Hecras exercise 1 and 2
Budget: €30 – €250 EUR
HEC-RAS Simple Channel Exercise (Steady State)
Exercise 2: – 5 %
Due Date: December
Use HEC-RAS instruction manual follow the instructions on the HEC RAS Channel Exercise (steady state) document for entering and executing the programme.
A bridge deck with prescribed deck dimensions and without piers is placed in the path of the flow. The resulting flow profiles are shown and compared to the existing profiles which pertained before the bridge was placed. The student must then revise the bridge dimensions (deck thickness / lower chord elevation) so that the bridge is not overtopped by the two smaller flows (out of three)
Detailed Brief
Start off by opening the last computed file saved in HEC RAS Practical 1, i.e. the calibrated model.
Using the document*, above, enter the bridge carefully as instructed at a newly created station and enter the bridge dimensions given. The flow profiles are PF1, PF2 and PF3 correspond to flows of 10, 30 and 50 m3/s as before. Save the geometry file and plan file and compute for steady flow analysis. The following data must be presented in your report:
1) For the given bridge and flows (describe them first for clarity):
a) Cross-sectional flow profiles for the three flows at the bridge
b) Longitudinal flow profiles for the three flows with the bridge
c) Comparative longitudinal flow profiles between the bridge scenario and the original channel
d) The table which shows the output data including how the flow is split between weir and orifice flow
e) Show separately the weir flow and the orifice flow for clarity
2) Make your own changes to the bridge geometry to allow 10 and 30 m3/s to pass without causing weir flow over the deck while retaining a sensible deck depth for structural reasons. In the report for the revised bridge include:
a) A description of the changes
b) The new longitudinal flow profiles for the three flows with the bridge to prove no overtopping for 10 and 30 m3/s
c) The table which shows the output data and extract from the table the weir flow and the orifice flow and highlight them separately
d) State why the 50 m3/s flow might be allowed flow over the bridge deck?
Exercise 2: – 5 %
Due Date: December
Use HEC-RAS instruction manual follow the instructions on the HEC RAS Channel Exercise (steady state) document for entering and executing the programme.
A bridge deck with prescribed deck dimensions and without piers is placed in the path of the flow. The resulting flow profiles are shown and compared to the existing profiles which pertained before the bridge was placed. The student must then revise the bridge dimensions (deck thickness / lower chord elevation) so that the bridge is not overtopped by the two smaller flows (out of three)
Detailed Brief
Start off by opening the last computed file saved in HEC RAS Practical 1, i.e. the calibrated model.
Using the document*, above, enter the bridge carefully as instructed at a newly created station and enter the bridge dimensions given. The flow profiles are PF1, PF2 and PF3 correspond to flows of 10, 30 and 50 m3/s as before. Save the geometry file and plan file and compute for steady flow analysis. The following data must be presented in your report:
1) For the given bridge and flows (describe them first for clarity):
a) Cross-sectional flow profiles for the three flows at the bridge
b) Longitudinal flow profiles for the three flows with the bridge
c) Comparative longitudinal flow profiles between the bridge scenario and the original channel
d) The table which shows the output data including how the flow is split between weir and orifice flow
e) Show separately the weir flow and the orifice flow for clarity
2) Make your own changes to the bridge geometry to allow 10 and 30 m3/s to pass without causing weir flow over the deck while retaining a sensible deck depth for structural reasons. In the report for the revised bridge include:
a) A description of the changes
b) The new longitudinal flow profiles for the three flows with the bridge to prove no overtopping for 10 and 30 m3/s
c) The table which shows the output data and extract from the table the weir flow and the orifice flow and highlight them separately
d) State why the 50 m3/s flow might be allowed flow over the bridge deck?