Size: 470 MB | Quality: 720 x 480 | Format:AVI | Year:2004 | Video Codec: MPEG Layer-3 | Language: English
In 1955, two ferries sank along the Akashi Strait, Japan, killing 168 children. It led to a 30 year research on designing a bridge that would link the Awaji Island to Kobe; the bridge would also have to be able to withstand severe earthquakes and typhoons, a norm in that area. In 1988, Japan began construction of the world's longest, highest and most expensive suspension bridge, the Akashi Kaikyo Bridge. The episode presents a stage by stage look at the construction of the suspension bridge, and the obstacles faced in its construction, including the Kobe earthquake in 1995.less
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Author: Hay, Thomas R | Size: 1.10 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2008 | pages: 216
Inspection of steel bridge piles on a regular basis for the presence of defects is essential for the long-term safety of bridge infrastructure over water. Currently, these inspections are done visually and in the case of submerged piles, divers perform these inspections. Current pile inspections are performed by divers according to the National Bridge Inspection Standards and are dependent on inspector training, skill and experience. In many cases, significant sections of pile can not be visually inspected since they are submerged in environments that prevent visual inspection, such as swampy waters and river beds. Based on this feedback from railway bridge field engineers, there is a requirement for affordable pile inspection technology capable of providing feedback on pile wall loss. The ideal technology would be able to inspect submerged pile remotely from easy-to-access pile locations. The objective of this Innovations Deserving Exploratory Analysis (IDEA) project was to study the pile wall loss detection and characterization potential of long-range ultrasound (LRUT). Quantitative readings on remaining wall would be used to estimate pile remaining life and the load rating for the bridge. Laboratory studies were carried out to investigate the effectiveness of LRUT in detecting several types of manufactured defects in dry as well as H-piles submerged in water. In the laboratory tests, LRUT was able to detect manufactured defects, such as wall loss, through spliced and braced pile. Field testing was carried out on dry H-pile on a Norfolk Southern bridge in Mississippi and these data were used to develop Distance-Amplitude Correction (DAC) curves to quantify the wall loss (in ranges of 100%, 75%, 50%, and 25% wall loss). These ranges were established based on feedback from Norfolk Southern Railway and the performance limitations of the technology. Field testing on submerged H-pile was undertaken on a Norfolk Southern bridge in North Carolina. Of the eighteen LRUT measurements taken, slightly more than half fell within the established accuracy requirements, based on comparisons with actual measurements taken by divers.. Possible sources for the differences include the location at which the diver made the measurement, the severely-eroded pile surface above water, on which the electromagnetic acoustic transducer was mounted, inability of the current prototype to account for multiple inline wall losses, welded braces absorbing significant amounts of the ultrasound, and LRUT measurement error. As a direct result of this project, WavesinSolids LLC has developed the core technology to launch a commercial product and inspection service. Improvements in this core technology are underway to address the problems identified in the field tests.
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2009 Design of Reinforced Masonry Structures (6th)
Publisher: The Masonry Society; 6th edition (2009)
Language: English
ASIN: B007K3BA22
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PROCEDURES FOR EVALUATING CORROSION-INHIBITING ADMIXTURES FOR STRUCTURAL CONCRETE
Author: Thompson, N G Yunovich, M Lankard, D R | Size: 2.12 MB | Format:PDF | Quality:Original preprint | Publisher: National Cooperative Highway Research Program | Year: 2000 | pages: 216
The objectives of this research were to (1) develop procedures for evaluating and qualifying corrosion-inhibiting admixtures (CIAs) and (2) recommend performance criteria for their acceptance. Phase I work included a literature review of CIAs, the review of test procedures presently used for evaluating CIAs, and the development of a laboratory test plan for evaluating CIAs. In Phase II, the laboratory test plan was executed and performance criteria for qualifying an admixture as a CIA were developed.
