ASCE702W.xls
(5/19)
Description
"ASCE702W" --- ASCE 7-02 CODE WIND ANALYSIS PROGRAM
"ASCE702W" is a spreadsheet program written in MS-Excel for the purpose of wind loading analysis for buildings and structures per the ASCE 7-02 Code. Specifically, wind pressure coefficients and related and required parameters are selected or calculated in order to compute the net design wind pressures.
This program is a workbook consisting of eight (8) worksheets, described as follows:
Worksheet Name
Doc - This documentation sheet
Simplified - Analysis using simplified method for low-rise buildings with h <= 60’
MWFRS (Low-Rise) - Main Wind-Force Resisting System for low-rise buildings with h <= 60’
MWFRS (Any Ht.) - Main Wind-Force Resisting System for buildings of any height
Wall C&C - Analysis of wall Components and Cladding
Roof C&C - Analysis of roof Components and Cladding
Stacks & Tanks - Analysis of cantilevered chimneys, stacks, and vertical tanks
Wind Map - Basic wind speed map (Figure 6-1 of ASCE 7-02 Code)
Program Assumptions and Limitations:
1. This program assumes only enclosed or partially enclosed buildings. Open buildings are NOT considered.
2. Worksheet for Simplified analysis is applicable for low-rise buildings meeting the criteria of Section 6.4.1.
3. In the worksheet for Simplified analysis, the design MWFRS wind load is calculated for each direction. The design MWFRS load is assumed to be the total wind load on either the width or the length of the building respectively.
4. Worksheet for MWFRS (Low-Rise) is applicable for low-rise buildings as defined in Section 6.2.
5. Worksheets for MWFRS (Any Ht.), Wall C&C, and Roof C&C are applicable for buildings with mean roof heights of up to 500 feet.
6. In worksheets for MWFRS (Any Ht.), Wall C&C, and Roof C&C the user may opt to utilize user designated "steps" in height, "z", in determining the wind pressure distribution.
7. Worksheet for Stacks & Tanks is applicable for cantilevered structures up to 600 feet tall.
8. Worksheets for Wall C&C and Roof C&C are applicable for flat roof buildings, gable roof buildings with roof angles <= 45 degrees, and monoslope roof buildings with roof angles <= 3 degrees.
9. Worksheets for MWFRS (Any Ht.) and for Stacks & Tanks can handle “rigid” as well as “flexible” buildings and structures. For “rigid” buildings or structures, this program uses the smaller value of either 0.85 or the calculated value from Section 6.5.8.1 of the Code for the gust effect factor, 'G'. For “flexible” buildings or structures, this program calculates the gust effect factor, ‘Gf’, per Section 6.5.8 of the Code based on the assumed formula for the fundamental period of vibration from Section 9.5.5.3 of the Code.
10. This program uses the equations listed in the reference, “Guide to the Use of the Wind Load Provisions of ASCE 7-02” for determining the external wind pressure coefficients, ‘GCp’, used in the Wall C&C and Roof C&C worksheets.
11. This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc. (Note: presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell. Merely move the mouse pointer to the desired cell to view the contents of that particular "comment box".)
Useful Web Resource
I was given a couple of websites which you might find convenient for determining the basic wind speed and ground snow load
for any location in the continental United States per the ASCE/SEI 7-05 Code, so I thought I'd pass them along.
The website links are as follows:
Calculation Preview
(5/19)
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I was given a couple of websites which you might find convenient for determining the basic wind speed and ground snow load
for any location in the continental United States per the ASCE/SEI 7-05 Code, so I thought I'd pass them along.
The website links are as follows:
http://www.windspeedbyzip.com/
http://www.groundsnowbyzip.com/
You must register to make use of either website, but you only have to register at one, not both of the websites.
Once you register at one of them, you will automatically have access to information from the other one.
The two websites allow you to input either the street/city/state address or just the zip code.
The resulting location latitude and longitude are given. Regular (street), satellite, and hybrid maps are available as well.
It is referring to the main wind force resisting system analysis.
My questions are:
1.) The spreadsheet indicates in the notes that if the wind pressures for Zones "B" and "D" < 0, assume = 0. Where exactly is this provision coming from (ASCE7-05...)? I have seen designers instead of using the negative values they simply just switch the sign to + and call it conservative. Does the ASCE7-05 Address this issue (where)? And if it is correct to assume they are 0 then why have does the ASCE7-05 even have the negative values showing, wouldn't it make sense to set them to zero in the first place.
