ERRATA
November 8, 1999 – Version 1.0 build 110899
1.       
This version corrects a problem in the evaluation of
near source factor Na. A patch was applied to the
formula for that searches 2D table (with rows and column headings) using
Excel’s Index and Match functions.
2.       
The original version was shipped with the recalculation
option set to manual. This option has been switched to automatic in this
version.
 
October 17, 1999
Re: Final Final Released Version of 1997 UBC Lateral Design
Spreadsheet
It seems I was a bit hasty in sending out this spreadsheet
yesterday as I must have been blind or overstressed by work to miss the glaring
problem that was not resolved. I apologize for this and urge you all to delete
all prior versions.
The letter below will describe the features and changes over
the beta version. Since I had the extra time, I also corrected the program to
allow for the insertion of drag forces in the Flexible diaphragm analysis that
might occur at the junction of two adjacent flexible blocks. You are warned to
be sure that both blocks reflect the shared reaction from each side of the
diaphragm in the similar grid number associated with each block.
This
spreadsheet has been protected, however, no password is issued (when unprotecting the workbook, leave the password blank) should
you wish to study the code and offer improvements. I have protected it simply
to prevent overwriting important values and formulas. As a rule of
thumb, anything in a shaded cell is input. Some cells that are shaded have
formulas in them. However, you may override the formulas. To reset the cells,
you will need to open a new spreadsheet version of the template and copy and
past from one workbook to the next.
Sorry – I’ll have this automated in the future release.
The delay was due to the fact that the flexible diaphragm
shear distribution was not working as I had planed. To compensate, I wrote the
spreadsheet code based on assumptions that shear is distributed proportionally
into the level below based on the relationship of tributary shear divided by
total diaphragm or story shear.
Therefore for the shear distributed from the roof to the
second floor walls at grid line C will be:
The total Force from roof * Shear at any
grid line in the level below and divided by the total story shear in the level
below. (Easier done than said) I
think that as you work with the numbers you will feel more confident about the
method and about the conservative values that are derived.
I have also removed the Bubbles from the Diaphragm analysis
worksheets. Although I like the appearance of the bubbles, working with them is
a pain. Anytime a cell needed to be resized the bubbles would distort. I
believe that it is simply easier to define the diaphragm width as “left column”
TO “right Column” – therefore the input format (actually anything you want) is
1 to 2 or A to B. This is not used anywhere else in the spreadsheet at this
time. I expect that I will extract values from your input to be used to cut out
a step or two in defining columns in other areas of the workbook.
On worksheets SWD (Shear Wall Design) you will find that
wall deflection is calculated. If the deflection exceeds L/240 the cell turns
red as a warning that you have exceeded the allowable story drift. You may need
to return to the shear distribution worksheet SS to add or lengthen walls used.
IMPORTANT INSTRUCTION ON GRID LINES
I believe this is mentioned later on in this document but I
think it bears repeating so that everyone understands the nature of the
program. You should define your shearwalls from the first level up. Each line
of shear should be defined as a column or grid line and each grid line should
appear on every level. THIS IS IMPORTANT because the program distributes load
by proportioning shear based on an elaborate table which is hidden from view.
This may become on of the debatable issues because,
theoretically, you may have a diaphragm span farther than two grid lines
because there are no walls to resist the diaphragm at the level below.
Therefore, the deflection of the diaphragm may be larger.
I made the assumption that in buildings with a large number
of interior walls used for shear, the diaphragm will never be considered
flexible. The results of the analysis to determine the recommended procedure
(rigid or flexible) will no longer matter as the program defaults to an
envelope solution.
Let me get back to why the grid lines must project through
each level. In the load distribution worksheet, the designer has the ability to
define the location of shearwalls. The walls do not have to stack as the
program determines by proportionality the amount of load that is distributed to
all lines of shear. It’s easier to play with the program and actually see the
numbers rebalance than to explain the process.
The calculated distance between shearwalls (it identifies
grid lines with no shear elements and combines these distances) distributes the
loads.
The program then calculates the full load from the level
above and proportions it into the level below – by comparing reaction shear to total
shear (see section above for more information).
Be somewhat realistic in describing lines of shear. In other
words, if a grid line is five feet or less away from an adjacent gridline
above, there is an assumption that the shear can be transferred through the
diaphragm sheathing and that the grids can be combined. This is an engineering
judgement that the designer needs to make.
Please feel to send me your comments. I am interested in
receiving feedback on the use of this program.
Dennis
October 14, 1999
Re: Final Release version of 1997 UBC Lateral Design
Spreadsheet
To: All interested designers
From: Dennis S. Wish PE
I am pleased to announce the final release of the 1997
Uniform Building Code Lateral Design Spreadsheet. A great deal of work has gone
into this version and great efforts were taken to insure its accuracy.
WARNING: There were
few responses to the Beta version and most of the data checking was done in the
process of using the program to design small projects in my office. Therefore,
I want to warn all users to verify your results and verify the answers you
obtain with this spreadsheet against a known example or sample problem. I would
recommend that you spend time learning to use the program by solving a problem
that you have already designed manually and which you feel confident about your
results. Please notify me immediately if there is a noticeable discrepancy
between your results and the results obtained by this tool.
The remainder of this letter is an erratum that you received
with each beta version. There are features that were added and some were
deleted from those documented. Decisions were made to insure a working version
as quickly as possible, while other features, although desirable, will be left
for development in future versions.
Features Removed:
1. Unfortunately, there is no easy means to maneuver around
the workbook other than by the tabs at the bottom of the sheet. I had developed
a menu system but found that it did not work reliably and, as the spreadsheet
grew, became equally cumbersome. I do intend to add buttons to the sheets,
which will help to move around the workbook easier.
2. The macro to input data from a cad drawing has been
temporarily removed. This will be the first feature to be added back in and I
expect this to be ready in the next week or so. I had some difficulty with this
feature and need to study it some more before including it as part of the
package.
Features Changed:
Conservative
Results
At this time there is debate occurring as to the whether the
design of wood structures should be done by Flexible or R 21421i83v igid design (depending
on diaphragm Deflection results) OR by an envelope method. THIS SPREADSHEET
ASSUMES THE MOST CONSERVATIVE ASSUMPTIONS AND RESORTS TO AN ENVELOPE SOLUTION.
In addition, the applied loads used in the torsion analysis are accumulated
from the flexible analysis as the summation of all worst case reactions
(seismic compared to wind) in each direction. The user may, at their
discretion, override the default formula in the Px and Py applied load
cells of the spreadsheet.
