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

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0.053 x 10-3 Frequency(Hz)Acceleration (cm/s 2 )0.040.030.020.010-0.01-0.02-0.03-0.04Amplitude2.521.510.5-0.050 10 20 30 40 50 60 70 80Time(s)(a) Acceleration time historyFigure 6.400 2 4 6 8 10 12 14 16 18 20(b) FFTVertical rock motion at Station D10.065 x 10-3 Frequency(Hz)Acceleration (cm/s 2 )0.040.020-0.02-0.04-0.06Amplitude4.543.532.521.510.5-0.080 10 20 30 40 50 60 70 80Time(s)(a) Acceleration time historyFigure 6.500 2 4 6 8 10 12 14 16 18 20(b) FFTTransverse rock motion at Station D10.067 x 10-3 Frequency(Hz)0.046Acceleration (cm/s 2 )0.020-0.02Amplitude5432-0.041-0.060 10 20 30 40 50 60 70 80Time(s)(a) Acceleration time historyFigure 6.600 2 4 6 8 10 12 14 16 18 20(b) FFTLongitudinal rock motion at Station D180
The FE model of the cable-stayed bridge was subjected to the three-component groundmotions of each earthquake specified in Table 6.1 as well as the rock motions of the May1 2005 earthquake at the bridge site. The peak deflections in three directions at midspanof the bridge were obtained under each earthquake. They are listed in Table 6.2. Theresponse time histories at midspan of the bridge for different earthquake records aredepicted in Figures 6.7 to 6.10.Table 6.2Peak displacement at midspan of the bridge (mm)Earthquake Longitudinal Transverse VerticalMexico City 21.40 389.7 129.2El Centro 58.00 176.9 63.10Pacoima 144.0 82.00 253.0Station D1-36.65×10-36.73×10-32.39×10From Table 6.2, it can be seen that the peak displacement at midspan of the main bridgeunder the Mexico City earthquake is the largest in transverse direction, though the PGAof the Mexico City earthquake is the lowest among the three earthquake records in Table6.1. In fact, both transverse and vertical peak displacements are higher that those underthe El Centro earthquake. These results indicate the significance of frequency contents inground motion records. A closer examination on the ground motions appears that thedominant frequency of the Mexico City earthquake is much lower than that of the ElCentro earthquake. The frequency bandwidth is much narrower than that of the ElCentro. As a result, almost all modes of vibration of the cable-stayed bridge that resonatewith the dominant frequency of the Mexico City earthquake are in vertical and transversedirections. This results in larger displacements in vertical and transverse directions. Onthe other hand, the dominant frequency of the EL Centro earthquake corresponds tohigher modes of vibration of the cable-stayed bridge, leading to smaller amplifications inpeak displacements. For the same reason, even though the Pacoima earthquake issignificantly stronger, it still induces a smaller maximum value of the peak displacementsthan that of the Mexico City earthquake. The same argument is true when the peakdisplacements due to the El Centro and Pacoima earthquakes are compared. Although thePGA of the Pacoima earthquake is several times of that of the El Centro, the maximumdisplacements induced by them are in the same order.It should be noted that the earthquake records at Station D1 are very weak, and themaximum response caused by this earthquake is thus small. Under the Mexico City, ElCentro, and Arkansas earthquakes, the maximum response occurs in the transversedirection while it occurs in vertical direction under the Pacoima earthquake. Thisindicates that the maximum response does not necessarily occur in a certain direction, butdepends on the characteristics of earthquake ground motions.81
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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
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The seismic responses at the top (T
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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 and 90: 1.20.80.40-0.4TestFE model0 100 200
Page 91 and 92: differences is that the exact locat
Page 93: (a) Vertical acceleration time hist
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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