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1.3. Seismic instrumentation systemIn seismically active regions such as the NMSZ, acquisition of structural response andnearby free field response data during earthquakes or other extreme loading events, e.g.,blasts, is essential to evaluate current design practices and develop new methodologiesfor future analysis, design, and retrofitting of infrastructure systems. Due to its criticalityand proximity to the NMSZ as well as lack of significant measured ground motions, theBill Emerson Memorial Cable-stayed Bridge and its adjacent area were installed with an84-channel seismic instrumentation system. The so-called ASPEN system was processedand developed by a group comprised of the Federal Highway Administration (FHWA),Missouri Department of Transportation (MoDOT), HNTB Corp., MultidisciplinaryCenter for Earthquake Engineering Research (MCEER), and United States GeologicalSurvey (USGS). The system consists of a total of 84 Kinemetrics EpiSensoraccelerometers, Q330 digitizers, and Baler units for data concentrator and mass storage.These hardware components were designed and installed on the bridge by KinemetricsInc. Antennas were installed on two bridge towers at Pier 2 and Pier 3, at free field siteson the Illinois end of the bridge, and on the central recording building near the bridge, sowireless communication of data can be initiated among various locations as well as fromthe bridge and free field sites to the off-structure central recording building.The accelerometers installed throughout the bridge structure and adjacent free field sitesallow the recording of structural vibrations of the bridge and free field motions at thesurface and down-hole locations. They were deployed such that the acquired data can beused to understand the overall response and behavior of the cable-stayed bridge,including translational, torsional, rocking, and translational soil-structure interactions atfoundation levels. The acquired data also can be used by the researchers and designers tocheck seismic design parameters and to compare dynamic characteristics with those fromactual dynamic responses. The comprehensive understanding of the long-span, cablestayedbridge will benefit other similar bridge seismic design, especially for those alsolocated in the same seismic zone.1.4. Scope of workThe primary goal of this investigation is to evaluate the structural dynamic characteristicsof the Bill Emerson Memorial Cable-stayed Bridge. The objectives of the study are toretrieve peak ground motions at the bridge site and to verify the assumptions made in thestructural design of the bridge. The approach taken to verify the design assumptions is todevelop a well-calibrated FE model of the cable-stayed bridge, and to study the behaviorand load path of the bridge structure. To achieve the objectives above, the scope of workincludes:1. Develop a methodology and necessary tools for automatic compiling of the peakground and structural accelerations.2. Establish a 3-D FE model of the bridge including multi-support excitations andsoil-structure interaction so that realistic behaviors of the bridge can be simulatednumerically. Both the main and approach spans will be modeled with acommercial program (SAP2000) that is suitable for modeling of superstructure,substructure, and pile foundations.6
3. Evaluate the model by conducting sensitivity analysis, checking boundaryconditions and compatibility of various parts of the bridge, and making necessaryengineering judgments. Sensitivity analysis will ensure that the modeling ofvarious parts of the bridge is consistent in terms of member types, geometricaland material properties. Connectivity among various structural members at a jointcould be pretty complicated in a cable-stayed bridge. It needs to be properlymodeled.4. Determine the bridge’s dynamic characteristics such as vibration mode shapes andfrequencies. The dynamic characteristics of the bridge will be identified from themeasured accelerations due to ambient vibration and they will be compared withthe calculated values from the FE model.5. Verify the assumptions used in the design of the bridge structure by understandingthe structural behavior and load path with the well-calibrated FE model when bothground motions and structural responses at critical locations are known.1.5. Significant of this studyA number of long-span bridges exist near the New Madrid Seismic Zone (NMSZ). Manyof these bridges are subjected to direct threats from the NMSZ where the largestcontinental earthquake in the US history occurred in 1811-1812. Service outage of thesebridges due to earthquake-induced failure will not only cause traffic congestion in regionbut also sever the nation’s ground transportation link along the corridor from Californiato New York. The public perception to any of these potential incidences is significant.This study helps understand the seismic behavior of the Bill Emerson Memorial CablestayedBridge under a design earthquake. It identifies key areas and structuralcomponents for inspection of the bridge after a strong earthquake event in the future.The cable-stayed bridge system is unique in several ways, including the combined rockand soil conditions, the new design feature of towers. This study validates some of thedesign assumptions by assessing the integrity of the cable-stayed bridge under apostulated design earthquake based on the acceleration records during a minorearthquake.This study provides a baseline three-dimensional model of the cable-stayed bridge thathas been validated with field measurements. This model can further be used to developdamage detection and health monitoring schemes of the bridge to arrive at the so calledcondition-based inspection of bridge conditions or provide a critical supplement to visualinspection in current practices. The model can also be used to develop and validatecontrol technologies such as those studied by Agrawal et al. (2003) and Dyke et al.(2003).1.6. Organization of this reportThis report is divided into seven major sections. Section 1 gives a general introduction onthe Bill Emerson Memorial Cable-stayed Bridge, the seismic instrumentation system,scope and significance of this study. Section 2 presents a process and methodology toretrieve the peak accelerations in a fixed time window from the continuous data collectedin real time. In Section 3, some of the collected data from the instrumentation system are7
Page 1 and 2: Organizational Results Research Rep
Page 3 and 4: TECHNICAL REPORT DOCUMENTATION PAGE
Page 5 and 6: Executive SummaryOpen to traffic on
Page 7 and 8: 8. All cables behave elastically un
Page 9 and 10: Table of ContentsExecutive summary.
Page 11 and 12: List of Figure CaptionsFigure 1.1 A
Page 13 and 14: Figure 5.30 29 th mode shape (1.032
Page 15 and 16: 1. Introduction1.1. GeneralCable-st
Page 17 and 18: Figure 1.1Artist rendering of the B
Page 19: Expansionand lateralearthquakerestr
Page 23 and 24: 2. Automatic Retrieval of Peak Acce
Page 25 and 26: 2.2.3. Map/Find stationsClicking th
Page 27 and 28: 2.2.5. Displaying seismogramsTo dis
Page 29 and 30: Figure 2.8Directory chooser2.2.6. S
Page 31 and 32: 3.2. Seismic instrumentation networ
Page 33 and 34: The main bridge from Bent 1 to Pier
Page 35 and 36: (a) South side of deck at support o
Page 37 and 38: (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
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When the bridge deck moves up and d
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1.1Frequency (Hz)0.90.70.5BC Case 1
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1.1Frequency(Hz)0.90.70.5Plus 0Plus
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no difference among the three cases
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The FE model of the bridge was vali
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10.6TestFE model0.2-0.20 100 200 30
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1.20.80.40-0.4TestFE model0 100 200
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differences is that the exact locat
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(a) Vertical acceleration time hist
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The FE model of the cable-stayed br
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Displacement (m)0.30.20.10-0.1-0.2X
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Station D1 (before amplification) a
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ending of the tower as shown in Fig
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symmetric about the centerline of t
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Tensile stress (MPa)800750700650600
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7. Conclusions and RecommendationsB
Page 109 and 110:
The vast arrays of acceleration dat
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14. Cunha A, Caetano and Delgado T.
Page 113 and 114:
42. Song, W., Giraldo, D.F., Clayto
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Figure A.2 Vertical stiffness and d
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A.2 Group Interaction FactorThe cro
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For a group of piles with identical
Page 121:
Missouri Department of Transportati
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