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Multi-Lat 2003 now available
- To: <seaint(--nospam--at)seaint.org>, <residential(--nospam--at)structuralist.net>, <light_framing(--nospam--at)structuralist.net>
- Subject: Multi-Lat 2003 now available
- From: "Dennis Wish" <dennis.wish(--nospam--at)verizon.net>
- Date: Thu, 25 Sep 2003 20:11:25 -0700
I am pleased to
announce an update to the Multi-Lat spreadsheet that David Merrick and I wrote
upon adoption of the 97 UBC. I have temporarily removed the rigid diaphragm
analysis based on a study that I performed which indicated that most engineers
were using increased base shears rather than to design residential structures
comparing or including rigid and flexible analysis. The outcome was considerably
more conservative than using a simplified static principle.
I will be adding the
rigid analysis back in as soon as I can integrate it better with the flexible
analysis. I feel it is more appropriate for commercial and industrial buildings
that have large openings which induce greater horizontal shears by rotation that
need to be resisted or which can be determined to be included adequately in the
capacity of the shearwalls or other shear resisting elements.
This new spreadsheet
has some improvements for walls that don't stack as well as for cantilevered
diaphragms. The spreadsheet performs a flexible diaphragm analysis for up to
five blocks and each block up to three stories in height. It compares wind and
seismic (based on the type of resisting system's "R" value) and analyzes the
block for the worst case scenario.
I am also in the
process of writing an online tutorial located on the Structuralist.Net that will
help you use the spreadsheet. The only changes you need to know how to operate
are the printing functions in Excel so that you can adjust the print area for a
one, two or three story block.
For those familiar
with the original spreadsheet, there were problems based on lateral distribution
from level to level when walls did not stack. This has been repaired and there
are some very creative ways to use the spreadsheet - thus the reason to create
an online tutorial.
Until the tutorial
is complete, I am taking any and all questions on how to use the spreadsheet and
creative uses for blocks that are not orthogonal (skewed shear
To download the
2. Click on the
button labeled "Structuralist BBS" on the left side of the
3. This will take
you to our YABBSE Bulletin Board, scroll down to "User Software Forum" and click
on the this title in blue.
4. Click on
Multi-Lat 2003 Now Available for Download to open the message posted
5. Read the
information provided and at the bottom of this message is a bold blue link that
says "Click here to download the latest version of Multi-Lat
6. Either click on
this link, or right click on the link and choose "Save Target As...". You may
rename the file or simply choose a location such as your desktop to download
If and when you need
help, please post your questions on the Software discussion forum by clicking on
"New Topic" and entering your question or comments. I will be notified when you
post. You may need not be registered with the site to post a message, but you
will need to leave a valid e-mail address and name to post. It is more
convenient to register with the BBS. This prevents any spammers and provides you
with a great deal of other useful features. These advantages are covered in the
BBS home page (My Community) General Category - Announcements: "Registration
Privileges". Please feel to leave your questions or comments
1. Diaphragms in
each block do not have to be at the same elevation as adjacent
2. Blocks can be
skewed (non-orthogonal) based on the assumption that the direction of the force
is normal to the block rather than the entire structure (conservative).
3. Diaphragms can
include cantilevers by arbitrarily inputting 2L for the diaphragm span to the
first line of resisting shear. The spreadsheet assumes L/2 as the reaction for
4. For multi-story
shear distribution ALL LINES OF SHEAR MUST BE DEFINED AS IF THE BLOCK WERE
TRANSPARENT. IN OTHER WORDS, EACH GRID LINE MUST BE DEFINED IN EACH LEVEL SO
THAT LINES OF RESISTANCE IN EACH LEVEL CAN BE TURNED ON AND OFF AND DISTRIBUTION
IS PROPERLY TRANSFERED FROM LEVEL TO LEVEL.
5. The user has the
option of changing the method of resistance for each block and in each direction
(plywood shear walls, moment frame, proprietary shear elements, cantilevered
columns, masonry or concrete walls etc.).
6. Shear is not
distributed to flexible walls in the same line of resistance based on wall
rigidity. This is not allowed in the 97 UBC and until it is modified, the user
can only distribute shear per linear foot of wall.
7. Wind and Seismic
forces are compared in each line of resistance and the worst case load is used.
Diaphragm deflection is checked, although the aspect ratio of the diaphragm must
encroach upon 4:1 before the diaphragm will be considered flexible.
8. The user may
input up to five wall segments in each line of shear. Each block allows for 10
lines of resistance with five walls each for three story or a maximum of 150
shearwall sections that may be used in each block.
I've used the
spreadsheet to design irregular shaped structures and found that it can be a
very creative and useful tool. The benefits are not immediately apparent until
you learn how to link blocks together to resolve the shears in each line of
resistance. You may have a block that does not contain a diaphragm at a level
adjacent to one or two other blocks (such as an atrium). You can resolve this in
I am currently
creating a summary shearwall schedule that can be printed and placed on your
drawing to identify all shear walls by grid line and wall
Enjoy the software
and please write to let me know of any problems as well as all creative ways you
have used the spreadsheet to resolve multi-story lateral distribution in
irregular shaped structures.
Dennis S. Wish,