Seismic Vulnerability Analysis Of Bridges In Mountainous States
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| Author | : Matt Hardman |
| Publisher | : |
| Total Pages | : 34 |
| Release | : 2013 |
| Genre | : Bridges |
| ISBN | : |
Depending on the location, highway bridges can often support considerable amounts of traffic. Due to the limitations on current earthquake forecasting techniques, a normal amount of traffic will also typically remain on a bridge when an earthquake occurs. In addition to traffic, scour effects are also a potential hazard to bridge piers that may simultaneously impact the structural integrity of the bridge together with seismic loads. Although a few studies investigating the combined effect of extreme and service loads have been conducted on long-span bridges or in high-seismic zones, the studies on typical short- and medium-span bridges in low and moderate seismic zones are rare. A general dynamic simulation methodology is introduced to study the combined realistic service and extreme loads on short- and medium-span bridges. Following the introduction of the methodology, a numerical study investigating the seismic performance of a typical highway bridge in mountainous states is carried out. The bridge is subjected to different combinations of traffic, seismic, and scour and the effects on the structural performance of the bridge are investigated. The bridge, including both superstructure and substructure, is modeled in detail using SAP2000 to accommodate the goals of this study. The traffic load is considered through dynamic interaction analysis of vehicles in the simulated stochastic traffic flow. Through studying the bridge performance under various combined extreme and service loads, findings are made about controlling cases for different bridge responses and the validity of the traditional superposition approach with consideration to load combinations is also discussed. As the initial effort studied the bridge performance under multiple service and extreme loads, this study sheds some light on more comprehensive studies for the future.
| Author | : United States. General Accounting Office |
| Publisher | : |
| Total Pages | : 44 |
| Release | : 1992 |
| Genre | : Bridges |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 28 |
| Release | : 2002 |
| Genre | : Bridges |
| ISBN | : |
This executive summary gives an overview of the results of FHWA Contract DTFH61 92 C 00112, Seismic Research Program, which performed a series of special studies addressing the seismic design of new construction. The objectives of this project were to perform a series of special studies pertaining to the seismic vulnerability of highway structures, and to develop technical information on which future specifications for the seismic design of bridges could be based. This project divided work into 5 areas and 13 tasks, focusing on the following elements: review of current seismic design criteria, the seismic hazard exposure of the American highway system, foundation design and soil behavior, structural design, structural analysis and response, the relative importance of specific bridges and an assessment of the impact of current and recently completed research. The Seismic Research Program had a national focus, and aimed in part to address the differences in seismicity, bridge types, and typical design details between the central and eastern United States (CEUS) and those previously studied in California and the western United States. In many cases, west coast design practices required considerable modification before implementation in the CEUS. The project resulted in 34 research reports, of which 31 are summarized in this document. Seventeen of the reports have been published as National Center for Earthquake Engineering Research (NCEER) or Multidisciplinary Center for Earthquake Engineering Research (MCEER) reports. The research agencies final reports for the other taks are available from MCEER upon request.
| Author | : |
| Publisher | : DIANE Publishing |
| Total Pages | : 76 |
| Release | : 1993-07 |
| Genre | : Technology & Engineering |
| ISBN | : 9781568069807 |
Focuses on threats that earthquakes pose to the nation1s bridges.
