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Software for Structural Design of Dwelling Houses
2

Software for Structural Design of Dwelling Houses

Software for Structural Design of Dwelling Houses

(OP)
Hi
I am looking for information on Software for Structural Design of Dwelling Houses,
ie
Foundation Design,
Beam Design
Timber Thrust Roof Design
 

RE: Software for Structural Design of Dwelling Houses

There are only three commercially available programs that I am aware of. Actually two - one of them is free and is a spreadsheet that I designed with another engineer and donated to the public domain for others with spreadsheet knowledge to improve upon and contribute.

AF&PA Woodworks 2002 is the latest software from American Forest and Paper Association (Buddy Showalter from AF&PA is currently on this forum). Woodworks has been around a long time, but it was not until this release that I think they started to focus on the important features and issues. The program will help design the gravity and lateral loads for all structural members of a multi-story structure including (new in 2002) a front end to design the base shear using values from the 97 UBC for Site conditions and Near Source Values (I've only evaluated the demo and don't currently run the full version).
Pluses:
1. Good modules for gravity load design of members with various load conditions.
2. Included NDS (National Design Standard) in PDF format but requires password or unlocking key to access - a negative.
3. Flexibility to allow for changes in shearwall size and location for redistribution of forces using flexible diaphragm analysis and rigid analysis.

Minuses:
1. Input is cumbersome - using a Windows Metafile Format or Autocad DXF (this I am not absolutly sure of) as a background that is first scaled and used to trace over to define bearing wall locations, columns, beams etc.
2. As with the other commercial program on the market, does not allow for flexibility where alternative materials to wood may be used - such as a steel beam or cantilevered column.

Keymark Industries - KeyLat (Model, Structure, Keylat, Plot modules).
This one is part of a very ambitious program that started in the early 90's (possibly earlier) called Intelligent Take-Off at the time. For those who know the name, Keymark has been in the Truss Software business for years and was licensed until around 1994 to produce the Analysis and Design software for Trus-Joist called TJ-Beam.
Keybuilder.Com (pronounced Key Builder Dot Com) is the entire program which claims to design gravity and lateral loads from the roof to foundation and will provide a framing drawing at the same time. The biggest plus is that it is being marketed to teams who will represent developers of homes where the program is used to create a very exacting materials list for bidding.

Plus:
1. Choose the modules you want - priced per license containing the modules you want including gravity, lateral, modeling, truss design and construction managment tools.
2. Keymark combined with the efforts of Simpson Strong-Tie and came up with a Lateral design module that provides accurate output that compares wind and seismic forces in each line of shear (you define) and allows the designer to designate the type of wall (conventional shearwall or propritary Simpson Strong-wall).
3. Multi-story capability will compare flexible and rigid analysis per the 97 UBC
4. Excellent Gravity load design modules that accumulate and distribut forces from each level down so that you don't need to define the loading conditions.
5. Will output elevations of all trusses for distribution to truss companies for construction. Program allows you to buy and use the truss design module, but it is generally safer for an engineer or architect to rely upon a proprietary plated truss company for truss design. Still, the truss elevations provide a clear picture of what the designer wants and easier understanding for the truss company to comply with.

Minus:
1. Difficult and time consuming input of models. However, there are trained Keylat Modeling designers available in and out of house at affordable fees to set up the Model prior to analysis.
2. Horrible security system on the program that extends licenses for up to 61 days at a time (this is an automatic renewal) and will crash if security files are moved by defragment programs.
3. Will not distribute shear in flexible analysis by wall stiffness - only in rigid analysis
4. Typical problem with Woodworks and Keylat - will not distribute shear to model with skewed (non-orthagonal) shearwalls although this can be creatively designed.
5. Will sometimes misinterprete diaphragm shear distribution across a discontinuity such as a small section with a "U" shaped cutout. Shear is distributed by length of wall compared to overall length which means that a garage short panel will be assigned much less shear than it actually will have. This is a case where the user of the program must be careful and understand the software limitations.

There are many pro's and con's to each of the above programs - I can's say which is better, but none of them are ideal YET! Including my own freeware:

David Merrick, SE and I created a good looking spreadsheet after the 97 UBC was codified. I've used it on many single story buildings but it has the capability to design up to four or five stories. This is a lateral design program so don't expect it to design gravity load members. Still, It will design comparing wind and seismic and will calculate base shear based upon specific site conditions (soil, near soruce etc.).