It is recommended that you copy the cells to another
location and cut and paste them back into place should you decide to use the
default values rather than a less conservative approach. To make it easier on the
user, each load at each level and in each direction is given a range name
associated to the block and workbook that it originated in. There is a note
attached to the Load cells in the torsion analysis that explains how the range
name was developed. The range name will be in the form of B1FEW01 which refers
to Block 1, Force in East-West direction, at lowest level 01.
Flexible Analysis
The program allows the user to define up to four blocks –
three stories each. Each block can have up to 40 shearwalls per level in each
direction.
Caution must be taken to insure that diaphragm area’s match
the total areas input for the block used. You can do this by defining the grid
(column) spacing and depth of diaphragm before filling any information in the
worksheet B(x)-SS (where x is the block number). The program multiplies each
area between columns by the gross depth of diaphragm and sums the total areas
to the right of the spreadsheet B(x) – NS or B(x)-EW. The total area may differ
in each direction due to minor discrepancies in defining the area. The program
takes the largest area accumulated in each direction and applies it as a
default to the worksheet B(x) – SS.
You may override the areas manually,
however, if your area is less than the area calculated on the NS or EW sheets,
a red warning will appear to alert you to check your results.
The purpose of this is to calculate the unit shears, which
are a function of the area of the diaphragm. Therefore a warning is given when
the calculated areas exceed that which the user inputs.
You will notice that you are encouraged to override the
default areas at times. This occurs when you have designated areas where the
weight of materials may differ – for example if there is an area of the
diaphragm used as a floor and an adjacent area used as a roof.
You must be alert to the balancing of the areas until some
feature is designed to simplify this for you.
Adjacent blocks and accumulated
shears.
The
user must keep track of the reactions resulting on column lines shared by two
blocks. This release does not combine shears at adjacent blocks automatically.
I expect to have some method of automating this process in the next release.
This may, for the moment, create some difficulty when trying to determine the
stiffness of the wall elements inasmuch as they will be determined
independently in each block.
This
is not a concern on the torsion analysis as the diaphragm is considered to be
homogenous and distribution is complete.
THIS FEATURE HAS BEEN CORRECTED AND INSTALLED. NOTE: THE USE
MUST MANUALLY INSERT THE LOAD AT THE APPROPRIATE COLUMN IN EACH BLOCK. THE
PROGRAM WILL DETERMINE THE REACTION TO BE USE.
Rigid Analysis
There is a question about the accuracy of defining different
materials for stiffness in the Torsion Analysis. The program uses a straight
distribution approach based on the physics of the area. The user can define the
wall stiffness in terms of Modulus of Elasticity, Thickness, capacity
per foot of wall. The program will work out the stiffness (k) factor as a
function of E and t in the Calculations worksheet. The demand to capacity
ration is given in the Output sheet so that the user can aware when the demand
exceeds the capacity of the wall.
The program is, admittedly, keyed more for masonry and
concrete where the stiffness of the wall is more a function of the wall
thickness and modulus.
I URGE ALL OF YOU TO NOTIFY ME OF ANY SUGGESTIONS YOU MAY
HAVE TO BE ABLE TO MODEL MIXED SYSTEMS OF MASONRY, WOOD AND STEEL.
Most of the remaining features are mentioned in the
remainder of this letter. The spreadsheet should be fairly self-explanatory,
although there has been no time to create a useful Help file of other form of
documentation. Any help would be greatly appreciated. Until this occurs, I am
afraid that you must play with the program thoroughly to become familiar with
its features and quirks.
CAUTION:
As I mentioned before, this is a large and complicated
spreadsheet. Every care has been taken to resolve conflicts or errors. I am
sure that some may still exist, but for the most part, you will find these by
error messages such as a #DIV/0 warning. This should not affect accuracy but
may be an inconvenience until enough people have worked with the program and
can advise me of the bugs that need to be found.
I have used the program on four buildings. These were only
one-story structures. To verify the accuracy of a 3-story building, I
duplicated the same structure at each level and compared the results as if each
level represented three separate one-story structures. The only difference (in
the torsion analysis) is the applied load values and these are taken from the
original multi-story distribution sheets in the Flexible diaphragm design
portion.
The program should save the user considerable time and allow
for a good deal of experimentation and “tweaking” of the finished product.
Printing
Print areas have been saved for each sheet. The user must
manually set the printer for each worksheet when a small building is designed.
The default is to print all sheets for a three-story building although this may
not be necessary. You can do this by choosing the page numbers of the worksheet
that you are printing. Refer to the Windows Print help files for more
information.
You may also create print macros that will help you automate
the process. I urge you to share these additional features with the rest of us.
USER IMPROVEMENT
The program is useful
as presented. There are many improvements to be made that will make you more
productive and simplify some of the more tedious tasks. I have spent a great
deal of time to prepare this program which is to be donated to the engineering
community. A few others have also contributed great efforts to the creation of
this program – in particular, David Merrick who
upgraded the torsion analysis considerably. My deepest cudo’s
to David for his efforts.
I can’t impress upon
each of you the importance of creating tools such as this and donating them to
the engineering community to help each of us perform our work in compliance
with the code in the most productive manner. I don’t wish to impede those who
want to create and sell software, but many of us can learn to create our own
tools by studying the efforts of others willing to share their efforts.
Therefore, I urge
each of you to improve upon the software and distribute it for other to learn
and benefit from. If you do this, please send the software back to me at SECONSLTNT@aol.com and I will revise the errata
and track all version numbers and changes. This will help maintain the history
of the software.
Sincerely,
Dennis S. Wish PE
1997 Uniform Building Code Lateral Design Spreadsheet Final
Release Version 1.0
The enclosed spreadsheet is protected by copyright to Dennis
S. Wish, PE and individuals or firms whose additions are incorporated into this
software. This software is Freeware and shall not be licensed, sold,
distributed for profit or incorporated into any other software which is
intended to be distributed for a fee, licensing or which will e sold
commercially with the intention of collecting profit (personal or commercial).
It may, however, be used in the practice of engineering as a productivity tool
and can be used indirectly to generate income.
The software is consider Evolution Ware, the ps generate sucessive upgrades,
improvements, and corrections (where needed) by users who agree to donate the
changed software back to the engineering community for the purpose of Freeware
Distribution.
This spreadsheet is intended as an educational tool for the
learning and understanding of the Wood provisions of the 1997 Uniform Building
Code. The program is to be used at the users
discretion and may be used in any creative manner to achieve results that can
be proven or justified by the user and which will be in compliance with the intent
of the code. The user may, at his or her discretion, modify and or change the
software to fit the needs of the individual for the purpose of satisfying the
code intention. The user may not alter this software with the intention of
transfer of monetary funds in any form. The software may be transfered
for monetary value only by non-profit engineering organizations and only with
the express written consent of all parties who participated in the development
of this software. Any and all non-profit organizations who are allowed to
generate income from this software shall not in any manner disturb or prevent
the continued Free access and distribution of this software.
