .................................78 Figure 4-16 Location of External Sensors for Bent cap ....................................................79 Figure 4-17 Location of External Sensors for Precast Girder ............................................79 Figure 4-18 Location of LVDTs on Deck..........................................................................80 Figure 4-19 Location of LVDT on Girder to cap interface ...............................................81 Figure 4-20 Optotrak System Marker Layout ....................................................................82 Figure 4-21 Test Unit Setup ...............................................................................................82 Figure 4-22 Construction Sequence ...................................................................................84 Figure 4-23 Moment at Girder to Bent Cap Resulting from Horizontal Seismic Exaction .........................................................................................................85 Figure 4-24 Difference in Gravity Moment for Actual Case and Load Protocol ..............86 viii Figure 4-25 (a) Moment and (b) Shear applied at Test Unit and Prototype Loads ...........87 Figure 4-26 Loading Sequence for Test Unit ....................................................................88 Figure 5-1 the Measured Moment Resistance versus Black Actuator Displacement ........91 Figure 5-2 Flexural Cracks on Deck of the ESMS Connection .........................................92 Figure 5-3 (a) Visual Separation of Girder Cover Concrete with Girder Strands; (b) Spalling of Concrete at Bent Cap behind Girder; (c) the Void formed between the girder and Bent Cap ...................................................................93 Figure 5-4 (a) Separation between Girder End and Bent Cap; (b) Penetration Cracks on Diaphragm; (c) Diaphragm Region where the Spalling of Concrete Was Observed ................................................................................................94 Figure 5-5 the Measured Moment Resistance versus the Black Actuator Displacement ..96 Figure 5-6 Cracks on Deck of the ESLS Connection ........................................................97 Figure 5-7 (a) Spalling of Cover Concrete at Girder End; (b) Spalling of Concrete at Bent Cap behind Girder; (c) the Void Formed Between the Girder and Bent Cap ........................................................................................................98 Figure 5-8 (a) Penetration Cracks on the Diaphragm after Overloading Process; (b) Concrete Next to Girder Spalled off; (c) Fracture of the Strands within the ESLS Connection ....................................................................................99 Figure 5-9 Illustration of Girder to Cap Interface Performance ......................................101 Figure 5-10 Strain Distribution along Strand in the ESMS Connection ..........................102 Figure 5-11 Strain Distribution along Strand in the ESLS Connection ...........................103 Figure 5-12 Relative Distance between the Bottom of Girder and the Bent Cap ............106 ix Figure 5-13 Negative Moment versus Rotation and Negative Moment versus Deck Reinforcement Strain for the ESMS Connection ........................................106 Figure 5-14 Negative Moment versus Rotation and Negative Moment versus Relative Distance of Girder End and Bent Cap for the ESMS Connection ...............107 Figure 5-15 Negative Moment versus Rotation and Negative Moment versus Relative Distance of Girder End to the Bent Cap for the ESLS Connection .............108 Figure 5-16 Estimating the Contribution of the Positive Moment Resistance in the ESMS Connection .......................................................................................110 Figure 5-17 Estimating the Contribution of the Positive Moment Resistance in the ESMS Connection .......................................................................................111 Figure 6-1 Section of the Precast Bulb-Tee Girder to Bent Cap Connection in Negative Moment Direction .......................................................................................114 Figure 6-2 Results of Sectional Analysis .........................................................................115 Figure 6-3 Experimental Measured Relative Distance between Girder End and the Bend Cap .....................................................................................................116 Figure 6-4 Assumed Rotation at Girder to Bent Cap Connection under Negative Moment ........................................................................................................117 Figure 6-5 Comparison between the Predicted Behavior and the Experimental Behavior in Negative Moment Direction ....................................................119 Figure 6-6 Relative Distance at the Bottom of Girder End under Negative Moment for Full-Scale 7 ft – 5/8 in. Depth Bulb-Tee Girders ........................................119 Figure 6-7 An Illustration Showing Pull out of an Embedded girder into the Diaphragm .....................................................................................................................120