Bridge Hydraulic Analysis Tool

Bridge Hydraulic Analysis Tool - Worksheet

Yarnell Method

1. Flow Conditions
Hydraulic Method	Yarnell (Empirical) Energy (Standard Step) Momentum WSPRO (FHWA)
Design Discharge (Q)		m³/s
Tailwater Mode	Compute Normal Known Depth
Known Tailwater (y₃)		m

2. Channel Geometry
Shape	Rectangular Trapezoidal Trapezoidal with Berm
Bottom Width (B)		m
Side Slope (z:1 H:V)		-
Berm Elevation (y_b)		m
Berm Width (each side)		m
Manning's n		-
Channel Slope (S)		m/m

3. Bridge & Pier Geometry
Roadway Elev		m
Low Chord Elev		m
Pier Shape Coefficient (K)	Semicircular (0.90) Twin-Cylinder (1.05) Square Nose (1.25) Square + Debris (2.50)
Pier Drag Coefficient (Cd)		-
WSPRO Discharge Coeff (C)		-
Number of Piers		each
Pier Width		m
Include Pier Footings
Footing Width		m
Footing Thickness		m
Top of Footing Elev		m
Abutment Encroachment (each side)		m
High Flow Params (Auto-Switches Over Low Chord)
Pressure Orifice Coeff (Cd)		-
Weir Flow Coeff (Cw)		m^0.5/s

4. Pier Scour Analysis
Scour K₁ (Nose Shape)	Round / Cylinder (1.0) Square Nose (1.1) Sharp Nose (0.9)
Scour K₂ (Angle of Attack)
Scour K₃ (Bed Condition)	Clear-Water / Plane (1.1) Small Dunes (1.2) Large Dunes (1.3)
Scour K₄ (Bed Soil / Armoring)	Sand / Silt / Clay (1.0) Gravel / Light Armor (0.8) Cobbles / Heavy Armor (0.5)

* Highlighted cells require user input. Channel bed elevation is assumed to be 0.0.

Calculated Results Summary
Upstream Depth (y₁)	0.00 m	Pier/Abut Head Loss (Δh)	0.00 m	Local Pier Scour (yₛ)	0.00 m
Bridge Velocity (V₂)	0.00 m/s	Freeboard Clearance	0.00 m	Flow State & Condition	0.00 SUBCRITICAL

Profile Schematic View

Cross-Section View

Rating Curve (Q vs y₁)

Scenario Analysis Table
Scenario Flow	Discharge (m³/s)	y₁ (m)	State	V₂ (m/s)	Freeboard (m)	Scour (m)

Theoretical Background
References
Yarnell, D. L. (1934). "Bridge Piers as Channel Obstructions." Tech. Bulletin No. 442, USDA. FHWA HEC-18 (5th Ed). "Evaluating Scour at Bridges." U.S. DOT. FHWA HDS-1 (4th Ed). "Hydraulics of Bridge Waterways" (Momentum & Energy Methods).