Users understand that this software may contain mistakes,
bugs or other errors which may affect the printed solutions. The accuracy can
not be guaranteed inasmuch as the user has total control and can change any and
all formula’s. All efforts have been taken to insure
the accuracy of this software but the user agrees to hold harmless any individual
or group of individuals who participated in the creation of this software. As
with any professional software, this product is intended to be used by design
individuals with a valid and thorough understanding of the principles of
structural engineering. The authors and contributers
are to be held harmless for any use or misuse of this program. The user shall
review the software to insure that the results are accurate and shall take responsiblity for any and all output. The developers of
this software shall take no responsibility for design drawings resulting from
the values determined by this software. Consequently, the developers take no responsiblity for the finished product. This software is to
be used as both an educational and design tool only with the understanding that
the software is not now nor will most likely be considered a finished product
as long as work continues to be performed in the evolution of this software.
The enclosed spreadsheet is intended to comply with the
provisions of the 1997 Uniform building Code Chapters 16 and 23. The software
is an interpretation of the written code and may contain inacuracies
that reflect different interpretations of the same code. Whenever possible, I
will have tried to explain who the results were derived. The software uses
tables published in the code which have been reproduced in the spreadsheet to
act as a database for the choice of values based upon a given variable chosen.
Errata (most
current revisions are listed first).
 
July 21, 1999 Beta
V1.0721
 
First, I would like to thank those of you who have sent me
comments and feedback by email. Only a few of you have done so, but your
comments were both useful and informative. I receive constructive critism that yielded some very good suggestions. I have
maintained a record of these and have incorporated as many as possible. As I
upgrade the program (I think this will be a never ending process) I will add
more and more.
I am admittedly ignorant of Visual Basic programing
and was not able to accomplish some of the slicker techniques I wanted in the
program. You will notice, if you are a student of spreadsheet programing, that I have worked out solutions that are, at
times, convoluted but do get the job done. I welcome anyone who can show me how
to simplify some of these methods.
This version incorporates the Torsional
analysis by James Lord and David Merrick into the
spreadsheet. It is, at this point, only capable of working on one level. In the
next week , this will be my primary focus to add the
next two levels and integrate the information from the first portion of the
workbook. I need to take a small hiatus to complete a one story project that
was the main reason for creating the software. Unfortunately, my clients are
not willing to wait much longer.
The Torsional Analysis is
essentially the rigid diaphragm Spreadsheet created a few years ago by James
Lord, S.E. (a member of SEAONC). One of our list
members, David Merrick, P.E. did some major
modifications to the spreadsheet that allows skewed shearwalls to be input. He
as rewritten the calculations for Center of Gravity as well and has also
provided a macro that will extract data from an AutoCad drawing. I was unable
to get the Macro to work and notified David. He seems to have had luck with it
so I left it in the program in case the problem was on my end. At any rate, if
any of you find it works well, I would be appreciate hearing from you.
For those,
like me who were unable to use the macro, I will offer the
following suggestion for how to extract data easier than by working your way
around a blue line set of drawings with pencil and paper.
Extracting Data:
The goal is to use AutoCad’s
“List” command to give the coordinates for all walls and the
perimeter polyline. You will then simply Cut and paste the information from the AutoCad text screen
to Wordpad or any other text editor. This may not
work well if you are using a DOS version of Autocad (it will work if you run
Autocad from a DOS window). This method should work for any Autocad compatible
program. I have checked it with Intellicad as well and believe that it also
works with IMSI’s Visual Cadd 3.0. It is a bit tedius
but less so than trying to pick up points off a drawing.
1. Isoloate a polyline
representing the perimeter of the diaprhagm under
consideration and place it on a separate layer.
2. Create a layer for Shearwalls and use a single line over
the exterior side of outside walls that represent the shearwalls length. You
can use either side of the wall for the interior,
however, the most accurate results will occur if the line is in the center of
the wall thickness (ie, 2-3/4″ for a 2×6 wall).
3. Use the Autocad command “Units” to change the
default units to Engineering. This will give wall lengths in decimal inches. It
would be easier to work with decimal feet, but I was unable to figure out how
to setup Autocad for anything other than their default feet and decimal inches
or simply inches.
NOTE: The coordinates will be given in inches which you can
input on the Wall Worksheet in the Torsion section. This will be converted to
decimal feet on the Input-Output sheet automatically. If you do work in decimal
feet you can enter the information directly to the Input-Output sheet.
4. Turn off all layer other than
the two you just created.
5. Locate the farthest left most point and the bottom most
point and draw a horizontal and vertical line that convergest
to a “datum” point at the lower left.
6. For simplicity sake, Move the objects on both layers so
that the “datum” point becomes 0,0 (origin).
This will insure that the X and Y axis of the sketch or Chart is outside of the
structure.
7. Use the List command and first chose the exterior diaprhagm polyline. Hit the F2
button (function key) and highlight the coordinates shown on the Autocad Text
Window. Copy and Paste the information to any text editor and save it.
8. Turn off the layer that the Diaphragm polyline
was on and repeat the instruction (7) above. This will capture the wall
coordinates. Carefull here, the coordinates are
displayed screen by screen and requires you to hit ENTER each time for a new
member. It is best to copy and past the information from each screen to your
text editor as you go along.
9. Save the file when finished as it will contain all of the
information you need to complete the torsion analysis geometry.
NOTE: IF ANY OF YOU KNOW OF A METHOD FOR EXTRACTING THE
COORDINATES INTO A SPREADSHEET FILE, PLEASE LET ME KNOW. THERE IS A WAY TO EXTRACT
THE INFORMATION FROM A DXF FILE BUT I HAVE NOT SPENT ENOUGH TIME PLAYING WITH
THE DXF FILES TO AUTOMATE THE PROCESS. PLEASE TRY AND HELP WITH THIS AREA AS IT
IS THE MOST TEDIOUS. I HAVE SPENT A GREAT DEAL OF TIME SEARCHING THE INTERNET
FOR MACROS AND INFORMATION ON PARSING INFORMATION AND UNDERSTANDING THE DXF
DATABASE. THIS LOOKS PRETTY STRAIGHT FORWARD BUT I WAS UNABLE TO FIGURE OUT HOW
TO WRITE THE VISUAL BASIC CODE.
The rest of the torsion analysis information will be
mentioned below.
Changes, Revisions
and Modifications:
1. I have decided to remove the multiple block capabilities.
The size of the progam keeps growing and is over 2.5 megs which may create a problem for those of you with older
machines. I also have a concern that as the program grows it becomes
increasingly more difficult to keep track of the information. Adding more
blocks requires that the program more than triple in size. I believe that it
would be much easier to save the workbook as a new name and change the block
information for each unique portion area.