Tributary distribution is done by breaking the structure into blocks and the program will design up to fifty shearwalls per level for each of five blocks. This allows the user to break up a building with skewed walls into separate blocks and manually write in the reactions from each block into the adjacent block.

David Merrick worked on the rigid analysis will has been expanded to allow for various shear resisting materials to be used based upon their stiffnesses. R can be adusted for each block and in each direction so if you have embedded columns working only in one block in one direction, you can increase the base shear accordingly by using an R of 2.2.

The program also allows the user to settle in on a Simplified Static design per UBC Section 1630.1 (I'm recalling from memory and this may be wrong).

The key to this spreadsheet is that the user can be as creative as they want. However, don't work with this spreadsheet if you don't have spreadsheet skills and don't work with it if you don't have the skills to interpret the results.

There are a couple of bugs, but another engineer has been making modifications to the spreadsheet which corrects these bugs and increases the total number of walls to allow the design of a multi-story apartment building with over 350 walls per level.

There are no doc's (I have it on my to-do list to create an online document/tutorial which will be on my website). There are errata sheets and explanations for the logic behind the distribution and formula's. The program was written to follow the ICBO Seismic Design Manual Volume II and additional corrections were added in after debates - such as the use of Rho for light frame wood structures, Multiple diaphphragm dead loads (clear-stories, decks, etc). Although it shows snow loads, they are not implimented as yet.

The one big plus is that there is a macro included to allow Autocad users to define points on their drawings which are then extracted in input into the spreadsheet to quickly recreate the model in two-dimension (you indicate the elevation) and the same macro will define the physical location of all shear walls or shear resisting elements.

There are no macros for printing and although it uses good looking graphics, the user must be able to define the print region for printout.

So which is best - none are ideal (not even my own). There are limitation and there are also not enough consensus from practicing professionals as to what is a standard of professional practice for the design of a light framed wood structure.

Personally, I think Keymark is leading the pack with the number of modules to meet all trades and the ability to get intimately detailed in the design of a building.

All require a learning curve and time to become comfortable with the results - something most of us dread.

You can find the Spreadsheet (aka Multi-Lat) on my website below or on the Structural Engineers International Website at http://www.seaint.org.

If you are interested in the spreadsheet I suggest waiting about a month. The new revised spreadsheet is currently being used in a court case as a tool to verify the accuracy of the initial design. The engineer who is doing the upgrades has been asked not to distribute the revised spreadsheet until the case is over and I suspect this will be in about a month. I don't have any other information to share on this, but have been promised that the upgrade will be available to anyone who wants it.

Finally, this is free-ware. Open source and you may change it as you want. However, you may not profit from the sale of the spreadsheet - only from it's use in your professional practice. If you improve it, we ask that you submit the upgrade back to the professional community for others to benefit from. This is why it was created - for all to use. I like to think of it as "Evolution-ware". I hope  you will help it evolve.

The Structuralist Website:
http://www.structuralist.net
Discussions (BBS and Listservices):
http://www.structuralist.net/lists.htm

RE: Software for Structural Design of Dwelling Houses

Where is this spreadsheet? I visited both mentioned websites and could not find it.

RE: Software for Structural Design of Dwelling Houses

I am not aware of an all inclusive package, and if I found one I would be skeptical without putting it through the paces against hand calc double checks.

For engineered lumber beams I use Trus Joist and Boise Cascade to size lumber .

For dimension lumber and basic 'residential' steel I use Beam Chek.  Most building officials accept Beam Chek output without furhter calculations.  Try www.builderswebsource.com/software/beamchek.

For lateral loading from wind, try Eagle Point software.  They have a suite of software to calculate loads and size members.

The archon website that DaveViking mentioned is a good one also.  Great demos and fair pricing for registered vesions.

RE: Software for Structural Design of Dwelling Houses

Thank you, Gentlemen. The web resources are great. However it appears that I am in over my head.

RE: Software for Structural Design of Dwelling Houses

One new lateral engineering program I just purchased I am very happy with.  It is called LatPro, lateralpro.com is the web site.  I also had the problems structuralist mentioned about being time-consuming to model and work with in both KeyLat and Woodworks.  One caveat so far is that the program uses the simplified method for design and works with only wood-frame structures up to 3-stories in height.

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