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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Field Evaluation of Alternative and Cost-Efficient Bridge Approach Slabs</title>
      <link>https://rip.trb.org/View/1301311</link>
      <description><![CDATA[Recently Missouri Department of Transportation (MoDOT) in collaboration with Missouri Transportation Institute (MTI) and the National University Transportation Center (NUTC) funded a study to develop cost efficient alternative bridge approach slab (BAS) designs (Thiagarajan et al. 2010). After surveying the cost and performance of different bridge approach slabs being used by Departments of Transportation (DOT) around the country, performing numerical modeling and simulations, and analyzing cost data, the study has recommended three new BAS designs for possible adoption and implementation by MoDOT. These include: a) 20 feet cast in place (CIP) slab with sleeper slab - for new construction on major roads; b) 25 feet precast prestressed slab with sleeper slab - for replacement and new construction applications on major and minor roads; and c) 25 feet modified BAS without a sleeper slab for new CIP construction on minor roads. Additionally, the use of Controlled Low Strength Materials (CLSM), aka flowable fill, as a backfill material behind bridge abutments under the BAS was suggested as a possibility to solve problematic bridge approach slab issues, such as excessive settlement, loss of support due to erosion, and others. A preliminary short study was performed to evaluate feasibility of producing low cost CLSM mixtures suitable for this application. In this project, researchers propose to collaborate with MoDOT engineers to evaluate the field performance of the BAS designs, recommended by the earlier study, through their implementation on a series of pilot projects. Field performance of the new designs and their impact on construction duration and cost will be evaluated using a variety of methods including visual evaluation, profilograph studies, surveying, field instrumentation, collection of actual cost and duration data from the field engineers, and project close out interviews with the field engineers.]]></description>
      <pubDate>Fri, 07 Mar 2014 01:01:49 GMT</pubDate>
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      <title>Project 2c: Alternative and Cost-Effective Bridge Approach Slabs - UMKC</title>
      <link>https://rip.trb.org/View/1230716</link>
      <description><![CDATA[The goal of this project is to find cost-effective alternative solutions for bridge approach slabs that will be ready for field implementation at the completion of this project. The primary objectives of the proposed study are to: 1) Investigate and recommend alternative design solutions with the aim to reduce the cost of construction of a bridge approach slab, and 2) Develop remedial measures or alternative designs for a replacement. It is clear that the problem of cracking and riding discomfort due to the "bump at the end of the bridge" stems largely from geotechnical considerations. In many instances compaction of soils under uncertain conditions when the bridge is being constructed may not be properly achieved. This study will be focused on cost-effective structural solutions, provided that differential settlements cannot be entirely mitigated by geotechnical solutions.]]></description>
      <pubDate>Thu, 03 Jan 2013 14:04:48 GMT</pubDate>
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      <title>Finite Element Analysis of Concrete Approach Slab on Soil Embankment</title>
      <link>https://rip.trb.org/View/1230340</link>
      <description><![CDATA[Current AASHTO specifications for structural design of bridge approach slabs do not take into account the interaction of slabs with the underlying soil. Consequently, the slabs experience a distress primarily in the form of cracking, also known as "the bump at the end of the bridge" because they are not designed to sustain the effects of differential settlements. Passing of large heavy vehicles over distressed slabs generates impact loads that cause further damages to bridges and pavements and may become a safety concern. In addition, the accumulation of settlement over time necessitates frequent maintenance, thus increasing the whole life cycle costs of bridges and incurring additional costs due to the associated traffic disruptions. While several different suggestions have been proposed for the alleviation of this problem (Stark et. al., 1995; Monley and Wu, 1993; Helwany et al., 2003) none of them have been widely accepted or implemented. It is because of a sheer number of bridges, including 25,620 in Kansas alone, and 590,111 in the U.S. that the current design approach negatively affects the resilience, durability, safety and economy of transportation infrastructure. Kansas has the fourth largest number of bridges, following Texas, Ohio and Illinois. In addition, according to Bakeer et al. (2005) Kansas was also the second state to build the integral bridge in 1935. Today Kansas has about 1,000 integral bridges. This type of a bridge is more sustainable choice than its non-integral counterpart because it boasts multiple advantages. However, the bridge approach settlement in integral bridges is even more significant due to a complex soil-structure interaction. Significant differential settlements occur below the approach slab because integral bridges accommodate thermal expansions and contractions of the deck through the cyclic deformation in the adjacent soil. Devising a design that will enable the approach slabs to sustain larger differential settlements will directly contribute to the increased resilience, longevity, safety and economy of transportation lifelines, thus increasing their overall sustainability rating.]]></description>
      <pubDate>Thu, 03 Jan 2013 13:58:31 GMT</pubDate>
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