2. I have again upgraded the floating toolbar that helps
navigate the spreadsheet. One problem that I have is that if you change the
name of the spreadsheet, the toolbar macros no longer work. I have not been
able to get any information off the knowledgebase or
help files (or the excel users groups) to explain how to set the toolbar to
work in any worksheet renamed from the original. IF ANY OF YOU HAS AN ANSWER
FOR THIS, PLEASE LET ME KNOW.
3. I Expanded the Torsional
Analysis to 40 walls at each level (only one level is ready at this time). THERE IS CURRENTLY
NO LINK BETWEEN THE TORSION ANALYSIS INFORMATION AND THE INFORMATION INPUT IN
THE FLEXIBLE ANALYSIS, COVER SHEET OR THE LOADS SPREADSHEET. THIS WILL CHANGE,
BUT FOR NOW THE INFORMATION MUST BE HANDLED MANUALLY.
4. The floating toolbar can be docked at any edge of your
screen. Drag it with your mouse to the sides or below the top toolbar and it
will integrate itself into the perimeter of the screen. I left it floating so
that you will take notice of it.
Philosophical Changes
Obviously, the program will work almost flawlessly if you
are modeling a rectangular building. However, I tend to get the more
complicated, unusually shaped custom homes (See the sketch on the Wall
Worksheet) that force me (and you I am sure) to think creativly
about this new methodology.
The flexible diaphragm analysis takes the old tried and true
method of using tributary distribution to distribut
the loads through the diaphragm. Rather than rehash the methodology, refer to
the notes from the prior version to bring yourself up to date (they are sequentually numbered with the oldest notes appearing at
the end of this file). There are some
things that you must keep track of:
A) The area input on the Structural System Worksheet must
equal the sum of the areas occuring between gridlines
that are calculated on the Block #1 N-S and E-W sheets. Inasmuch as you have
total control over the geometry of each subset of the total block, you need to
be sure that the area calculations balance or the unit shears will not be acurate.
HINT: Dimension the Grid Lines starting from the lowest level up
to the roof. There should be a grid line representing every line of shear in
the building. Since the walls may not stack, some levels will have grid lines
where no walls occur (these walls occur at other levels).
Make sure that the sum of the spans between grid lines does
not exceed the physical width of the building (in each direction). The diaphragm depths between each grid line
may increase or decrease. The total area is calcuated
from the Summation of the gross depth of the diaprhagm
(between gridlines) times the span. BE SURE TO CHECK THE SUM OF THESE AREAS
AGAINST THE SIZE OF THE AREA INPUT ON THE STRUCTURAL SYSTEMS SHEET.
Refer to the notes below for
version V1.0715 for conditional statements added to the cells to avoid
exceeding the wall maximum shear capacity or the code allowable H/b ratio.
I completed the Shearwall
Deflection analysis. I had to make a decision as to how much
“Tweaking” you could do in order to get all of the walls in any one
line of shear to deflect at close to the same rate. IMPORTANT: I believed
that it was not practical to try and change variables for multiple walls in any one line
so as to match stiffness. The reality is that it will be next to impossible to
control in construction. It is much easier to deal with masonry, concrete and
steel shear wall construction because the trades are more specialized and
familiar with constructing piers with differing levels of reinforcement. In
wood, plywood is typically applied by a subcontractor who gets paid by the
panel. My experience has been that unskilled labor is used to nail panels and
nails are spaced “as close as possible to the shearwall
schedule”. However, most contractors take the position that it is better
to install more nails closer together than take the time to measure off the
actual spacing. Therefore, it is common to find walls which are specified at
6″ on center to be nailed closer to 4″ and often some at greater than
6″ and closer to 3″.
Until this revision to the code, stiffness was not a factor.
I personally believe that we will not be able to control exact spacing of nails
and that the wall stiffness will vary from wall to wall due to construction
practices.
Therefore, I made the walls
adjustable as a group and only allowed for minor changes such as the size of
the King Studs or posts at each end of a wall panel. This is reasonable as the requirments for holddowns will control the size of the
tension and compression chords.
The shearwall
deflection sheet breaks down each of the four terms in the deflection formula
so that the designer can compare the results of each term to see what term differs the most.
The analysis also calcualtes the stiffness factors K for the individual wall
sections and the sum of the sections in each gridline.
I have not incorporated an
analysis for shearwalls with openings. I am not sure at this time how to do
this (or how to add deflection calculations for walls that don’t stack and
occur above beams). These may need to be done manually and the stiffness
“tweaked” separately.
CM & CR
This next section calculates the Center of Mass and the Center of Rotation for each area at each level.
This is where the First half of the Workbook comes to an end. It was my
intention to jump into the Torsion analysis for each of these
“simple” blocks. I ran into a problem trying to interprest
the design example problems from the SEAOSC ’97 UBC Wood seminar and the first
draft of the Volumn II of the ICBO Design Manual for
the ’97 UBC. I specialize in wood and was not familiar enough with torsional analysis to understand where the author’s
dimensions came from. I will complete this section in the near future.
LIMITATION
The block method of analysis as I have been explaining does
not take into consideration skewed walls. I am faced with this in my first
project under this code. I plan to use the examples provided the the second section by David Merrick
for the analysis of the Center of Gravity to change the program and to allowed
for unusually shaped blocks and skewed wall sections.
PART II – TORSIONAL
ANALYSIS
NOTE: SECTION II OF
THE WORKBOOK IS INDEPENDENT OF THE FIRST SECTION. ALL COORDINATES TO DETERMINE
THE AREA OF THE DIAPHRAGMS MUST BE CALCULATED SEPARATELY. THE USER MUST
TRANSFER THE DIAPHRAM FORCES AND LOCATION OF SHEARWALLS FROM THE FIRST HALF TO
THE TORSION ANALYSIS MANUALLY AND CAUTION SHOULD BE TAKEN THAT THE GEOMETRY IS
CONSISTENT. THESE NEEDS WILL BE ADDRESSED IN FUTURE UPDATES BUT THE PROGRAM IS
STILL USABLE AS LONG AS THE DESIGNER IS AWARE OF THE LIMITATIONS.
The first thing you should notice (after reading the two
note sheets embedded in the spreadsheet) is the sheet titled “Wall
Worksheet”. I have input the plan of the project that I am currently
trying to complete. This example has created a number of challenges and
questions that I need to answer, but both James Lord SE and David Merrick have helped considerably with their donations.
