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From page 203... ... 203 CHAPTER 5. Methodology for Scour Depth Prediction 5.1 Introduction Applications of the findings of the research are summarized in this chapter. Read the entire page →
From page 204... ... 204 Table 5-1. Summary of proposed combined scour equations. Read the entire page →
From page 205... ... 205 Table 5-1, continued Notes: 1. A= abutment scour, L= lateral contraction scour, V= vertical contraction scour, P= pier scour, WWA = wingwall abutment, STA = spill-through abutment, LSA = long setback abutment, I = interactive abutment and contraction scour in floodplain, II = interactive abutment and contraction scour in main channel, III = interactive abutment, contraction, and pier scour in floodplain, IV = interactive pier and vertical contraction scour. Read the entire page →
From page 206... ... 206 Min. Read the entire page →
From page 207... ... 207 Category II. Abutment/Lateral Contraction Scour with or without Vertical Contraction Scour for short setback (SSA) Read the entire page →
From page 208... ... 208 1. Scour Category IIIa, where the pier is situated in the zone of influence of the abutment/lateral contraction scour hole. Read the entire page →
From page 209... ... 209 Scour Category I: Calculate abutment/contraction scour using Eq. (4‐8) Scour Category II: Calculate abutment/contraction scour using Eq. (4‐10) Read the entire page →
From page 210... ... 210 -6 -4 -2 0 2 4 x (ft) Read the entire page →
From page 212... ... 212 symbols. The ineffective areas are valid for free flow and submerged orifice flow but they become active or effective for overtopping flow. Read the entire page →
From page 213... ... 213 Based on a risk analysis, the pertinent design discharges of interest for scour calculations are Q1 = 16,000 cfs (453 m3/s) in free flow, Q2 = 23,000 cfs (652 m3/s) Read the entire page →
From page 214... ... 214 5.4.2 Water Surface Profiles from HEC-RAS Water surface profiles PF1, PF2, and PF3 were computed for Q1, Q2, and Q3 using HEC-RAS v. Read the entire page →
From page 215... ... 215 Table 5-2. Water surface profile output data for all three discharges (Profile Summary Table) Read the entire page →
From page 216... ... 216 The mean velocity in the left floodplain in the approach flow section is 1.48 ft/s (0.45 m/s) , and in the main channel it is 4.81 ft/s (1.47 m/s) Read the entire page →
From page 217... ... 217 Table 5-5. Detailed cross-section output at RS 1185 just downstreamof bridge for PF1 (Q1) Read the entire page →
From page 218... ... 218 In the following example problem calculations, the values of Yf2max or Ym2max are determined from the proposed combined scour prediction equations, and they represent the vertical distance below the reference tailwater elevation (W.S. Read the entire page →
From page 219... ... 219 No other scour components should be added to this estimate regardless of whether there are piers or not because the piers have negligible influence on the maximum abutment/contraction scour depth. Step 3 Yes, there are piers, so proceed to calculate maximum scour at the upstream face of the piers. Read the entire page →
From page 220... ... 220 Step 4 (Pier #2) Calculate Lp/Yf1 for Pier #2: 3.17 39.4 76 1 2  f p Y L Step 5 (Pier #2) Read the entire page →
From page 221... ... 221 No other scour components should be added to this estimate regardless of whether there are piers or not because the piers have negligible influence on the maximum abutment/contraction scour depth. Step 3 Yes, there are piers, so proceed to calculate maximum scour in front of the piers. Read the entire page →
From page 222... ... 222   5.-5 Table See m) Read the entire page →
From page 223... ... 223 same because the pier is isolated from the influence of the abutment in the NCHRP 24-37 method, and because there is no lateral contraction scour predicted by HEC-18. As a result, only pier scour is represented at Pier #2 by both methods. Read the entire page →
From page 224... ... 224 Figure 5-10. HEC-RAS scour output with depiction of predicted scour holes using HEC-18 methods. Read the entire page →
From page 225... ... 225 Table 5-7. Bridge Scour; River=Flat Creek; Reach= Main Stem; RS = 1225 BR (HEC-RAS) Read the entire page →
From page 226... ... 226 5.4.4 Scour Calculations for Submerged Orifice Flow (Q2) and Overtopping Flow (Q3) Read the entire page →
From page 227... ... 227 Table 5-8. Variables for scour calculations for Q2, submerged orifice flow, and Q3, overtopping flow, in left overbank. Read the entire page →
From page 229... ... 229 Finally, for the right abutment, we have Step 1 (right abutment) Read the entire page →
From page 230... ... 230 5.4.5 Application Considerations This study is based on extensive laboratory experiments, and it has been verified with some field data and data from experiments of others. The experiments were conducted with realistic compound channel and bridge geometry based on typical prototype bridge crossings, and they included both clear-water and live-bed scour as well as free, submerged orifice, and overtopping flows. Read the entire page →
From page 231... ... 231 Although the experiments performed in this research showed essentially no difference between wingwall and spill-through abutments with respect to maximum scour depths, additional confirmation may be useful. Experiments by Sturm (2006) Read the entire page →

From page 203...

... 203 CHAPTER 5. Methodology for Scour Depth Prediction 5.1 Introduction Applications of the findings of the research are summarized in this chapter.