Transcript Document

StormCAD Basics
Mal Sharkey
Be Conf. 2007
Our users design, build, and operate the
world’s infrastructure – improving quality
of life for everyone.
We provide software to help them do it
better and faster.
Part 1
• Intro to StormCAD
What is a Storm Sewer System?
A storm sewer system is composed of surface components
(e.g., gutters and inlets) and subsurface components (e.g.,
pipes, manholes, inlet boxes)
Storm Sewer Design
• Storm sewer design and analysis consists of 2 basic
parts:
− Surface flow calculations
− Subsurface flow calculations
• Surface flow calcs evaluate the capacity of gutters
(i.e., gutter spread and depth) and inlets (for inlets on
grade, part of the flow, called “bypass flow,” will not be
picked up and will continue down to the next inlet).
• Subsurface flow calcs evaluate the capacity of the
subsurface pipes to prevent flooding. Storm sewer
pipes should always point downhill, and the systems
are branched (i.e., typically, there should not be loops).
Storm Sewer Design
52
Subsurface (pipe) layout
52
0
0
I- PL3
I- 4L
P -4
P -P L2
L
0
2
520
R
2L
I- 3R
J- 2
51
P -2
1
R
P -C
I- 1L
J- 3
L
P-
P -C
I- 4R
P -3
I- PL2
I- PL1
3
R
1
-P L
P -3
P
J- 4
P -4
52
P -C
I- 3L
P -1
I- 2R
P -O
1
5
P -1
L
J- 5
51
J- 1
0
R
P- O2
I- 1R
Outlet
Haestad Methods Inc.
SAMPLE 4
J an 20 03
Parking Lot and Roadway
Stor m S ew er Collection System
S am p le 4
S he et 1 / 1
Surface (gutter)
connectivity
Plan View
Profile: I-1 l to O utlet
Sc e n a r i o : 1 0 0 - y e a r S to rm
Profile View
Label: I-1 L
R im : 518.2 0 ft
Su m p: 513 .53 ft
Label: J- 1
R im : 518.4 0 ft
Su m p: 513 .51 ft
Label: J- 2
Label: I-2 R
R im : 516.9 0 ft R im : 516.8 0 ft
Su m p: 511 .15 ft Su m p: 510 .80 ft
Label: J- 5
R im : 518.2 0 ft
Su m p: 510 .72 ft
520.00
Label: Ou tlet
R im : 510.6 0 ft
Su m p: 508 .60 ft
Label: P- 1L
U p. Inv ert : 513.53 ft
D n. Inv ert : 513.51 ft
L: 13.00 ft
Si ze : 8 inc h
S: 0.0 01500 ft/ ft
0+00
515.00
El eva tion (ft)
510.00
1+00
Label: P- C 1
U p. Inv ert : 513.51 ft
D n. Inv ert : 511.15 ft
L: 105.00 ft
Si ze : 8 inc h
S: 0.0 22513 ft/ ft
Label: P- 2R
U p. Inv ert : 511.15 ft
D n. Inv ert : 510.80 ft
L: 13.00 ft
Si ze : 15 in ch
S: 0.0 26923 ft/ ft
2+00
Label: P- O 1
U p. Inv ert : 510.80 ft
D n. Inv ert : 510.72 ft
L: 55.50 ft
Si ze : 24 in ch
S: 0.0 01500 ft/ ft
3+00
Station ( ft)
Label: P- O 2
U p. Inv ert : 510.72 ft
D n. Inv ert : 508.60 ft
L: 236.50 ft
Si ze : 24 in ch
S: 0.0 08950 ft/ ft
4+00
505.00
5+00
Gutters
• Flow typically travels to
storm sewer inlets
though gutters
• The engineer is
interested in the width
and depth of the gutter
flow, and has to make
sure that neither is
excessive.
• Gutter flow is analyzed
using a form of
Manning’s equation
Inlets
• Three common inlet types are grate inlets, curb inlets, and
combination inlets.
