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Approximately a quarter of the bridges in the United States are classified as either functionally obsolete or structurally deficient by the United States Department of Transportation (USDOT). As such, transportation agencies are challenged to handle the increasing need of upgrades with limited resources. Accelerated Bridge Construction (ABC) can reduce the construction duration and can decrease the environmental and socio-economic impacts of repair and upgrade activities by minimizing traffic disruptions. As several states are using accelerated construction techniques, a standard guideline would be highly beneficial for these agencies in developing or improving the ABC decision-making process. As problems are often project specific, a decision tool can assist in determining the viability of ABC over traditional construction methods and in selecting appropriate construction and contracting strategies on a case-by-case basis. This paper presents findings of a recent survey with regards to utilization of ABC strategies by state Departments of Transportation (DOTs), and a decision support framework which consists of three models: (1) Analytical Hierarchy Process (AHP) based ABC vs. traditional construction decision-making model; (2) ABC alternatives selection model; and (3) procurement method and contract selection model. The paper also discusses the use of ABC in New York State and describes a New York State bridge project to validate the AHP model. First published online 02 May 2017

Dynamic pile group effect can either increase or decrease the response of pile-supported structures. This paper presents the results of a three-dimensional finite element model of the pile-to-pile interaction that considers the effect of the surrounding soil to determine the dynamic stiffness and damping for vertical end bearing pile groups subjected to a vertical harmonic loading. The results were generated for a wide range of the dimensionless frequency parameter (ao) for a 9 × 9-pile group with three different spacings: two-, four- and six-pile diameter. Both the stiffness and the damping showed an oscillatory behaviour with the dimensionless frequency parameter ao, as well as with the soil shear modulus. In addition, the group efficiency was determined as a function of the pile spacing and the soil shear modulus. The efficiency factor for the stiffness can be as high as 1.15 and as low as 0.7 and for the damping as high as 3.75 and as low as 0.4 as a function of the dimensionless frequency parameter ao. [ABSTRACT FROM AUTHOR]