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MANUALS FOR THE DESIGN OF BRIDGE FOUNDATIONS: SHALLOW FOUNDATIONS, DRIVEN PILES, RETAINING WALLS AND ABUTMENTS, DRILLED SHAFTS, ESTIMATING TOLERABLE MOVEMENTS, AND LOAD FACTOR DESIGN SPECIFICATIONS AND COMMENTARY
Author: Barker, R M Duncan, J M Rojiani, K B Ooi, PSK Tan, C K Kim, S G | Size: 20.68 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 1991 | pages: 228 | ISBN: 0-309-04866-4
This report documents and presents the results of a forty-two month study to develop load factor design procedures for highway bridge foundations. The findings of the study are presented in a new draft AASHTO Design Code and Commentary for foundations and retaining walls, and in five engineering manuals, and a separate report on code calibration. The engineering manuals address (1) design of driven pile foundations, (2) design of drilled shaft foundations, (3) design of shallow footing foundations, (4) design of retaining walls and abutments, and (5) estimation of tolerable settlements of structures. The manuals present state-of-the-art design methods, and illustrate their use through examples. This study shows that the foundations of bridges and other structures can be designed effectively using load factor design procedures, and it establishes procedures for load factor design of foundations.
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Spread footings are most often less expensive than deep foundations. In an effort to improve the reliability of spread footings, this research project was undertaken. The results consist of: (1) a user friendly microcomputer data base of spread footings, case histories and load tests; (2) the performance of five large scale square footings in sand; (3) an evaluation of the current accuracy of settlement and bearing capacity prediction methods; (4) observations on the scale effect, the zone of influence, the creep settlement, and soil heterogeneity; (5) a new and simple method to predict the complete load settlement curve for a footing as well as several correlations; and (6) evaluation of the WAK test, a dynamic test for spread footings.
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SEISMIC PERFORMANCE AND RETROFIT OF MULTI-COLUMN BRIDGE BENTS
Author: McLean, D I Kuebler, S E Mealy, T E | Size: 2.23 MB | Format:PDF | Quality:Original preprint | Publisher: Washington State University, Pullman | Year: 1998 | pages: 58
This study investigated retrofitting measures for improving the seismic performance of existing multi-column bridge bents. Experimental tests were conducted on 1/4.5-scale footing and column assemblages which incorporated details that were selected to represent deficiencies present in older bridges. Various retrofit measures for the bents were evaluated. The specimens were subjected to increasing levels of cycled inelastic lateral displacements under constant axial load. Specimen performance was evaluated on the basis of load capacity, displacement ductility, strength degradation and hysteretic behavior. Tests on the as-built specimens resulted in severe cracking in the footings due to insufficient joint shear strength in the column/footing connections. However, due to structural redundancy, the bents continued to resist lateral loads until eventual bent failure occurred as a result of flexural hinge degradation in the columns. Measures developed previously for retrofitting single-column bent bridges were found to be effective in improving the performance of the footings and columns. When all substructure elements were retrofitted, a ductile bent response was obtained. Retrofitting only some of the substructure elements resulted in incremental improvements in performance according to the number of elements retrofitted. While extensive damage occurred in the unretrofitted elements, the damaged regions continued to transfer forces during testing, enabling a stable bent response until failure occurred within one or more of the retrofitted elements. The addition of a stiff link beam just above the footings was found to be effective in preventing damage in the footings during testing, and a reasonably ductile bent response was achieved. Because the link beam retrofit may not require retrofitting of the footings, this strategy may be a very cost-effective approach for retrofitting multi-column bents.
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FIELD AND LABORATORY PERFORMANCE EVALUATION OF SPREAD FOOTINGS
Author: Sargand, S M Hazen, G A | Size: 9.51 MB | Format:PDF | Quality:Original preprint | Publisher: Ohio University, Athens | Year: 1999 | pages: 358
The performance of five highway bridge structures, located in Ohio and supported by spread footings on cohesionless soils or cohesive soils, was monitored in the field throughout construction and under service conditions. The performance of these structures was also examined through centrifuge modeling in the laboratory. Factors used in evaluating these bridges were overall settlement, tilting of abutment walls/pier columns, and pressure distribution under the footings. Field and experimental measurements were then compared against estimates made by selected geotechnical methods. None of the spread footings in these five bridge structures experienced an average settlement of more than 2 in. (5 cm) prior to service load application. Contact pressure monitored at the footing/bearing soil interface in the field remained less than 40 psi (276 kPa) and was generally close to the theoretical estimate. Poorer agreement resulted between the measured and predicted abutment wall tilting. None of the six geotechnical methods for predicting settlement of footings on cohesionless soils was accurate in all cases. The method proposed by Hough appeared to be the best. Standard methods used to estimate immediate and time dependent consolidation settlements were reasonably accurate when compared to field data. Centrifuge testing techniques provided settlement results superior to those predicted by any of the six geotechnical methods. One limitation of centrifuge testing, however, is the simulation of complex subsurface conditions in the laboratory.
