Losing Weight With Advance Steel

Having used Advance Steel to model your structure in 3D you would expect to be able to find the weights of things. You certainly can, but there are a number of details to consider if you want to get accurate answers. For example, in the image above there are 3 different weights provided by the two weight commands. Which is correct 8100kg, 5607.60kg or 5357.60kg?

Assembly Weight Information

Found on the slide out of the Home > Checking ribbon panel this command tells you the weight of everything in the selected assembly(s) when you pick just one object in each. So if you just easily select the hand rail in a railing the entire weight of everything connected in the workshop in that railing is provided. No need for fiddly selection of each component. This function gives TWO answers though. What is that all about?

The first answer, “Assembly weight” (yellow in the image above), is an approximate answer. This uses different methods to calculate the weight of plates depending on the setting of a default – see below. For beams it calculates the weight of the beam including any shortens but ignores any other features on the beam. Bolts holes are ignored for beams and plates. Hence this answer will always be the highest of the possible answers.

The other answer is “Assembly Exact weight” (green in the image). As the name suggests this is an exact answer; accurately calculating the net shape of the members including all holes etc and including special parts. This is the most accurate answer you can get from the system.

Centre of Gravity and Total Weight Calculation

The other command that gives you a weight is Home > Checking > Centre of Gravity and total weight calculation (blue answer in the image). This works differently to the Assembly Weight calculation in several ways. This literally only gives a weight for the objects you select so you must be sure to select everything in each assembly. This command always uses the exact net shape of the objects to calculate the weight without worrying about any defaults. However, regardless of whether you select them or not Special Parts, Bolts, Anchors and Shear Studs are never included so your results can be quite inaccurate.

Centre of Gravity

Since Special parts, fasteners and welds are not included in this calculation the position of the C of G provided may be inaccurate if a non-symmetrical arrangement of these objects is included in your selection.

As a side note, you can type the command PTYPE into the AS / AutoCAD command line to choose which symbol is used to mark the C of G in your model so it is visible.

Plate Default

In the Management Tools > Defaults under Plate > General is one called “Calculation Rule for the area”. This has four options. “Smallest circumscribing rectangle” gives an area and weight based on a simple rectangular plate regardless of all cuts and features. “With inner contours” calculates the results from the correct net shape of the plate with all holes and features considered. The tooltip image gives illustrations of the four settings. I would suggest it is best to use “with inner contours” for most things.

Special Parts

When you insert a special part there is weight property on the first page of the properties. It is important that you fill this in as the system cannot calculate the weight of the part based on its volume. This is because the one solid inserted may represent a complex assembly with spaces and varying materials. If you don’t add the correct weight value in the property yourself all your results will be incorrect.

Bolts, Anchors and Shear Studs

Unfortunately, these are never included in the two commands above. The only way to get the weight of these is to select the relevant parts in the model then use BOMs such as the “UK Bolt and Anchor List” to show the weight of the related fasteners. Fasteners are considered to belong to the part the head of the bolt or anchor sits on.

Bills of Materials

There are many different tokens for weights to use in Bills of Materials. These include ones for both approximate weight (they just say “Weight”) and Exact Weight (which say “Exact Weight”). If the weight is important to you, check which token is being used in your preferred BOM.

As you can see, depending on which answer you take and what setting you have it is easy to lose a couple of hundred pounds with Advance Steel ?. Ultimately, whether you want to use the Weight or Exact Weight results is up to you and likely depends on the circumstances, but it is important to understand the points above to ensure the answer is suitably accurate for your needs. The table above summarises what is or is not considered for each.

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