[How to] Create a custom Qto calculation

S by steverugi on 5 Nov 2024, edited 5 Nov 2024 #

@Dimitris

@steverugi said:

@Dimitris

Quick question if it hasn't been already answered. How can you change the precision in BONSAI to have more than 3 decimals for the calculation of multiplications (at the moment it only supports 2 in my case but I cannot find where I can change that)?

can you please show where you perform such calculation? thanks

So taking from the example above the

19931 Labor Assembly Construction service worker cat.3 hr 0.003

has 0.003 hrs of usage but if you place that value in the resource base quantity

thee result will be a 0

and by updating the resource in the cost schedule:

the result is again 0

OK, thanks for the reply, I think it's a bug needed to be posted on issues

..or work it out per Tonne instead of Kg to pump up your ratios ;)

D by Dimitris on 5 Nov 2024 #

@steverugi said:

@Dimitris

@steverugi said:

@Dimitris

Quick question if it hasn't been already answered. How can you change the precision in BONSAI to have more than 3 decimals for the calculation of multiplications (at the moment it only supports 2 in my case but I cannot find where I can change that)?

can you please show where you perform such calculation? thanks

So taking from the example above the

19931 Labor Assembly Construction service worker cat.3 hr 0.003

has 0.003 hrs of usage but if you place that value in the resource base quantity

thee result will be a 0

and by updating the resource in the cost schedule:

the result is again 0

OK, thanks for the reply, I think it's a bug needed to be posted on issues

..or work it out per Tonne instead of Kg to pump up your ratios ;)

Thank you @steverugi,

Shall I proceed with the posting in the issues?

I would prefer of resolving the decimal issue rather than modifying standardized "Rated Built up" items

S by steverugi on 5 Nov 2024 #

@Dimitris

Thank you @steverugi,

Shall I proceed with the posting in the issues?

I would prefer of resolving the decimal issue rather than modifying standardized "Rated Built up" items

yes, it would be helpful

apart from decimal places, were you able to get your resource based rate build-up working?

D by Dimitris on 5 Nov 2024 #

@steverugi said:

@Dimitris

Thank you @steverugi,

Shall I proceed with the posting in the issues?

I would prefer of resolving the decimal issue rather than modifying standardized "Rated Built up" items

yes, it would be helpful

apart from decimal places, were you able to get your resource based rate build-up working?

Thanks @steverugi

Yes I have used the sum function and now it gets all represented as a single value, although I do not know further down the road when you want a break down of costs by resource, or break down of resource quantities if this will be achievable by using this grouping method.

S by steverugi on 5 Nov 2024, edited 5 Nov 2024 # +1 votes

@Dimitris

Yes I have used the sum function and now it gets all represented as a single value, although I do not know further down the road when you want a break down of costs by resource, or break down of resource quantities if this will be achievable by using this grouping method.

Interesting topic, as I posted earlier many things can be sorted out in a different environment

I love Bonsai but I can't see it suitable at the moment as a complete tool for quantity surveying, especially when further calculations are needed along with preparation of schedules ready for publication.

In my opinion and experience Bonsai is the perfect tool for quantity extraction for both .ifc model or 2D dwg to be converted into one.

I find Spreadsheet Import/Export in Quality and Coordination > Collaboration the most useful (and flexible) feature to do so, leaving to the BoQ the role of assigning classification and, when possible, cost items from a schedule of rates, so that all info can be contained into a single .ifc file, documentation reference included.

Exporting .csv tables allows further manipulation in PowerQuery or Pandas and I see no problem with it, after all learning how to use selector_syntax along with Regex and a bit of Python/Pandas is something you want to have anyway nowadays, what do you think?

D by Dimitris on 5 Nov 2024 # +4 votes

@steverugi said:

@Dimitris

Yes I have used the sum function and now it gets all represented as a single value, although I do not know further down the road when you want a break down of costs by resource, or break down of resource quantities if this will be achievable by using this grouping method.

Interesting topic, as I posted earlier many things can be sorted out in a different environment

I love Bonsai but I can't see it suitable at the moment as a complete tool for quantity surveying, especially when further calculations are needed along with preparation of schedules ready for publication.

