Assessment of the Bill Emerson Memorial Bridge - FTP Directory ...

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1.00.986 0.952 0.9570.888 0.892 0.9050.8MAC0.60.40.20.01 2 3 4 5 6 7 8ModeFigure 5.46 Mode assurance criterion (MAC) values5.5. RemarksThe eigensolution, sensitivity, and validation of the Bill Emerson Memorial Cable-stayedBridge model have been performed in great details. Based on extensive numerical results,the following observations can be made:1. The 3-D response and behavior of the cable-stayed bridge are evident. Most of thevibration modes are coupled with others. The dynamic characteristics (frequencyand mode shapes) of the bridge indicate that the cable-stayed structure is mostflexible in vertical direction and least flexible in longitudinal direction.2. The 31 significant modes of vibration up to 14.09 Hz include more than 70%mass participation in translational and rotational motions along any of threedirections. The fundamental frequency is 0.339 Hz, corresponding to verticalvibration of the main bridge. Cables begin to vibrate severely at a naturalfrequency of 0.842 Hz or higher. The Illinois approach spans experiencesignificant vibration at approximately 3.187 Hz. The approach spans is muchstiffer than the cable-stayed span. Their interaction during earthquakes is weak.3. The 3-D FE model of the cable-stayed bridge is robust and reliable. Based onsensitivity analysis, the key parameters affecting the modal properties of thebridge are the mass density of concrete and boundary conditions. The massdensity of concrete, specified in bridge drawings, appear underestimated by 6.7%.They need to be increased in order to match the natural frequencies of the 3-Dmodel with their respective measured data. Except for expansion conditions, theuse of other boundary conditions at bases of all piers changes the naturalfrequency of the main bridge by less than 5%.4. The computed natural frequencies of the 3-D FE model agree well with thosefrom field measured data. For mode shapes, however, slight differences existbetween the computed and the measured values. One of the reasons for these76
differences is that the exact locations of all accelerometers deployed on the bridgeare unknown. Nevertheless, the mode assurance criterion index between acomputed mode shape and its corresponding measured one is above 0.888 for thefirst eight modes. This indicates that the 3-D FE model is reasonable forengineering applications.77
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Organizational Results Research Rep
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TECHNICAL REPORT DOCUMENTATION PAGE
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Executive SummaryOpen to traffic on
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8. All cables behave elastically un
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Table of ContentsExecutive summary.
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List of Figure CaptionsFigure 1.1 A
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Figure 5.30 29 th mode shape (1.032
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1. Introduction1.1. GeneralCable-st
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Figure 1.1Artist rendering of the B
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Expansionand lateralearthquakerestr
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3. Evaluate the model by conducting
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2. Automatic Retrieval of Peak Acce
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2.2.3. Map/Find stationsClicking th
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2.2.5. Displaying seismogramsTo dis
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Figure 2.8Directory chooser2.2.6. S
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3.2. Seismic instrumentation networ
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The main bridge from Bent 1 to Pier
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(a) South side of deck at support o
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(a) North side of deck at middle of
Page 39 and 40: The seismic responses at the top (T
Page 41 and 42: Polyreference Complex Exponential (
Page 43 and 44: are evaluated and presented in Figu
Page 45 and 46: 0.353.50.330.252.5Amplitude0.20.15A
Page 47 and 48: 1 x 10-4 Frequency(Hz)Amplitude0.90
Page 49 and 50: Amplitude0.20.180.160.140.120.10.08
Page 51 and 52: Amplitude0.20.180.160.140.120.10.08
Page 53 and 54: 1.20.80.400 100 200 300 400 500 600
Page 55 and 56: 4. Finite Element Modeling of Bill
Page 57 and 58: Since the cable stays are connected
Page 59 and 60: Table 4.3Initial property of cables
Page 61 and 62: Table 4.4Spring and damping coeffic
Page 63 and 64: (a) View of the entire bridge(b) Vi
Page 65 and 66: 4.6. RemarksA detailed 3-D FE model
Page 67 and 68: knω = (5.4)nm nSimilarly, when dam
Page 69 and 70: mainly corresponds to the vertical
Page 71 and 72: thFigure 5.10 9 mode shape (0.740Hz
Page 73 and 74: thFigure 5.19 18 mode shape (0.947H
Page 75 and 76: Figure 5.27 26 th mode shape (0.977
Page 77 and 78: When the bridge deck moves up and d
Page 79 and 80: 1.1Frequency (Hz)0.90.70.5BC Case 1
Page 81 and 82: 1.1Frequency(Hz)0.90.70.5Plus 0Plus
Page 83 and 84: no difference among the three cases
Page 85 and 86: The FE model of the bridge was vali
Page 87 and 88: 10.6TestFE model0.2-0.20 100 200 30
Page 89: 1.20.80.40-0.4TestFE model0 100 200
Page 93 and 94: (a) Vertical acceleration time hist
Page 95 and 96: The FE model of the cable-stayed br
Page 97 and 98: Displacement (m)0.30.20.10-0.1-0.2X
Page 99 and 100: Station D1 (before amplification) a
Page 101 and 102: ending of the tower as shown in Fig
Page 103 and 104: symmetric about the centerline of t
Page 105 and 106: Tensile stress (MPa)800750700650600
Page 107 and 108: 7. Conclusions and RecommendationsB
Page 109 and 110: The vast arrays of acceleration dat
Page 111 and 112: 14. Cunha A, Caetano and Delgado T.
Page 113 and 114: 42. Song, W., Giraldo, D.F., Clayto
Page 115 and 116: Figure A.2 Vertical stiffness and d
Page 117 and 118: A.2 Group Interaction FactorThe cro
Page 119 and 120: For a group of piles with identical
Page 121: Missouri Department of Transportati
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