Discussion: View Thread

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

A new scour analysis and HEC-18 publication is in editing stages and expected out soon (probably within a year). Just in case this helps inform your decision.

------------------------------
Joanna Curran A.M.ASCE
Dr.
SEATTLE WA
------------------------------

Original Message:
Sent: 11-28-2017 21:36
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

​Joanna:  Thanks for the information on the new upcoming publication.  I'll look out for it.   David

------------------------------
David Williams Ph.D., P.E., D.WRE, HG, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

Original Message:
Sent: 11-30-2017 02:06
From: Joanna Curran
Subject: Interest in ASCE webinar short course - Bridge scour analysis

A new scour analysis and HEC-18 publication is in editing stages and expected out soon (probably within a year). Just in case this helps inform your decision.

------------------------------
Joanna Curran A.M.ASCE
Dr.
SEATTLE WA

Original Message:
Sent: 11-28-2017 21:36
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

Dr. Curran - Thank you for sharing. I believe the NCHRP Local Abutment Scour method will be tweaked with regards to additional guidance on when to use the clear or live bed scour condition. Do you know what NCHRP report will be incorporated into the new edition?

------------------------------
Jeffrey De Graff P.E., L.S.I.T., M.ASCE
Engineer
Hoyle Tanner and Associates
Burlington VT
------------------------------

Original Message:
Sent: 11-30-2017 02:06
From: Joanna Curran
Subject: Interest in ASCE webinar short course - Bridge scour analysis

A new scour analysis and HEC-18 publication is in editing stages and expected out soon (probably within a year). Just in case this helps inform your decision.

------------------------------
Joanna Curran A.M.ASCE
Dr.
SEATTLE WA

Original Message:
Sent: 11-28-2017 21:36
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

There is work on-going now from NCHRP RFP 24-47 on clear water and live bed contraction scour in cohesives and fines. An RFP is about to be issued concerning the development of scour equations for gravel bed rivers. Please watch for it if anyone is interested in pursuing the question.
In discussions with the people at federal highways, it sounded like updates to HEC-18 are being edited, so coming out within the year, and they will be planning on incorporating further updates from these projects. No firm date for the release though.

------------------------------
Dr. Joanna Curran A.M.ASCE
SEATTLE WA
------------------------------

Original Message:
Sent: 12-01-2017 06:14
From: Jeffrey De Graff
Subject: Interest in ASCE webinar short course - Bridge scour analysis

Dr. Curran - Thank you for sharing. I believe the NCHRP Local Abutment Scour method will be tweaked with regards to additional guidance on when to use the clear or live bed scour condition. Do you know what NCHRP report will be incorporated into the new edition?

------------------------------
Jeffrey De Graff P.E., L.S.I.T., M.ASCE
Engineer
Hoyle Tanner and Associates
Burlington VT

Original Message:
Sent: 11-30-2017 02:06
From: Joanna Curran
Subject: Interest in ASCE webinar short course - Bridge scour analysis

A new scour analysis and HEC-18 publication is in editing stages and expected out soon (probably within a year). Just in case this helps inform your decision.

------------------------------
Joanna Curran A.M.ASCE
Dr.
SEATTLE WA

Original Message:
Sent: 11-28-2017 21:36
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

Thanks JoAnna for the info on the manual.  I'll look for it!

Regards
Drew

------------------------------
Drew Baird Ph.D., P.E., D.WRE, M.ASCE
Senior Hyd Eng
US Bureau of Reclamation (86-68540)
Denver CO
------------------------------

Original Message:
Sent: 11-30-2017 02:06
From: Joanna Curran
Subject: Interest in ASCE webinar short course - Bridge scour analysis

A new scour analysis and HEC-18 publication is in editing stages and expected out soon (probably within a year). Just in case this helps inform your decision.

------------------------------
Joanna Curran A.M.ASCE
Dr.
SEATTLE WA

Original Message:
Sent: 11-28-2017 21:36
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

​Drew:

Since I am located so close to your office in Lakewood, I am willing to do an in-house presentation (when finished creating the material) on this for the BOR is you are interested.. As always to my friends at the BOR, this would be for free.