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PERFORMANCE OF GEOSYNTHETIC-REINFORCED WALLS SUPPORTING THE FOUNDERS/MEADOWS BRIDGE AND APPROACHING ROADWAY STRUCTURES
Author: Abu-Hejleh, N Zornberg, J G Wang, T McMullen, M Outcalt, W | Size: 5.78 MB | Format:PDF | Quality:Original preprint | Publisher: Colorado Department of Transportation | Year: 2001 | pages: 162
The Founders/Meadows structure is the first major bridge in the United States built on footings supported directly by geosynthetic-reinforced soil (GRS) walls, eliminating the traditional use of deep foundations altogether. The performance of the front GRS walls, which support the bridge structure and embankment behind the abutment wall, was investigated by collecting data for the movements of the wall facing, settlement of the bridge footing, distributions of the vertical earth pressures and geogrid tensile strains inside the front GRS walls, and lateral earth pressures against the wall facing. Monitoring data was collected during six construction stages and while the structure was in service. This report provides a summary and analysis of the collected data, assessment of the performance and design of the front wall, and recommendations for design and construction of future GRS abutments. Compaction operations created large loads in the reinforcements and against the wall facing during interim construction stages of the front wall. The front GRS walls showed excellent performance because: (i) the monitored movements were significantly smaller than those expected in design or allowed by performance requirements, (ii) post-construction movements and geogrid strains became negligible after an in-service period of 1 year, (iii) measured loads in the reinforcements, connections, and on the wall facing were less than or around 50% of those estimated in the design, (iv) there is not any potential for overturning the structure (due to the flexibility of GRS wall system, resulting in the reduction of loads developed behind and against the wall facing), and (v) the measured bearing pressures were well below the allowable soil bearing capacity. The design employs a high creep reduction factor for the geogrid reinforcements although little if any long-term creep was observed.
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EVALUATION OF FEM ENGINEERING PARAMETERS FROM INSITU TESTS
Author: Townsend, F C Anderson, J B Rahelison, L | Size: 7.34 MB | Format:PDF | Quality:Original preprint | Publisher: University of Florida, Gainesville | Year: 2001 | pages: 265
The purpose of this study was to take a critical look at insitu test methods (SPT, CPT, DMT, and PMT) as a means for developing finite element constitutive model input parameters. The first part of the research examined insitu test derived parameters with laboratory triaxial tests at three sites: Saunder's Creek, Archer Landfill, and SW Recreation Center. The triaxial tests on these sands were used to develop baseline input parameters. These parameters were verified by simulating the triaxial tests using two finite element codes. From these comparisons, the following conclusions were drawn: (1) FEM simulations of triaxial test stress-strain curves produced excellent results; (2) The hardening models (PLAXIS - Hardening Soil and PlasFEM - Sandler Dimaggio) simulated the nonlinear behavior better than the Mohr-Coulomb or Drucker-Prager models; (3) In general, E sub 50 triaxial test modulus values agreed with those estimated from DMT and PMT unloading tests; and (4) FEM simulations of field PMT curves using triaxial test based parameters were unsuccessful. The second phase of this study was to predict the deformations of a cantilevered sheet pile wall (unloading case), and the deformations of a 2-m diameter shallow footing (loading case). Conventional analysis methods were compared with FEM using insitu test derived input parameters. Conclusions were: (1) Conventional analyses (CWALSHT) under-predicted wall deformations unconservatively, while wall deflections were accurately predicted using the Hardening Soil Model with input parameters estimated from SPT correlations and "curved matched" PMT values; (2) Fundamentally, the stress history of a soil profile, i.e., OCR or preconsolidation pressure, must be known for any settlement prediction either using conventional or finite element methods; (3) Of the conventional methods for estimating settlements (CSANDSET), only the SPT based D'Appolonia, and Peck and Bazaraa methods provided reasonable estimates of the observed settlement; (4) The conventional DMT method, which correlates OCR values, slightly overestimated measured settlements; (5) None of the insitu test derived input parameters (SPT, CPT, DMT, and PMT) coupled with FEM Mohr-Coulomb or Hardening Soil models, accurately predicted the shallow footing settlements.
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