I know that the negative values are stating that they are coming out of plane therefore create a circular motion and a possible moment about the roof system. But when doing the analysis calculations I have never subtracted the negative B and D regions from the A and C when finding the shear reactions.
2.) This question is referring to another code provision. It is specifically ASCE7-05 6.4.2.1.1 about minimum pressures. What is the take on this? I see it two different ways:
a. That you must have 10 psf minimum on all zones A,B,C and D. Implying that if B and D were negative or < than 10 the would then become positive 10.??
b. The minimum design pressures on any structure have to exceed a minimum of 10 psf for all zones based on the area Af? And if the pressures are less than that when analyzed then 10 psf's have to be used for all the zones.
Thats it for now, thanks for your guys is time
First of all, you are obviously referring to the ASCE705W.xls workbook, not the ASCE702W.xls workbook by the version number that you mentioned. So the subject of this post should actually refer to the ASCE 7-05 version.
Yes, in the "Stacks & Tanks" worksheet, I agree with you that there is an error and that the calculation for the wind force coefficient, Cf, off of the main calculation page to the right needs some work. However, remember that the value of Cf is actually to be manually input by the user in cell B20. So the user can still be responsible for inputting the correct value of Cf until I release the corrected version.
There was a "typo" error in cell AC17, in that the last 3 should have been a 1 because the the type of round surface category 3 (for D'/D>=0.08) had already been defined earlier in that statement. Also in cell AC17 as well as cell AC20, I did not have the logic included to account for round vessels where D*SQRT(qz)<=2.5.
I believe that I have made the necessary corrections, will back check myself, and release an updated version very soon.
Thanks for bringing this to my attention.
Alex
I found an error under the Stacks and Tanks tab. The calculation of Cf for circular tanks of various roughness needs some work. The label for the roughness looks like it works. However, the value for the roughness does not correspond to the D'/D and causes the wrong value to be interpolated.
I see. The version I have is version 1.4. I missed the fact that this is an outdated version.
regards,
chichuck.
You are correct in the formula as you have shown it in your post. However, the ONLY error that I see in version 1.8 of that worksheet which is currently on the calculation repository is in the formula that is displayed in the comment box. The actual calculation formula as well as the text displayed version of the formula look to be correct to me (just as you have shown it).
I have been working on a workbook for wind analysis per the ASCE 7-05 Code and I already picked up the error in the comment box. I will issue version 1.9 to this workbook soon, about the same time that I issue the new "ASCE705W.xls" workbook.
Alex
However, I think I've found an error in the stacks & tanks page. It seems from posts below that its appropriate to post it here. So here goes:
on the stacks and tanks tab, in cel B98 and the accompanying C98, there is a misplaced ) that results in an incorrect value for flexible structure gust factor.
the formula in B98 matches the description in C98.
as is, cell C98 shows
'= 0.925*(1+1.7*Iz(bar)*(gq^2*Q^2+gr^2*R^2)[color=#FF0000])[/color]^(1/2)/(1+1.7*gv*Iz(bar)) , Eq. 6-8
with my proposed correction, cell C98 would read
'= 0.925*(1+1.7*Iz(bar)*(gq^2*Q^2+gr^2*R^2)^(1/2)[color=#FF0000])[/color]/(1+1.7*gv*Iz(bar)) , Eq. 6-8 the red parenthesis is the one I've corrected
Check Eq. 6-8 in the code and note what is under the radical, I think my correction makes the formula right. Cell B98 formula needs to be corrected to match.
I don't know if this error also occurs on other pages.
Still, an excellent worksheet.
regards,
chichuck
Typically in industrial work we don't encounter such steep roof angles.
However, one of the guys who was doing some work outside of the industrial market sector brought this to my attention. In a sense the program wasn't really wrong, but merely overly conservative by not making use of permitted interpolation.
This has now been corrected.
I have started on a workbook for wind loading analysis per the ASCE 7-05 Code. I hope to have it completed in the near future.
One of the guys pointed out a typo error to me in the "ASCE702W.xls"
spreadsheet workbook. In the "MWFRS (Any Ht.)" worksheet at the bottom of the 4th page at Note #3, it should read "PLx, PLy = Leeward face pressure.....". It was inadvertently shown as "PLx, PLy = Windward face pressure.....". The diagrams shown above the notes would have clarified this. This has now been corrected.
I also corrected a couple of page breaks that were not coming out in the correct positions. I usually place a border around each of the pages of a particular worksheet, so it is easy to adjust the page breaks to line up with these borders if necessary, in the event that they are not coming out right with your particular printer/driver.
Alex Tomanovich, P.E.
Senior Structural Engineer
This workbook is now version 2.1.