BBIM Boq Side Formwork | BlenderBim QTO in N menu

S by steverugi on 14 Jan 2024, edited 24 Jun 2024 # +5 votes

using the BlenderBIM N menu allows some nice quantity take-off of building elements, like the side area of a slab, which is not available from the quantity drop-down menu in the Cost Item Quantities pane

Question:

is there any chance to link the output from the N menu into a cost item quantity? (Apart from copy-past it)

I understand it is not standard Qto_SlabBaseQuantities, but it would be handy to have it available

as always, thanks for your kind support

PS as second option the chance to use quantity sets in a formula to calculate it as cost item value, in this case Perimeter * Depth

A by atomkarinca on 24 Jun 2024 # +3 votes

I have a small script that adds a custom Formwork Qto to the file. What it calculates:

for IfcSlab / BASESLAB: perimeter * height
for IfcSlab / FLOOR | LANDING | ROOF: horizontal area - perimeter * height
for IfcColumn / COLUMN: surface area - area * 2
for IfcWall / SOLIDWALL | PARAPET | SHEAR: side area
for IfcBeam / BEAM: (width + height 2) length - (width height) 2

I assume that every beam is connected to a column or a wall on either end, and every slab is surrounded by beams, columns or walls. So if you have beams and slabs that don't conform to these rules you will have deviations. The code is below, I hope this helps.

    from blenderbim.bim.ifc import IfcStore

    import ifcopenshell

    import ifcopenshell.api

    import ifcopenshell.geom

    import ifcopenshell.util.unit

    import ifcopenshell.util.shape



    file = IfcStore.file

    elements = file.by_type("IfcElement")



    unit_scale = ifcopenshell.util.unit.calculate_unit_scale(file)

    net_settings = ifcopenshell.geom.settings()

    net_settings.set(net_settings.DISABLE_OPENING_SUBTRACTIONS, False)



    qtos = ifcopenshell.util.element.get_psets(elements[0], qtos_only = True)

    net_shape = ifcopenshell.geom.create_shape(net_settings, elements[0])



    sub_formwork = 0

    super_formwork = 0



    for element in elements:

        qtos = ifcopenshell.util.element.get_psets(element, qtos_only = True)

        net_shape = ifcopenshell.geom.create_shape(net_settings, element)

        try:

            predefined_type = ifcopenshell.util.element.get_type(element).PredefinedType

        except:

            pass

        if element.is_a() == "IfcSlab" or element.is_a() == "IfcRamp":

            if predefined_type == "BASESLAB":

                surface_area = ifcopenshell.util.shape.get_outer_surface_area(net_shape.geometry) / unit_scale

                sub_formwork = sub_formwork + surface_area

                qto = ifcopenshell.api.run("pset.add_qto", file, product = element, name = "Qto_ReinforcedConcreteQuantities")

                ifcopenshell.api.run("pset.edit_qto", file, qto = qto, properties = {"Formwork": file.createIfcAreaMeasure(round(surface_area, 2))})

            elif element.is_a() == "IfcRamp" or predefined_type == "FLOOR" or predefined_type == "LANDING" or predefined_type == "ROOF":

                area = ifcopenshell.util.shape.get_footprint_area(net_shape.geometry) / unit_scale

                surface_area = ifcopenshell.util.shape.get_outer_surface_area(net_shape.geometry) / unit_scale

                super_formwork = super_formwork + area - surface_area

                qto = ifcopenshell.api.run("pset.add_qto", file, product = element, name = "Qto_ReinforcedConcreteQuantities")

                ifcopenshell.api.run("pset.edit_qto", file, qto = qto, properties = {"Formwork": file.createIfcAreaMeasure(round(area - surface_area, 2))})

        elif element.is_a() == "IfcColumn":

            if predefined_type == "COLUMN":

                surface_area = ifcopenshell.util.shape.get_outer_surface_area(net_shape.geometry) / unit_scale

                area = ifcopenshell.util.shape.get_footprint_area(net_shape.geometry) / unit_scale

                super_formwork = super_formwork + surface_area - area * 2

                qto = ifcopenshell.api.run("pset.add_qto", file, product = element, name = "Qto_ReinforcedConcreteQuantities")

                ifcopenshell.api.run("pset.edit_qto", file, qto = qto, properties = {"Formwork": file.createIfcAreaMeasure(round(surface_area - area * 2, 2))})

