Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections (2022) / Chapter Skim
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56 Experimental Testing 3.1 Introduction Experimental testing was performed on the UHPC longitudinal joint and the continuity connection. This was to verify analytical results and determine differences that cannot always be modeled.
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Experimental Testing 57 Figure 3.1. Top view of girder layout.
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58 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.4. Surface temperature.
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Experimental Testing 59 Figure 3.6. Internal sensor locations.
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60 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.8. Temperature gradient, 2:21 p.m.
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Experimental Testing 61 of the unrestrained joints due to the thermal cycle. Figure 3.11 shows the location of the vibrating wire gauges used to measure the joint displacements.
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62 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.12 shows the results of the joint gauges during a thermal cycle run on November 20. As shown by Figure 3.12, the top of the joint contracted more than the bottom.
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Experimental Testing 63 the United States. The research team (RT)
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64 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections e UHPC was transferred from the mixer in buckets into chimneys (orange and white buckets in Figure 3.13) at approximately the third points along the joint.
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Experimental Testing 65 was used to ensure the UHPC did not leak out of the joint and gave an approximately ⅛-in. height above the joint.
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66 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.15. Temperature gradient during UHPC placement, 12/21/2020.
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Experimental Testing 67 Figure 3.17. Strains across joint 12, 12/21/2020.
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68 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.19. Vibrating wire gauges across the joints.
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Experimental Testing 69 The temperature gradient was determined from the average temperatures of the gauges near the top surface of the girder (gauges 5 and 6 in Figure 3.6) compared to the internal gauge near the bottom surface of the girder (gauge 1 in Figure 3.6)
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70 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.22. Girder reactions, 12/22/2020.
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Experimental Testing 71 Figure 3.24. Temperature gradient 2 days after UHPC placement, 12/23/2020.
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72 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections 3.2.1.6 Thermal Behavior 5 Days after UHPC Placement and Formwork Removal On December 26, 2020, girder 2 had the largest thermal gradient and girders 1 and 3 had similar lower gradients, as shown in Figure 3.27 for this thermal cycle. The camber of girder 2 remained the largest, while girder 1's camber was slightly more than that of girder 3, as shown in Figure 3.28.
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Experimental Testing 73 Figure 3.27. Temperature gradient, 12/26/2020.
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74 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.29. Girder reactions, 12/26/2020.
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Experimental Testing 75 Figure 3.31. Temperature gradient, 1/25/2021.
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76 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.33. Girder reactions, 1/25/2021.
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Experimental Testing 77 3.2.1.8 Thermal Behavior over a Month after UHPC Placement and Formwork Removal The thermal cycle on January 27, 2021, was very similar to that on January 25. However, unlike December 26, 2020, and January 25, 2021, girders 1 and 3 had larger thermal gradients than girder 2, as shown in Figure 3.36.
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78 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.36. Temperature gradient, 1/27/2021.
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Experimental Testing 79 with the strain at location J12-2 again increasing positively with the increase in temperature and then dropped off during cooling. 3.2.1.10 Cyclic Live Loading After the thermal cycles were completed, cyclic live loading was applied to the system from a load of 0 kips to 70 kips for 100,000 cycles.
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80 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections (a) End view with midspan loading also shown: test 1 with girders 1–3 (b)
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Experimental Testing 81 Figure 3.41. Load frame with insulated box.
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82 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.43. Camber, 4/26/2021.
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Experimental Testing 83 Figure 3.45. Joint 12 rebar strains, 4/26/2021.
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84 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections not indicate any cracking. However, the RT had concerns about cracking based on some of the instrument strain reading jumps.
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Experimental Testing 85 Interface crack Figure 3.49. Interface leakage.
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86 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Overlapping UHPC UHPC crack Figure 3.51. Joint 2-3 UHPC cracking.
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Experimental Testing 87 (a)
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88 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.53. Differential camber.
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Experimental Testing 89 Figure 3.56. Removal of differential camber.
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90 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections The load used to remove the differential camber was then released gradually in steps as shown by the girder reactions in Figure 3.58. The girder cambers are provided in Figure 3.59: girder 4 had the largest midspan camber of slightly more than 0.20 in.
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Experimental Testing 91 Figure 3.58. Girder reactions from load release.
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92 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections (a)
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Figure 3.61. Camber from static loading, 6/16/2021.
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94 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Figure 3.63. Reactions from static loading, 6/16/2021.
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Experimental Testing 95 Figure 3.65. Core slice with crack.
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96 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections 3.3 Continuity Joint Testing The continuity joint test consisted of two 20-ft. PCEF 39-in.-deep girders placed end to end.
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Experimental Testing 97 Figure 3.68. Continuity joint reinforcement.
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98 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections Embedded Strain Gauge Figure 3.70. Continuity joint top reinforcement instrumentation.
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Experimental Testing 99 Age (days) Average Compressive Strength (psi)
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100 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections shown in Figure 3.74, were very small. As expected, gauge 1 near the bottom of the connection experienced tension, while the gauges in the flanges (gauges 3–5)
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Experimental Testing 101 Gauge 1 Gauge 2 Gauge 3 Gauge 4 Gauge 5 Figure 3.74. Continuity joint strains from positive moment.
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Figure 3.77. Strains in reinforcement from west girder.
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Experimental Testing 103 increase and indicated yielding. The load of 98 kips corresponds to a total moment of 1,357 kip-ft., including the self-weight.
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104 Design and Construction of Deck Bulb Tee Girder Bridges with UHPC Connections in the east end of the joints. The UHPC was placed in the east ends last and seemed to have slower flow.
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