1. Refer to the instructions for inputing
the coordinates of the diaphragm area from a CAD drawing. All dimensions shown
on this sheet are in inches due to the limits of the Autocad units. The
coordinates are referenced to the Input-Output sheet where they are divided by
12 to convert them to feet so as to be in compatible units with the analysis.
YOU MAY OVER-RIDE THE PROGRAM AND ENTER FEET DIRECTLY INTO THE INPUT-OUTPUT
SHEET, HOWEVER, YOU WILL REMOVE THE CELL FORMULA AND WILL NO LONGER BE ABLE TO
CONVERT A CAD (INCH) DRAWING IN THIS WORKBOOK. YOU ARE, HOWEVER, ABLE TO
REWRITE THE FORMULA. I WOULD RECOMMEND THAT YOU CUT AND PASTE ONE CELL TO AN
INCONSPICOUS CELL IN THE INPUT-OUTPUT SHEET SO THAT YOU CAN PASTE IT BACK LATER
AND COPY IT ALL LOWER CELLS. THIS WILL REINSTATE THE INCH TO FEET CAPABILITIES.
2. You are allowed to specify different wall materials
(concrete, wood, steel etc.) in the Wall Type boxes located on the Input-Output
worksheet in cells B56-F65. If you use all the same type of wall, you can enter
a 1 in the E column and t columns. These are relative and will cancle out if all walls are of the same materials.
TIP: YOU CAN DEFINE STEEL COLUMNS AND WOOD IN THIS SECTION
SO THAT THE PROGRAM WILL CONSIDER THE STIFFNESS OF THE DIFFERENT MATERIALS IN
THE TORSION ANALYSIS. YOU CAN ALSO DEFINE A NUMBER OF SHEARWALLS BY CAPACITY (IE., 320 PLF = 0.32 K/FT). THIS LETS YOU DEFINE A TYPE OF
SHEARWALL FOR EACH WALL SECTION (40 WALLS PER LEVEL BUT ONLY 10 DIFFERENT TYPES
OF SHEARWALLS – WHICH SHOULD BE SUFFICIENT ).
SUMMARY
The final portion of the workbook will compare shears in
each line. The problem here is that the second half of the workbook can
calculate the torsion and shear by rigidity of diffiult
geometries while the first half is limited to smaller
simpler geometries. To be consistent, you would need
to break apart the diprhagm into sections that would
allow both sections of the workbook to compare similar geometries.
This would simplify the next step of creating a summary to determine the
variations between flexible and rigid diaphragms.
If, however, the structure is relativly
regular in shape (square or rectangular), modeling the entire structure is easy
and straight forward. Unfortunately, this is not typical of the conditions I
face in custom homes. This is where, in my opinion, the Seismology committee
has failed to understand the complexity that they created by required the
method of wood and expected that all materials will essetially
perform the same. In some ways this may be true, but the amount of work
required to find a relativly insignificant difference
will cause many of us a lot of sleepless hours.
****** IMPORTANT
CODE CONCERNS WHICH NEED TO BE RESOLVED**********
It appears from working through the design examples that
under ideal conditions the goal is to design the struture
so that all walls deflect with the same relative stiffness. The code does not
suggest what should be done to “tweak out” the walls nor does it
explain what to do when stiffness differes from grid
line to grid line or between walls in each grid line.
As I have stated in the summary above, it does not seem
practical in wood framing to tweak out walls to specifically. You may be able
to reduce your liablity, but will have a great deal
of trouble controling the quality of construction in
the field. If the Building Industry does not take some responsiblity
to require those who build these structural systems to be certified and
educated with special knowledge of the code, there can be no quality control
that will be be effective and you, as the engineer of
record, still remains liable under the Strutural Observation
guidelines.
There have been many discussions both public and private on
the SEAINT Listservice regarding these topics and most engineers supporting the
code feel that we need to design both ways and to identify the effects of torson on our structures. However, arbitrarily adding
stiffness will change the distribution of torsion and may not yeild ideal results.
The code requires the design of wind, and in most cases,
wind will still govern in wood design. Wind is a uniform load that will not be
affected by the geometry of the structure as in seismic design. With uniform
loading, the rotational differences do not appear to be as great as when
seismic controls. Therefore, one of the underlying questions is “If wind
controls, can torsion be ignored and the resisting walls designed by rigidity
to keep the same stiffness in each line of shear?”
Now that the aspect ratio of the walls are
greatly impacted by the new code, I suspect that we will start to see more
proprietary shearwall systems like the Hardy Frames
or Simpson Strongwalls. How are
these frames suppose to be modeled in this program? You can not simply
substitute these propriatary frames for wood walls
without knowing their stiffness factors. Yet I suspect that engineers will want
to substitute one Hardy frame for four various shearwalls in one gridline so as
to simplify the analysis. Does this force us back into manual calculations to
readjust the shear?
How do we treat field changes when the owner decides he
wants to add walls or remove walls – or wants to enlarge walls during the
course of construction. Any minor change such as this
will require rebalancing the entire structure and a
change in one area may affect the torsional shear in
another area. How do we explain this to our clients?
There are a great number of problems with the new code as it
applies to residential construction that needs to be addressed and quickly. I
am interested in any comments from my peers.
Dennis S. Wish PE.
PROBABLY MORE NOW THAN IN THE PAST, YOUR COMMENTS ARE MOST
IMPORTANT. THE TWO PORTIONS OF THE WORKBOOK NEED TO BE TIED TOGETHER
AND I AM STRUGGLING WITH THE BEST
WAY TO HANDLE WITH WITHOUT DESTROYING THE PROGRAMS
CREATIVITY. I WOULD APPRECIATE ANY
GUIDANCE I CAN GET FROM THE 150 OF YOU WHO RECEIVE THIS PROGRAM. YOUR OPINIONS
AND COMMENTS ARE VERY MUCH APPRECIATED.
 
July 15, 1999 Beta
V1.0715
 
There have been a few major changes and I recommend
that you delete all previous versions. The changes are not so much in additions
as they are in corrections and subtle changes to prepare for the next steps in
the design process.
1) The first obvious addition is a floating toolbar that
assists in moving from worksheet to worksheet. If you are modifying the
spreadsheet, you will not be able to use the macro from within another command
and will need to use the tabs at the bottom of the workbook. In the future, you
will be able to access the print macros from this menu.
2) Although a minor change, you can now customize the title
block on the Cover sheet and most of the changes will be reflected on each
subsequent worksheet. This includes the Company name, company address, job
number, job name, designer and checker input. The graphic can be eliminated or
replaced with your own graphic logo or it can be modified within the graphic
tools in Excel – however, you must manually replace the logo on each sheet.
3) The comparison between wind and seismic was not accurate.
