2013 Session: 728

• Assessment of Effects of Pier Configurations on Flow Pattern and Scour: Computational Fluid Dynamics Modeling Approach
  Abstract: Flow past piers with different configurations are modeled using three dimensional Computational Fluid Dynamics (CFD) method. The effects induced by different cross-sectional shapes (circular, square, diamond and lenticular), different aspect ratios and different attack angles are studied. The flow patterns including the horseshoe vortex, wake vortex and the vertical flow in front of the pier are analyzed for each configuration; the maximum values of bed shear stress and its overall distribution patterns around the piers with different configurations are also focused on for analysis. It is founded that pier shapes affect the flow pattern bed shear stress distribution pattern dramatically; aspect ratio does not affect the maximum shear stress and the overall pattern of the shear stress whereas it does influence the interaction between the vortex structures; the effect of attack angle is obvious and the degree of such influence also depends on the aspect ratio. An expression based on the concept of effective width is proposed to evaluate the combination effect of the aspect ratio and the attack angle on the maximum shear stress. The findings in this project are also related to the scour patterns around piers to gain some insights into the scour mechanism; possible applications of the CFD approach into practical engineering areas are also discussed, such as in initial scour rate estimation for bridge risk analysis and design guidance for bridge scour countermeasures and monitoring plans.
  Authors: Tao, Junliang; Gao, Quan; Yu, Xiong
  Authors: Tao, Junliang; Gao, Quan; Yu, Xiong
  Year: 2013
  Document Type: Paper
  Subject: Bridges and Other Structures; Design; Hydraulics and Hydrology; Pavements
  Session: 728
  Paper Number: 13-2840
• Framework for Numerical Simulation of Bridge Scour Focusing on Improvements of Sediment Transport Models
  Abstract: Bridge scour is a complicated process involving the interactions between flow and bridge piers and between flow and bed sediment. The existing numerical studies often coupled different sediment transport models to a turbulence flow model to simulate the scour process. The influence of the turbulence fluctuation and the lift force are not incorporated in the traditional sediment models. In this paper, we proposed a framework to evaluate the performances of different sediment transport models. Specifically, the sediment transport equations are given an in-depth study and a new modification method to the sediment models to include the above mentioned influences was proposed based on a comprehensive review. In this framework, the flow domain will be solved using a URANS approach with a k-? turbulence closure model; the sediment transport models (traditional and modified) will be coupled with the flow domain using the arbitrary Lagrangian-Eulerian method.
  Authors: Tao, Junliang; Yu, Xiong
  Authors: Tao, Junliang; Yu, Xiong
  Year: 2013
  Document Type: Paper
  Subject: Bridges and Other Structures; Design; Hydraulics and Hydrology; Pavements
  Session: 728
  Paper Number: 13-2852
• Real-Time Monitoring of Bridge Scour with Magnetic Field Strength Measurement
  Abstract: Scour was responsible for most of the U.S. bridges that collapsed during the past 40 years. The maximum scour depth is the most critical parameter in bridge design and maintenance. Due to scouring and refilling of river-bed deposits, existing technologies face a challenge in measuring the maximum scour depth during a strong flood. In this study, a new methodology is proposed to integrate passive sensors into the process of bridge scour for real time monitoring during a flood event. Towards this end, a permanent magnet can be embedded in a natural rock to function as a passive sensor, which is herein referred to as a smart rock. The smart rock can be designed such that, once deployed around a bridge pier, it continually falls into the bottom of a gradually growing scour hole and thus registers the maximum scour depth with magnetic field strength measurements. Specifically, this paper discusses the societal needs for bridge scour monitoring, demonstrates the concept and the working principle of smart rocks, and summarizes the findings from various calibration and validation tests recently conducted at Missouri University of Science and Technology and at Turner-Fairbank Highway Research Center. It was demonstrated that the magnetic field strength can be strongly correlated with the increase of scour depth over time. Properly designed smart rocks fell into and remained at the bottom of a scour hole, providing critical data in the process of scour development.
  Authors: Chen, Genda; Schafer, Brandon; Lin, Zhibin; Huang, Ying; Suaznabar, Oscar; Shen, Jerry
  Authors: Chen, Genda; Schafer, Brandon; Lin, Zhibin; Huang, Ying; Suaznabar, Oscar; Shen, Jerry
  Year: 2013
  Document Type: Paper
  Subject: Bridges and Other Structures; Design; Hydraulics and Hydrology; Pavements
  Session: 728
  Paper Number: 13-4235
• Flow Characteristics of Permeable Pavements by Water Demand and Supply
  Abstract: Permeable pavement is one of the widely used methods to recover the city¡¯s water circulation. The advantages of using permeable pavement is storage of rainwater, reduction of runoff, out-flow delay, and decrement of peak out-flow. Most of the cases out-flow characteristics of different types of permeable pavements were explained focus on runoff coefficient or the relationship between runoff and infiltration rate. With convenient theories which can explain out-flow characteristics and compare different pavement system considering water balance have been insufficient. In this study, an empirical model cumulative water flow versus time concept, is suggested to explain characteristics of out-flow of permeable pavement. This model is suggested to define and explain the variable by accumulating runoff at surface and outflow at subsurface over time that relates to accumulated rainfall. Through this model advantages of different permeable pavement can be compared and explained through rainfall simulation experiment.
  Authors: Cho, Yoon-Ho; Lin, Wuguang; Park, Dae-Geun
  Authors: Cho, Yoon-Ho; Lin, Wuguang; Park, Dae-Geun
  Year: 2013
  Document Type: Paper
  Subject: Bridges and Other Structures; Design; Hydraulics and Hydrology; Pavements
  Session: 728
  Paper Number: 13-3867