×
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.

# Reduce Negative Coefficient 10%

## Reduce Negative Coefficient 10%

(OP)
If a negative coefficient is reduced 10%, does the number become larger or smaller. For example, if -1.0 is reduced 10%, does it become -1.1 or -0.9? In other words, is the magnitude reduced or numeric value reduced?

The context is a footnote in ASCE 7-10 Minimum Design Loads for Buildings and Other Structures figure 30.4-1 (or ASCE 7-05 figure 6-11A) that states: "Values of GCp for walls shall be reduced by 10% when θ ≤ 10°"
Figure 30.4-1 is used to calculate wind loads and the coefficient can be positive or negative.

### RE: Reduce Negative Coefficient 10%

-1.0*0.9=-0.9 as far as I know.

NX 7.5.5.4 with Teamcenter 8 on win7 64
Intel Xeon @3.2GHz
8GB RAM

### RE: Reduce Negative Coefficient 10%

Your post contains both the question: “is the magnitude reduced or numeric value reduced?”
And the answer: “"Values of GCp for walls shall be reduced by 10%”

### RE: Reduce Negative Coefficient 10%

reduced means the number gets lower. After all zero is arbitrary.

f-d

¡papá gordo ain’t no madre flaca!

### RE: Reduce Negative Coefficient 10%

Reduced (probably) means subtract.

How much to subtract? 10%

10% --> 0.1

-1.0*0.1=-0.1

-1.0 reduced by -0.1

-1.0 - (-0.1) = -0.9

Having gone through that exercise, codes need to be clear, precise and unambiguous. This language is not.

### RE: Reduce Negative Coefficient 10%

#### Quote:

reduced means the number gets lower. After all zero is arbitrary.

f-d

Technically, 'reduced' means 'made smaller', not lower.

A large negative number is still large.
A small number is closer to 0, either positive or negative.

That said, in the original, the coefficient itself is not negative, and the language refers to making the coefficient smaller.

### RE: Reduce Negative Coefficient 10%

(OP)
Thank you for the responses. The wording could be more precise (less ambiguous). I like Fattdad and Mint Juleps reasoning; but which one is right? I checked at work today, and the same language is in the 1998 and 2002 editions of the code. I plan to contact the ASCE 7 wind committee and propose changes to this language.

### RE: Reduce Negative Coefficient 10%

i guess the word "reduce" is open to interpretation ...
1) does it refer to the magnitude ? (ie get closer to zero)
2) does it refer the numerical value (so a -ve number would get more negative)
if you're dealing with a code, then i'd ask around for the generally accepted interpretation.

Quando Omni Flunkus Moritati

### RE: Reduce Negative Coefficient 10%

I've always taken "reduced" to mean "closer to zero", but now I'm wondering if that is correct.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

### RE: Reduce Negative Coefficient 10%

There is a big difference between "If a negative coefficient is reduced 10%" and "If a negative coefficient is reduced by 10%".
If a negative coefficient is reduced 10% ==> NC - 10%
If a negative coefficient is reduced by 10% ==> NC * 0.9

Good Luck
--------------
As a circle of light increases so does the circumference of darkness around it. - Albert Einstein

### RE: Reduce Negative Coefficient 10%

#### Quote (CajunCentruion)

There is a big difference between "If a negative coefficient is reduced 10%" and "If a negative coefficient is reduced by 10%".
If a negative coefficient is reduced 10% ==> NC - 10%
If a negative coefficient is reduced by 10% ==> NC * 0.9

No there isn't.

If a negative coefficient is reduced 10% ==> NC - 10% Expressed properly is NC - (NC * 0.1) --> NC * (1-0.1) --> NC * 0.9

### RE: Reduce Negative Coefficient 10%

If negative coefficient is "increased" by 10%, it will be (NC + 10%), in other words NC x 1.1.

So if negative coefficient is "reduced" by 10%, it should be NC x 0.9.

### RE: Reduce Negative Coefficient 10%

If you turn the air conditioner "up" are you making the temperature in the room colder or warmer?

f-d

¡papá gordo ain’t no madre flaca!

### RE: Reduce Negative Coefficient 10%

Not too many answers from civils or structurals here. Maybe you've got the wrong forum. I'd ask those who use the code in question. I'd also ask which answer yields the most conservative and/or sensible result. And to fattdad, my answer is warmer. My wife of course disagrees.

#### 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.

#### Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a partâ€™s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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!