The problem did not surface until I started to play with different values and
noticed that the uniform shear v increased and decreased with changes in the
span between shear panels (gridlines). The reason is that the first term of the
deflection formula has been converted to use the diaphragms unit shear. The
wind load is a function of the height of the building and is applied to the
span between grid lines. Normally, we would do the same thing when calculating
seismic shear to the structure. In this case it is different. The design
example calculates the diaprhagm shear stress at each
level so as to allow the designer to compare the diaphragms capacity to this
demand. This is to alert the user if the capacity is exceeded to allow for
changes in panel nailing, thickness etc.
The first term of the deflection formula is 5 v L^3 / (8 E A b) The term ‘ v ‘ is the diaprhagm
shear stress calculated along the depth of the diaphragm (b dimension). The difference in the formula compared to the
typical beam deflection formula is two fold and maybe it is a good idea to
explain it as it was explained to me.
Start with the beam deflection – Delta = 5 w L^4 / (384 E I)
Since v is a function of w, then v = wL/(2b) AND w = 2 v b /
L
This next part was difficult for me to grasp since I tried
to convert the Moment of Inertia working in plan view. The trick was to learn
that the effect of the I value was along the
diaphragms thickness. The first term calculates the I
between the chords and disregards the I of the sheathing (which is left to the
second term of the formula). I = Sum (Ad^2)
d = b/2 (the distance between the chords and to the neutral
axis)
Since there are two chords the term becomes: I = 2A (12 b/2)^2 (12 is used to convert units) I = 72 A b^2
Substituting terms:
Delta = 5 v L^3 / (8 E A b)
Finally, to compare seismic to wind you need to either
convert ‘v’ back to w or convert wind to a diaphram
unit shear along b. The later is easier
to do since it does not require a convoluted way to reconvert back for the
deflection formula. Therefore, the new term for uniform wind load is actually
the reaction of the wind load between gridlines divided by the net depth of the
diaphragm ( wind * L / (2 b) )
4) The next step was to convert back to a uniform applied
load ‘ w ‘ in the Flexible Diaprhagm shear wall
analysis. I won’t go into the steps that it took, but this actually worked out
to be pretty straight forward.
5) The Flexible Diaphragm Shear distribution sheet some other changes and is still not finished (however,
it is usable). The most noted change are the limits
placed on shear values and wall capacity:
a) When the shearwall aspect ratio exceeds 2:1, the cell containing the
wall length turns red as a warning.
b) When the unit
shear exceeds 1100 pounds per foot, the cell containing the capacity turns red
and the cell indicating the number of sides to sheath indicates the word
“FAIL” to alert the designer that they are exceeding the code’s
allowable wall values.
6) The appearance of the sheet has changed just to simplfy the processes of expanding the use of the sheet.
This will include the thickness, structural grade, nail size and spacing. The
information from this will be summarized in a shearwall
schedule later.
There have been some other minor changes which have been
made – mostly in appearance and to correct a few minor mistakes. As always, please feed your comments and
suggestions to me and I’ll see what I can do to incorporate them into the
program.
 
July 12, 1999
1) The first change you will notice is the the name change.
July 12, 1999 RDV10712.Zip which stands for: Residential Design Version
1.”post date”. zip
or exe
I have had some email me that their
downloads were truncated and the Zip file was damaged. I am shortening
the file name tso as to conform to the 8.3 DOS name requirments. This may have not benifit
other than to try and reduce any possible problems associated with long file
names and email transmission.
2). There is a major change to the logic which is in the programing and not visible. This occurs in Worksheet
“Block #1 Flexible Diaphragm” (refer to tables located at the range AB35 to
CO53). The conditional statement tested
for the number 1 which reprented the presence of
shear walls in any of the grid lines at each level. If the number 1 was
detected, the grid line was assumed to have shear
resisting elements. Any other number was considered to mean that no shearwalls occured.
I did not plan ahead well enough and realized this morning
that I could use this input to define the number of resisting elements (walls)
in each grid line. Therefore I needed to change the conditional statments to recognize the lack of shearwalls or the number
zero.
This became a time consuming change because the order of the
conditional statement also needed to be changed to avoid rewriting hundreds of
formulas. This took most of the day be provides a much more flexible means to
account for an unlimited number of shearwalls in each grid line.
The purpose of this is to create a means to test wall
rigidity and to try and make all the walls the same stiffness.
This is where I have stopped today and will continue to work
on the sheet tonight and the rest of the week.
TIPS:
In the course of writing the spreadsheet, I began to see the
relationship between materials and shear distribution. There are a number of
Theories which I came away with to help simplify the design process. These are
debatable and you might want to rack your minds finding flaws in the logic.
1. Forget about separating materials by stiffness (ie.,
steel columns or plywood shearwalls). As long as you know how to run a deflection
calculation, if you design the elements to deflect the same amount, you have
matched stiffness.
2. One major conclusion drawn by many engineers is that in
the case of an open front type structure (garage, retail store) the rear walls
are much stiffer than the front. To compensate will require a much larger steel
section – in other words the columns will be very large to match the deflection
of the back wall. What many are forgetting is that the back wall does not have
to be as stiff. Rather than sheath the entire back wall for shear, design the
plywood walls to be less stiff so as to come closer to matching a lighter steel
column that still does not exceed the allowable story drift. This will yield a
more ecconomical design by reducing the amount of plywood
and mechanical connectors and reducing the size of the embedded steel columns.
3. I’ve said this one before (see below),
it is a known fact that you can not create a rigid moment resisting connection
between two pieces of wood without embedding one in a foundation (flagpole).
Therefore, you can not make a joint between two block
“L” or “U” shaped structure that will have zero
rotation. Because of this, you can not
treat a “L” or “U” shaped
structure as rigid and design the entire shape for torsion.
You can, however, break the shape into it’s
basic elements (blocks) and treat each block as though it were rigid. If you do
this you have a possiblity that the torsional shear applied at the common end will work in the
opposite direction and cancle out the torsion from
the adjacent block.
Since the two blocks can not be rigidly connected, I would
recommend that the torsional shears be additive only
(not following sign convention) and thuse yeild more conservative results.
This would justify the use of this spreadsheet to reduce
complicated shapes into basic and easier to analyze blocks. It does mean more
analysis (a full analysis required for each block) but isn’t this what the
spreadsheet is suppose to simplify.
4. Simplify the design further by limiting the aspect ratio
of all shearwalls in the same grid line to be the same. In most cases this is
possible. Where piers are limited and the shorter pier must control, you can
make the deflections uniform by using proprietary shear elements like the Hardy
Frame or Hardy Panel from Simplified Structural Systems. The advantage is that
you can use an R value between 4.5 and 5.5 which means that you are not
penalized as you are with embedded columns and these proprietary systems are
much stiffer than conventional plywood shearwalls (ie.
about 4,000 lbs of shear in a 4×8 panel). CAUTION: be
sure that your foundation is designed appropriately for the use of these walls.