In my opinion and experience Bonsai is the perfect tool for quantity extraction for both .ifc model or 2D dwg to be converted into one.

I find Spreadsheet Import/Export in Quality and Coordination > Collaboration the most useful (and flexible) feature to do so, leaving to the BoQ the role of assigning classification and, when possible, cost items from a schedule of rates, so that all info can be contained into a single .ifc file, documentation reference included.

Exporting .csv tables allow further manipulation in PowerQuery or Pandas and I see no problem with it, after all learning how to use selector_syntax along with Regex and a bit of Python/Pandas is something you want to have anyway nowadays, what do you think?

Couldn't agree more, adding that I want to see it also as a 4D&5D combined tool. And yes there is a lot to cover but from what I can see this discussion has been very valuable to the community of QS and PM for that reason. Giving chips of insights and tips FROM the community TO the community.

P.S. Posted issue. Would be great if GIT had an upvote feature for issues

M by Massimo on 4 Jan 2025 # +4 votes

I have managed to add a section on wiki about how to create custom ruleset in bonsai

https://wiki.osarch.org/index.php?title=BlenderBIM_Add-on/Bonsai_QuantityTakeoff

Feel free to improve it, cheers

D by Dimitris on 4 Jan 2025 # +1 votes

Hi Massimo great article on wikki.

May I suggest the following as a more standardised way of using the qto based on existing IFC Pset properties

For elements as slabs beams columns etc that are structural elements we can Use the Pset_ConcreteElementGeneral to populate the ReinforcementAreaRatio and as such keep it as much as posssible within the existing standardised properties of the schema. If I am not mistaken, the variable Beam Rebar Weight that you are using in your example should be substituted by ReinforcementAreaRatio in the /ifc5d/qto.py file, right?

Let me know what you think

Cheers,

M by Massimo on 4 Jan 2025, edited 4 Jan 2025 #

Well @Dimitris i think that using the standard pset value (if available) is of course better.

Also, the ReinforcementAreaRatio seems to me that has a different meaning with Beam Rebar Weight (reinforcement area ratio is a ratio between steel area and concrete area, beam rebar weight is the steel weight).

D by Dimitris on 4 Jan 2025 # +1 votes

@Massimo said:

Well @Dimitris i think that using the standard pset value (if available) is of course better.

Also, the ReinforcementAreaRatio seems to me that has a different meaning with Beam Rebar Weight (reinforcement area ratio is a ratio between steel area and concrete area, beam rebar weight is the steel weight).

You are right, apologies for the miss, kindly use ReinforcementVolumeRatio

Thank you for pointing,

M by Massimo on 4 Jan 2025 # +1 votes

Of course it is possible also to use an object pset property to perform the calculation so ReinforcementVolumeRatio could be used instead of the coefficient described in the article

S by steverugi on 4 Jan 2025 #

@Dimitris

You are right, apologies for the miss, kindly use ReinforcementVolumeRatio

Thank you for pointing,

In my experience sometimes slabs have a kg/m2 since area is the unit of that work, but not always.

As you and @Massimo indicated beams and columns have kg/m3 ratio

I'm very happy about this feature

Thanks

D by Dimitris on 4 Jan 2025 #

@steverugi said:

@Dimitris

You are right, apologies for the miss, kindly use ReinforcementVolumeRatio

Thank you for pointing,

In my experience sometimes slabs have a kg/m2 since area is the unit of that work, but not always.

As you and @Massimo indicated beams and columns have kg/m3 ratio

I'm very happy about this feature

Thanks

Hi @steverugi ,

I've come across this concept of Kgr/m2 mostly for load bearing screeds and non structural concrete platforms (subbase etc), haven't come across a BoQ in which the Structural Elements where quoted as Kgr/m2 .

S by steverugi on 5 Jan 2025 #

sure @Dimitris, methods also change based on their locale , concrete slab on grade here in Ghana sometimes has just a single or double mesh, which typically has a kg/m2 weight, and the steel/concrete ratio follows accordingly.

However, what is important to me is @Massimo 's method that, while waiting for future new implementations in the UI, it allows users to create custom calculations, which are much needed in the quantity take-off daily routine, at least in my experience.

cheers