| Author | : EQE Engineering Consultants |
| Publisher | : |
| Total Pages | : |
| Release | : 1997 |
| Genre | : Bridges |
| ISBN | : |
| Author | : EQE Engineering Consultants |
| Publisher | : |
| Total Pages | : |
| Release | : 1997 |
| Genre | : Bridges |
| ISBN | : |
| Author | : John Edward Lens |
| Publisher | : |
| Total Pages | : 296 |
| Release | : 2019 |
| Genre | : Bridges |
| ISBN | : |
The U.S. Congressional Research Service issued a report for Congress in May 2016, entitled "Earthquake Risk and U.S. Highway Infrastructure: Frequently Asked Questions" which highlighted the absence of a national database on the status of seismic vulnerability of bridges or other infrastructure, and thus no estimate of costs to retrofit vulnerable bridges. Low to moderate seismicity regions exist in each of the continental United States, with over 30 states having mostly or entirely low-to-moderate seismicity. Resources at state transportation agencies and municipalities are focused on higher seismicity regions, creating a gap in quantifying the system-wide seismic vulnerability despite an overall aging bridge inventory, much of which was built before current seismic design standards. This research addressed this data gap and reduces barriers to quantifying seismic vulnerability of existing bridges in low-to-moderate seismicity regions. The work included nonlinear dynamic numerical modeling of typical multiple span bridge configurations in both pristine and deteriorated conditions, by subjecting them to seventy ground motions across four low-to-moderate seismic hazard levels, to evaluate their seismic performance. These typical bridge configurations represent over 160,000 bridges, which comprise 55% of the multiple span bridges nationwide. The research results indicate that there is an overall low probability of significant seismic damage to these typical bridges in such regions. The results also show that current seismic hazard thresholds used for the design of new bridges, and for retrofit of existing bridges, which provide the basis for exempting some bridges from specific seismic analysis and design, can underestimate the expected seismic forces. Those results can be used to refine those exemption thresholds to provide appropriate protection against potential seismic damage in those cases. The study results also formed the basis for a system-wide rapid seismic vulnerability screening algorithm developed for the Vermont bridge inventory, which is applicable to other states with low to moderate seismicity regions.
| Author | : Xuan Guo |
| Publisher | : |
| Total Pages | : 255 |
| Release | : 2014 |
| Genre | : Bridges |
| ISBN | : |
Bridges are a vital infrastructure component of the transportation networks in both rural and urban areas. Damaged or destroyed bridges can affect the reliability and resilience of transportation networks that are critical to human life, economical activities, and the social sustainability at large. Understanding how natural hazards affect the life-cycle performance of bridge systems will lead to improved preparedness prior to extreme disasters and benefit the society ultimately. Among many natural events, flood-induced foundation scour has been recognized as a leading cause of bridge failure in the United States. The distinct feature of flood-induced scour is that it may last during the rest of bridge's service life once it is formed around a bridge foundation. Intuitively, the threat may be potentially more severe if the permanent scour is combined with other hazards, such as earthquakes. However, the combined effects of such multiple hazards are not clearly understood to date. It is thus meaningful to investigate the effects of multi-hazard earthquake and scour on the seismic performance of river-crossing bridges. The general objective of this dissertation is to assess the seismic vulnerability of bridge structures considering flooding-induced scour in a general multi-hazard context. To meet this objective, five related research problems are defined in this dissertation. Correspondingly, scientific answers and technical solution frameworks are developed in this dissertation. The dissertation directly contributes to the multi-hazard assessment methodology with an emphasis in flood-induced scour and earthquake hazards. Specifically, the dissertation directly resolves the practical challenge of evaluating the effects of bridge scour on the seismic performance of river-crossing bridges in terms of theoretical frameworks, numerical procedures, and case study-based findings. Future research directions along the line of multi-hazard bridge performance research with an emphasis of hydro- and seismic-impacts are pointed at the end of the dissertation.
| Author | : Abdollah Shafieezadeh |
| Publisher | : |
| Total Pages | : 204 |
| Release | : 2009 |
| Genre | : Bridges |
| ISBN | : |
Much of Utah's population dwells in a seismically active region, and many of the bridges connecting transportation lifelines predate the rigorous seismic design standards that have been developed in the past 10-20 years. Other states in the west have instituted seismic retrofit programs in response to damage to transportation networks in past California earthquakes. In a parallel report, seismic retrofit guidelines were developed for Utah based on the Seismic Retrofitting Manual for Highway Structures published by FHWA. In this report, representative case study bridges are evaluated in detail using the guidelines. The case study evaluations include the following for each bridge: 1- selection and presentation of analysis method, 2- development of numerical model in LARSA 4D and/or additional programs as needed, 3- evaluation of the seismic response of the unretrofitted bridge, 4- design of a possible retrofit scheme. The bridges evaluated include a four-span simply supported prestressed concrete girder bridge, a four-span continuous concrete T-beam, and an eight-span curved steel girder bridge with in-span pin and hanger joints.
| Author | : Sungyeop Jung |
| Publisher | : |
| Total Pages | : |
| Release | : 2000 |
| Genre | : |
| ISBN | : |