Hardy recommends using (2) #4 bars at the top and (2) #4 bars at the bottom of
the foundation and extending the bars 3′-0″ past each end of the wall or
wrapping the steel for 3’-0″ around a corner. Don’t neglect the uplift forces which means that at the front of a garage you are
safer to design a continuous grade beam than to eliminate the beam between
garage door piers.
5. Use the spreadsheet to help you understand the
relationship between the code variables. I have learned a great deal about the
new code from the creation of this worksheet and the discussions/debates I’ve
had on the List. Take the time to delve into it – I think you will feel
confident about using the code once you do (and at least somewhat frustrated
about those methods that you don’t agree with).
July 10, 1999
The lateral distribution to shearwalls by flexible diaprhagm analysis is now in the process of being
completed. It is important that the following guidelines be strictly adhered to
so as to insure accurate results:
1. All Lines of Shear in each block must be accounted for at
each level in the Diaprhagm Deflection analysis. The
spans used in the Diaphragm Deflection Calculations are referenced to the
Shearwall analysis. The governing shear between each grid line is also
referenced from the Shear Wall distribution.
For example, if you have a shear wall occuring
on one level and not on another, that shearwall must
have an appropriate grid line associated to it at all levels. Assume you have
two walls at the roof and three at the second floor. Each level must have three
gridlines (you can consider the middle grid line to be a “ghost” of
the wall at the level below. The purpose for doing this is to allow for
distribution of shear to walls that do not stack. If you look at the tables
used on the Flexible Shear Distribution Worksheet you should see the
relationship of how shears are cumulated. The uniform forces are summed on each
side of the shear wall and are dependent upon where walls are indicated and
where they are omitted (because of the “ghost” wall at the level
below).
This may not be the most elegant way to deal with the programing but it seems to work just fine and makes it much
easier to track loads.
2. There were corrections made to some of the Load sheets. I
noticed that some of the Combo boxes did not appear on sheets that were copied
for the three structural systems. They
are now fixed.
3. The spacing between grid lines are now fixed at all
levels. This is to insure accurate results for non-stacking walls. If you
decide to add a wall to a lower level, you need to go back, to the roof and
change the grid spacings. Possibly someone can help
determine an easier way to handle this – still, you save a lot of time over
doing it by hand:>)
4. A background pattern (appropriately called wood.bmp) is included in this revision. You do not need to
use it, but it will make your spreadsheet easier to stare at and will not print
as output.
5. Diaphragms are now refered to
by level. A three story structure will have a Roof, Second and First level. I
decided to standardize this because some 2 story residences need to consider
the first floor as a level if it is framed above a cripple wall. Therefore, the
program becomes limited to levels rather than stories. For somewhat selfish
reasons, I have no specific need for anything greater than a two story design
program due to the height restrictions here in the desert. The Palm SpringsCalifornia
area limits building heights to preserve a valley view of the surrounding
mountains. I encourage anyone who needs more levels to expand the program and
offer it back to the rest of our users (currently over 120) who may benifit. Sorry, but this is starting to cut into billable
time and I need to complete the program for a project that is quickly
approaching it’s due date.
HELP WANTED
We are in need of either custom pulldown
menus to navigate the spreadsheet and macros to automate the printing process.
The spreadsheet is growing rapidly in size and I guestimate it will reach
somewhere around 3Mb in size. If anyone can help create a Navigation Floating
Toolbar, it would be very helpful.
Other issues:
I am seriously considering changing the program to allow
appropriate design for any type of building. This does not appear to be
difficult. It needs to consider the Rho and Omega factors for mixed structural
systems. This will be down the road a
bit, but I intend to make the modifications so that we are not restricted by
occupancy type.
Comments:
Please let me know your comments and suggestions. Most of
all, please let me know if you find inaccurate results – these need immediate
attention (a few compliments wouldn’t hurt either:>)
July 8, 1999
This version of the spreadsheet represents a pre-release
version that is only partially complete. The spreadsheet follows the
methodology presented in from the 1998 seminar held by Structural Engineers
Association of Southern California “1997 Uniform Building Code (UBC) Wood
Provisions” (Feb. 21, 1998). However, I have provided certain changes that
reflect my professional interpretation of the wood frameing
code. These include the following:
1. Wood structures with wood diaphragms are neither entirely
rigid nor entirely flexible. Therefore, irregular shaped structures such as
“U” or “L” shaped structures can be broken down into
individual blocks to simplify the design. The reasoning behind this
interpretation is that it is not possible to create a totally rigid wood
connection without embedment of the wood materials. Therefore, where an
“L” shaped building is analyzed, the joint at the connection of the
two legs can not be entirely rigid and will experience rotation which
translates into a pinned connection. The user who does not agree with this
opinion should be warned not to use the software to design independent blocks.
2. I have been advised that the diaphragm deflection
calculation is an emperical based formula and that
the units will not balance. Users are urged to satisfy themselves that the
results of these formula are accurate and valid.
3. As noted above, the software is far from complete. The
user is warned to disregard the shearwall analysis
and subsequent graph and schedules. These are left over from the one story
flexible design spreadsheet that was used for layout. The workbook sheets to
the right of that labled Block #3 E-W is not valid at this
time and should be eliminated or ignored.
4. All tables are included in each worksheet. Printed page
area’s are defined (use the preview button to see the limits of what will be
printed). All tables are added to the right of the print area. It was my
original intention to hide the tables from view to discourage inappropriate
changes. However, the spreadsheet is offered to allow the user to modify or
improve it as they see fit. therefore, all tables are accessible and nothing is
protected on the spreadsheet.
5. ActiveX controls have been added. These are very simple
to use. A table at the right of the printable sheet contains a column of
choices which will be visible in the pulldown
Combo box. Each
choice starting at the top is assigned a number beginning with one. The integer
is used to search for other values rather than relying upon text or ranges.
This simplifies the lookup tables as you will not that each table contains
simple integers at the top and sides. Once a variable has been chosen from the
Combo Box the associated integer is written into the cell located below the
combo box. If you right click on the combo box, you can move it out of the way
to verify the location of the written integer. This cell is later used in the Vlookup or Index and Match functions in Excel. The user is
encouraged to build upon the tables and add or change any of the choices.
6. The methodology uses Allowable Stress design. The values
for Ca and Cv have been reduced by 1.4 to convert for
ultimate strength design to allowable stress as indicated in the seminar notes.