• Inlets may be located on a continuous grade or in a sag location
• Inlets on grade do not intercept 100% of the flow that comes to
them—some of the flow bypasses and goes to the next inlet
downgrade
• HEC-22 calculation methods are used to determine gutter spread
and depth and inlet capacity
Storm Sewer Profile
StormCAD
Storm sewer design & analysis
with inlet modeling
StormCAD
Applies to:
− Commercial site design
− Land development
− Roadway drainage design
− Planning, mapping, and inventories for
larger areas (e.g., municipality)
StormCAD
Capabilities
− Uses rational method hydrology
− Performs gradually varied flow profile
analysis
− Incorporates HEC-22 methods for inlet and
gutter capacity calcs, including gutter
spread and bypass flow calcs
− Performs automated pipe & inlet design
− Includes GIS and database connections
− Generates profile plots and tabular reports
− Includes MicroStation & AutoCAD
integration options
− Includes Scenario Management
User Interface
Compute Button
Zoom Tools
Tabular Reports
Graphical Tools
Scenario
Element
Symbology
Layout
Tools
Background
Layers
Drawing
Area
Basic Data Entry
Layout Toolbar
Pipe Tool
Right-click
menu to change
element type
FlexTables
•
•
•
•
Sort
Filter
Global Edit
Customize
Property Grid
ModelBuilder: Using External Data
Convert CAD
lines, polylines,
and blocks
Connect to
any database
& keep it in
sync with
your model
Connect to
shapefiles
Part 2
• Getting familiar with StormCAD
A little more theory…
Open Channel Flow
•Open channel flow is flow that
has a free water surface open to
the atmosphere.
•It occurs in natural rivers and
streams, manmade ditches and
channels, gutters, and gravityflow pipes.
Gutter
Conservation of Energy
•In open channel flow, the pressure head term (p/γ) is
replaced by the vertical flow depth y
•The energy equation between sections 1 and 2 for the
2
2
channel shown is written as: y  V1  z  y  V2  z  h
1
2g
1
2
2g
2
L
Open Channel Flow Definitions
Normal Flow
− If a channel shape remains constant for a long enough
distance, the flow will reach a constant “normal depth.”
Varied Flow
− Flow depth typically varies along the length of a channel due
to factors like changing channel shape or flow depths other
than normal depth on the upstream or downstream end.
− Varied flow can change gradually along a channel (“gradually
varied flow” or GVF) or rapidly (in the case of a hydraulic
jump).
Supercritical vs. Subcritical Flow
− These are the 2 basic flow types possible for flow in an open
channel.
− Supercritical flow is shallow, high-velocity flow
− Subcritical flow is deeper, slower-velocity flow
− Flow can transition from subcritical to supercritical flow, or
vice versa
− Between supercritical flow and subcritical flow is the “critical
depth.” This value can be determined for any channel and
used to classify the flow type. Sometimes, it is also used as
a starting point (boundary condition) in GVF calculations
Open Channel Flow Types
Normal Flow
Transition from Subcritical to
Supercritical flow
Transition from Supercritical to
Subcritical Flow (Hydraulic Jump)
Graphic Output
Annotation
Color Coding
Profiles
Data Management
Queries
Network Navigator
Selection
Sets
Part 3
• Analysis in StormCAD
Rational Method
To compute a peak flow rate from a watershed, a method such
as the Rational Method can be used:
Q=c×i×A
− Q is the peak discharge from the drainage area
− c is the “runoff coefficient” (the fraction of rainfall that is converted to
runoff)
− i is the intensity of the rainfall for a design storm event having a duration
equal to the drainage area “time of concentration”. This can be obtained
using intensity-duration-frequency curves for the locale (see below).
− A is the area
Inlet Calculations
Perform inlet capture & bypass
calcs using HEC-22 methods
Store inlet properties in
an engineering library
Set up gutter
networks
Multiple Scenarios
Create alternative input
data sets with
Alternative Manager
Model a variety of
situations using Scenario
Manager
Active Topology
Before site is developed
(proposed elements are
inactive)
After site is
developed
Viewing Output
FlexTables
Reports
Property
Grid
MicroStation & AutoCAD Integration
StormCAD can run inside MicroStation or AutoCAD
StormCAD Basics
Mal Sharkey