This Week's Featured Presentation
Phase Change Materials in Concrete (ACI Spring 2019 Convention, Québec City, QC, Canada) The use of phase change materials in infrastructure has gained significant attention in the recent years owing to its robust thermal performance. This study implements a multiscale numerical simulation framework using finite element analysis to evaluate the influence of Phase Change Materials (PCMs) on the thermal response of concrete pavements in places with significant winter weather conditions such as New England area of the United States. The influence of transition temperature of PCMs, PCM-dosage, environmental and weather conditions are considered in the analysis. The analysis is carried out at different mutually-interactive length scales and the latent-heat associated with different PCMs is efficiently incorporated into the simulation framework. The simulations show significant reductions in the number of freeze-thaw cycles experienced by the pavement in a winter season upon judicious selection of PCM-type and dosage. The numerical simulation framework thus provides efficient means of optimizing the material design of such durable concrete pavements.
August 10 - 16
Load-Rating Strategies for Bridges with Limited or Missing As-Built Information
by Mehrdad Dizaji, University of Virginia; Mohamad Alipour Tabrizi, University of Virginia; Devin K. Harris, University of Virginia; and Osman Eser Ozbulut, University of Virginia
Rating Methods for Defining Performance of Existing Concrete Bridges (ACI Spring 2018 Convention, Salt Lake City, UT) Load rating is the process used in determining the safe load-carrying capacity of a bridge. When available information about a bridge is not sufficient to inform conventional analysis practices, bridge engineers often use engineering judgment to formulate a rational estimate of a bridge’s load rating. This engineering judgement is subjective and can potentially be unconservative, which could pose potential risk to safety or accelerate damage to an overloaded structure. Alternatively, if the rating is too conservative, the result can affect prioritization of maintenance operations and may unnecessarily restrict commerce. This presentation describes an investigation aimed at developing rational engineering approaches for load rating structures within the Virginia Department of Transportation inventory for bridges with insufficient details. The presentation will highlight features of select Structural Identification (St-Id) approaches that were used in the study along with a description of their performance and accuracy. Results demonstrate the benefits and limitations, but also the viability of the proposed method to help VDOT improve the ratings of these structures in a safe, cost-effective manner while also increasing or eliminating postings on some bridges, and thus improving the flow of commerce within the Commonwealth.