Inclusions:
1. The spreadsheet contains the following worksheets:
A) Cover – a generic coversheet used to identify the
project, designer, code and material stresses used throughout the total design
project. No information on this page is used by any other worksheet.
B) Loads – This allows the user to define the materials and
loads used throughout the spreadsheet. Only the Roof I and II, Floor and
Deck/Balcony loads are used in the remainder of the spreadsheet. Exterior and
Interior wall partitions are only listed for the record. The spreadsheet
assumes that 5 psf for roof level and 10 psf for floor levels is arbitrarily
added to the roof and floor diaphragm deadloads. The
wall loads are added to each Structural System Sheet (at the right of the work
sheet) and may be changed or modified by the user. One suggestion has been to
assume a 1 psf load for each vertical foot of combined interior and exterior
walls. Therefore, the formulas can use the actual story height to increase the
generic wall load for taller structures.
Wind Loads – The code still requires the designer to
evaluate wind loads and compare them to the seismic loads on the structure. All
tables for the determination of wind loads are included for levels up to 40
feet. This is pretty self-explanatory. Exposure, Wind speeds are chosen from
pull down combo boxes.
Seismic Loads – incorporates all new code criteria for Near
Source evaluation of base shear. The difference between code and this program
is that the user can evaluate up to three independent blocks with varying strutural systems (which effects the R in each appropriate
direction). The designer must remember that the blocks must be tied together
and the walls in the cumulative line of shear must be balanced by deflection.
The user is cautioned to reference the code and appropriate maps to evaluate
the correct distance to source, soil profiles and seismic source type. The
appropriate base shear will be evaluated for each system type in each block
represented.
C) Structural Systems: The program allows the definition of
three structural systems – with two systems which can be applied to any one
block with only one system for each direction of force. For example, the
designer must chose the worst case structural system for each block and for each
direction of shear. If the system is a combined system (ie,
pendulum or embedded columns and plywood shearwalls) the designer must
stipulate the worst case condition or the appropriate lowest R value. The
results are used in the analysis of each block at each level and in each
direction.
D) Loads N-S and Loads E-W: This is the Diaphragm Deflection
Analysis. To save using the pageup and pagedn keys, a
worksheet has been devoted to each direction. Each block consists of up to
three stories and can be divided into as many as 10 lines of shear. This
worksheet distributes diaphragm shear only (typical multistory lateral
distribution). The block may have different spans between shearwalls and
different gross and net diaphragm depths at each level. The Loads sheets treat
each block as a flexible diaphragm and design deflection between walls as
simply supported beams. Only after the diaphragm is determined to be rigid or
flexible will it be treated as a continuous beam for distribution of shear to
the the resisting walls (not completed as of this
date).
The spreadsheet also calculates wind loads at each level for
comparison to the seismic load. The distribution of shear into the diaprhagm is based upon the controlling shear between each
grid line. Therefore, wind may control in the first gridline (where the
diaphragm depth is small and roof material light) while the adjacent grid line
may have seismic controling. This produces the most
conservative results.
This brings up a questions as to the using shortcut methods
to circumvent rotational analysis should the diaphragm prove rigid. One
engineer suggested that the stiffness of the resisting walls is critical and
that it is not suggested to simplify the approach by using a conservative
uniform load across the entire diaprhagm rather than
the actual loads attributed between grid lines. However, the seminar methods
suggest that the worst case loads be considered in the design of resisting
elements. These will not be true to the torsion determined by the difference in
distance between the center of mass and the center of rotation as any changes
to the implied applied forceses will shift the
distance between the centers. Anyone who
cares, may wish to discuss this with me to see if it is not appropriate to determing the worst condition across the entire block and
to apply only those loads so as to create a more realistic model for the
determination of diaphagm rotation.
The program will determine the number of stories from the
previous Structural Systems sheet and complete the analysis for deflection.
The deflection formula is broken down into its four
basic parts; beam deflection, shear
deflection, nail bending and slippage and chord slippage. The designer has a
virtual complete choice of materials which determines the modulus values G and
E. The user also has a choice of Wet/Dry and Dry/Dry materials that will effect
the use of additional reduction values applicable to nail slippage and bending.
Chords are considered to be spliced with 16d nails and the
constant for 1/32″ or half of the diameter of the 16d nail is used in the
Chord Slippage analysis. If any other nails are to be specified, the formulas
must be changed accordingly. Since the code is specific about chord splices,
the formula assumes the code designated nailing schedule.
Soon to be released:
The program is far from finished. Some time ago I
distributed a rigid diaphagm spreadsheet created by
James Lord, SE. It is my intention to incorporate the spreadsheet into this
one. James Lord’s name will appear as author of this section of the spreadsheet
and is entitled to all copyright protection noted above.
David Merrick PE has donated a
macro routine that will allow for the rigid diaphragm geometry to be
automatically evalutated from an open AutoCad DWG
file. This will save a considerable amount of time in the process of defining
the diaphragm boundaries and the location of shear elements. David Merrick will be credited as the author of this macro and
will be entitled to the same copyright protections as the rest of us.
The shearwall design portion of
the program will work similar to the diaphragm deflection design. The basic
deflection formula will be divided into its separate components so as to allow
the user to identify those elements that are grossly variant. This will allow
the user to focus on the most critical elements that need improvement in order
to save time and iterations in the wall balancing section. I would appreciate
any help from anyone who can create a macro or program that will automate the process
of finding the most ideal solution.
I would also like to create a floating menu system to speed
up movement around various portions of the spreadsheet. I would also like to
automate the printing process using macros. This is fairly easy but will require
some time – which I do not currently have much of.
Any help in the continued creation of this spreadsheet will
be greatly appreciated and all credit will be given where applicable.
Finally, it is imparative that we
have a good manual or set of help files. Can anyone help create these as we
continue the creation. these will help those who follow in our footsteps.
In order for changes to occur consistently, I request that
all improvements be submitted to me at SEAINTONLN@aol.com. I will insure that all
revisions and corrections or improvements are combined and documented
appropriately.
Please feel free to write me and let me know what you think.
I can’t try and make one program that will satisfy everyone so any major
changes will be left to each of you. I will, however, correct any errors or
misinterpretations of the code that need addressing.
Compliments are always appreciated as I would really like to
know how useful you found this tool to be.
Sincerely,
Dennis S. Wish PE
seaintonln@aol.com
Final Disclaimer:
This software is not in any manner associated with
Structural Engineers Assoication International, SEA of Southern
California or any other professional
organizations. It is soely the creation and work of
one or more independent engineers, designers and students who wish to be
voluntarily create a useful tool intended to be freely distributed for the benifit of all.
July 8, 1999 Beta
Version 1.0