×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Wind force coeff Cf when h/d > 25 for cylindrical structures?3

 Forum Search FAQs Links MVPs

## Wind force coeff Cf when h/d > 25 for cylindrical structures?

(OP)
Pals

I have a copy of ASCE 7-88

for vertical cylindrical shapes(chimneys tanks and similar) wind force coefficients depend on ration h/d, d.root(q) and surface roughness. Values given in ASCE 7-88 table 12 stop when h/d = 25.

ASCE puts a note that you can interpolate for values of h/d not shown in the table.

This statement says nothing about the limits of h/d.

What happens when h/d > 25 (The cylinder is very slender but so many cylinders we know have h/d > 25)

respects

IJR

### RE: Wind force coeff Cf when h/d > 25 for cylindrical structures?

The h/d>25 is the same value as h/d=25. End & edge effects are minimal for long pipes and similar shapes.

### RE: Wind force coeff Cf when h/d > 25 for cylindrical structures?

(OP)
Thank you Civilperson

Do you know anywhere in the code where I can find a reference to your comment?

### RE: Wind force coeff Cf when h/d > 25 for cylindrical structures?

The only reference I have is for h/d = 25... the general data comes from Report Nr 160 from Swiss Assoc of Eng and Arch (1956).  The data is in Supplement 3 to the NBC of Canada 1960.  It also notes smoothe and rough surfaces.  For taller structures, I'd use the increased forces for height.  The loading information has the pressure located at increments of 15degrees.  I don't know what ASCE-7 has.

Dik

### RE: Wind force coeff Cf when h/d > 25 for cylindrical structures?

ASCE7-05 has the same table and has not referenced anything else. It has to be assumed that the values in the table are for h/D less than or equal to 1 and greater than or equal to 25.

Larry

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

#### Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!