David

------------------------------
David Williams Ph.D., P.E., D.WRE, HG, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

Original Message:
Sent: 12-05-2017 16:46
From: Drew Baird
Subject: Interest in ASCE webinar short course - Bridge scour analysis

Thanks JoAnna for the info on the manual.  I'll look for it!

Regards
Drew

------------------------------
Drew Baird Ph.D., P.E., D.WRE, M.ASCE
Senior Hyd Eng
US Bureau of Reclamation (86-68540)
Denver CO

Original Message:
Sent: 11-30-2017 02:06
From: Joanna Curran
Subject: Interest in ASCE webinar short course - Bridge scour analysis

A new scour analysis and HEC-18 publication is in editing stages and expected out soon (probably within a year). Just in case this helps inform your decision.

------------------------------
Joanna Curran A.M.ASCE
Dr.
SEATTLE WA

Original Message:
Sent: 11-28-2017 21:36
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

I thought of another one.  If a pier sits on a pile cap, the predicted pier scour should be examined to see if exposes the cap. If it does, the pier scour computation should be redone using the projected width and appropriate "nose" shape of the cap.

------------------------------
David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

------------------------------
David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
------------------------------

​I would have an interest in attending such a webinar when available.  Please keep me apprised.
Thanks,
Glenn Eby

------------------------------
Glenn Eby P.E., M.ASCE
Senior Project Manager
JHA Companies
Montrose PA
------------------------------

Original Message:
Sent: 11-28-2017 15:24
From: David Williams
Subject: Interest in ASCE webinar short course - Bridge scour analysis

​hi all:

I do several ASCE webinars and am thinking of adding another one but want to gauge the interest.

I have seen many mis-applications of HEC-RAS when performing bridge scour studies.  I have compiled 6 so far of the most common mistakes (I will use a total of 8) that I have encountered and would like to present then in a 90 minute webinar that ASCE could market and generate revenues.  I am open to suggestions for more problems that you may have seen and am willing to swap out my proposed problems if deemed that the suggested one are more important.

The topics are:

1. Scour depth for piers should be using hydraulics at the thalweg and applied to all piers within the area of anticipated lateral movement of the main channel.  If you assume that the main channel may move laterally, the worst case is if the thalweg moves to each of the piers - therefore the hydraulics at the thalweg (and resulting scour) should be applied to all piers and the scour depth should be applied to the thalweg elevation to determine the scour ELEVATION at each pier.  The way HEC-RAS displays pier scour is not appropriate.
2. Pier groups that are close together (within 5 pier diameters, per HEC-18) must be model as one pier using the group projected width and if skewed, take into consideration as a group and input to the skew variable in the scour menu.
3. If debris is modeled on the piers for hydraulic considerations, must also add to the pier width for pier scour.
4. Froehlich's pier/abutment scour already has safety factor (essentially 100%) in it so do not have to add a safety factor to the scour results.
5. Don't double count pier skew.  For elongated piers, enter width of pier (not projected width) and add the skew to the scour input.  Enter the projected width for the bridge pier width for the hydraulics.  If the situation is as per item 2 above, use the proper projected width of the pier group for the pier width in the hydraulics.
6. Double check if approach and exit cross sections that are automatically assigned for bridge modeling are at the proper location.  The proper ones to assign are cross sections 1 and 4 of the traditional cross sections used in HEC-RAS bridge modeling.  If there are cross sections between 1 and 2 and between 3 and 4, HEC-RAS assigns the closest downstream cross sections from 2 and closest upstream cross sections from 3.  This affects the contraction and abutment scour computations.
7. Suggestions?
8. Suggestions?

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David Williams Ph.D., P.E., PH, D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
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Original Message------

​I would have an interest in attending such a webinar when available.  Please keep me apprised.
Thanks,
Glenn Eby

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Glenn Eby P.E., M.ASCE
Senior Project Manager
JHA Companies
Montrose PA
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​Sanmy:  I have done short courses in sediment transport but they were on-site seminars, not webinars.  David

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David Williams Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
David T. Williams and Assoc.
Commerce City CO
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