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# Why buy Merlin Dash when we have NSBA's Simon

## Why buy Merlin Dash when we have NSBA's Simon

(OP)
Hi,

I wanted your opinion on why would someone/a company would buy Merlin dash when we have Simon by NSBA, both will perform an analysis for straight steel bridges, heck Simon will even do box girders, so why buy Merlin Dash ?

Thanks,

### RE: Why buy Merlin Dash when we have NSBA's Simon

My state DOT tested Simon and found it unreliable. We won’t use it, or let consultants.

### RE: Why buy Merlin Dash when we have NSBA's Simon

My understanding is that Simon is for Preliminary Design. It nly does line girder analysis; then again, in many cases that's all you need.

I used it a couple of years ago to determine dead load deflections for a staged deck pour for a rehab project. At the time MDX couldn't directly handle staged construction. When I compared the results from Simon, MDX, and the original drawings (the original deck was placed fascia to fascia) there were points where all three matched. Generally, MDX and Simon gave similar results. Does that mean both programs are reliable, who knows? All I know is the deck closed.

TheRick109 - just curious, what in particular was wrong with Simon? I'm not into modeling; I leave that to the young people. Although I find at times, we get weird results from CSIBridge.

### RE: Why buy Merlin Dash when we have NSBA's Simon

(OP)
Thanks Bridgebuster, we usually Use MIDAS for complex modeling but for line girder analysis we use Merlin Dash which is a very good, light software, but just watched a webinar that kind of promotes SIMON and I was interested in seeing what people think of it.

TheRick109, am also interested in knowing what was wrong with SIMON and when ? , as we all know, these things get updated regularly

Thanks All

### RE: Why buy Merlin Dash when we have NSBA's Simon

Bride_man - we tested it 4 or 5 years ago. The software didn’t perform a lot of basic design checks. I’m sure you’ve heard the saying “you get what you pay for”. NSBA is also sponsored by fabricators, when I tested the splice program I found instances where you needed more steel on the main members. Again, driven by fabricators so go figure.

I’ve used Merlin Dash for 15 years. It’s great for straight steel girders. Dr. Fu at the University of Maryland always responds to questions as well - if he’s still there.

### RE: Why buy Merlin Dash when we have NSBA's Simon

I am not familiar with either program, but I thought the following statement from the NSBA site was interesting:

#### Quote (NSBA)

LRFD Simon is a powerful line-girder analysis and preliminary design program for steel I-shaped plate girders and multiple single-cell box girders. It allows users to quickly produce complete steel superstructure designs in accordance with the 8th Edition AASHTO LRFD Bridge Design Specifications. The program is offered free of charge by the National Steel Bridge Alliance (NSBA).

My emphasis.

So is it for preliminary design or complete superstructure design?

Either way, having an independent program to check the results is reason enough to buy a commercial package.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

### RE: Why buy Merlin Dash when we have NSBA's Simon

Bridge Man,

I have nothing useful to add to the Merlin vs Simon discussion, but I noticed that you mentioned Midas (I'm assuming Civil). I also use Midas. For awhile, it seemed that no one used it but it does seem to have been gaining a lot of traction lately.

### RE: Why buy Merlin Dash when we have NSBA's Simon

I found Midas to be extremely un-user friendly, probably the worst bridge engineering software I ever tested. I advised against purchasing it and we went with CSI instead. Both of these 3D programs are unnecessary for simple straight I-beam bridges. A lot of consultants use MDX because it can do straight and sweeped (curved) girders, but the amount of errors in that program have caused some to move away from it. As someone that is familiar with:

Merlin Dash
MDX
Midas
CSI
Simon
Virtis/Opis - AKA BrDr now

Merlin Dash would be my first choice.

### RE: Why buy Merlin Dash when we have NSBA's Simon

(OP)
Great Stuff guys, Thanks to all. Also Merlin Dash allows for load rating which is nice.

Regarding Midas Civil, Yes. to tell you the truth I started to love the software, I have used CSI Bridge in the past and now using MIDAS civil, each software has merit over the other , but I kind of like the unfriendly user interface TheRick109 is talking about, I like having tables for every element am dealing with, making overwriting stuff much easier.

Thanks all

### RE: Why buy Merlin Dash when we have NSBA's Simon

#### Quote (TheRick109)

I found Midas to be extremely un-user friendly, probably the worst bridge engineering software I ever tested. I advised against purchasing it and we went with CSI instead.

Interesting. I'll admit that the learning curve was sort of steep, albeit lower than Lusas, I became quite proficient with it. My understanding with CSI Bridge was that it is heavily wizard based and tries to fit all designs into nice little boxes to help save on modeling time. Using it as a general FEA or for something that is unique is not its forte. I like Midas Civil since I can either use their wizards (which I rarely ever do) or create my own custom bridge layout. This makes it very convenient for load rating/designing bridges with odd geometric shapes. Well, to each their own...

I feel a bit embarrassed bringing this up but does no one use BRASS Girder? I usually always run a BRASS check on my design to verify that I didn't miss something. It's not fancy or elegant but it is really good at crunching time consuming AASHTO code checks for straight girder bridges.

### RE: Why buy Merlin Dash when we have NSBA's Simon

STrctPono - maybe Midas has changed, but I also recall that the program didn't know if the beam was in negative flexure or not. I haven't looked at the program in 5 years or more, but at the time it looked like something build based on a Microsoft Access programming or something.

BRASS girder was kind of discontinued as an engine in Virtis/Opis or BrDr once AASHTOware came into play. Also, and not to step on BridgeSmith's toes, but I believe BRASS was developing by the Wyoming DOT and was limited to flange widths of 20" or so because at the time Wyoming had no flanges wider than that. In the Northeast, we have some pretty large bridges that BRASS couldn't handle.

BrDr is also terrible, but a lot of the state DOTs require it. The GUI is based on mid-1990 technology. There is a revitalization effort going on, but by the time the states finish it we will all be flying around in spaceships not needing bridges anymore.

### RE: Why buy Merlin Dash when we have NSBA's Simon

In the 90's we used Merlin Dash, I found it very easy to use. Before 2000 we went to MDX because we needed something with curved girder capability. However, to me and as TheRick109 said, it always seemed to be fraught with errors. It couldn't easily do deflections for staged construction. A majority of the younger people in the office seem to prefer CSI.

Has anyone used LUSAS? I get emails from them regularly about a free demonstration of their product.

### RE: Why buy Merlin Dash when we have NSBA's Simon

(OP)
Bridgebuster,

I wouldn't use CSI or MIDAS for a straight bridge line girder analysis, its a waste of time, I use merlin for such cases.

Same story with Lusas , a lot of e-mails but never tried it

### RE: Why buy Merlin Dash when we have NSBA's Simon

Our office uses both Lusas Bridge and Midas Civil. Due to its cost, we only have 1 Lusas key which 4 of us Engineers had to share. Since that setup just wasn't practical, we ended up picking up 2 Midas (cheaper) licenses. I think we pay something close to $30,000 -$40,000 for Lusas every year. That comes with support and the full non-linear package. Honestly, it's a very powerful program. My personal belief and I think there would be many others who agree with me in the bridge community..... Lusas is the gold standard for FEA programs in the bridge world. For almost all seismic analysis, we have 2 Engineers running simultaneous analysis (1 Midas and 1 Lusas). None of us use the programs for design but rather for pure analysis. In general we rarely have discrepancies with the outputs. Lusas does seem to have additional features that Midas does not. Lusas is also a much steeper learning curve for use.

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