        elif element.is_a() == "IfcWall":

            if predefined_type == "SOLIDWALL" or predefined_type == "PARAPET" or predefined_type == "SHEAR":

                side_area = ifcopenshell.util.shape.get_side_area(net_shape.geometry) / unit_scale

                super_formwork = super_formwork + side_area

                qto = ifcopenshell.api.run("pset.add_qto", file, product = element, name = "Qto_ReinforcedConcreteQuantities")

                ifcopenshell.api.run("pset.edit_qto", file, qto = qto, properties = {"Formwork": file.createIfcAreaMeasure(round(side_area, 2))})

        elif element.is_a() == "IfcBeam":

            if predefined_type == "BEAM":

                length = ifcopenshell.util.shape.get_z(net_shape.geometry) / unit_scale

                width = ifcopenshell.util.shape.get_x(net_shape.geometry) / unit_scale

                height = ifcopenshell.util.shape.get_y(net_shape.geometry) / unit_scale

                super_formwork = super_formwork + (width + height * 2) * length - (width * height) * 2

                qto = ifcopenshell.api.run("pset.add_qto", file, product = element, name = "Qto_ReinforcedConcreteQuantities")

                ifcopenshell.api.run("pset.edit_qto", file, qto = qto, properties = {"Formwork": file.createIfcAreaMeasure(round((width + height * 2) * length - (width * height) * 2, 2))})

S by steverugi on 24 Jun 2024 # +1 votes

Hi @atomkarinca

I have a small script that adds a custom Formwork Qto to the file. What it calculates:

for IfcSlab / BASESLAB: perimeter * height

for IfcSlab / FLOOR | LANDING | ROOF: horizontal area - perimeter * height

for IfcColumn / COLUMN: surface area - area * 2

for IfcWall / SOLIDWALL | PARAPET | SHEAR: side area

for IfcBeam / BEAM: (width + height 2) length - (width height) 2

I assume that every beam is connected to a column or a wall on either end, and every slab is surrounded by beams, columns or walls. So if you have beams and slabs that don't conform to these rules you will have deviations. The code is below, I hope this helps.

Amazing stuff!, your code does help me just right, incidentally these days I am trying to learn how to use the util API to improve my workflow (and understand ifcopenshell and IFC a bit more in depth), I just finished with util.cost which I found very useful for handling QTO data.

many thanks for your help

E by emiliotasso on 24 Jun 2024 #

@atomkarinca great works!

for IfcSlab / FLOOR | LANDING | ROOF: horizontal area - perimeter * height

in the formula above horizontal area is only one face or two (bottom and up?)

usually slabs have only formworks on the bottom side.

Thank you, your script is very useful

E by emiliotasso on 24 Jun 2024 # +1 votes

Some time ago, following the very interesting job that @steverugi has made with quantity calculations i was thinking about formwork costing.

So I've thought that the net area for concrete element covered by formwork maybe can be extrapolated using clash detection algoritm in order to evaluate the free surface of the objects

S by steverugi on 24 Jun 2024, edited 24 Jun 2024 # +2 votes

hi @emiliotasso

@atomkarinca great works!

for IfcSlab / FLOOR | LANDING | ROOF: horizontal area - perimeter * height

in the formula above horizontal area is only one face or two (bottom and up?)

usually slabs have only formworks on the bottom side.

Thank you, your script is very useful

good point, I've yet to go through the script in details

my personal take on formwork quantities:

slabs depends on how you consider the RC frame, I normally see them framed inside beams and column tops, unless they are balconies or landings. In the first case only the soffit (i.e. the bottom side area) is considered, otherwise external faces too.
beams differ if external or internal due to slab thickness, both sides and soffit with adjustments due to different colum sides/orientation
columns are usually perimeter * length with deduction for beam height or similar

formork quantity calculation is, in my view a nasty business, currently I prefer to use IfcCovering and go with relevant area, tbh it's faster if you have basic modeling skills

ciao

A by atomkarinca on 24 Jun 2024 # +2 votes

@emiliotasso said:

@atomkarinca great works!

for IfcSlab / FLOOR | LANDING | ROOF: horizontal area - perimeter * height

in the formula above horizontal area is only one face or two (bottom and up?)

usually slabs have only formworks on the bottom side.

Thank you, your script is very useful

In my original post I mentioned that I assume that slabs are surrounded by columns, beams or walls. In this scenario I would like to deduct the amount of formwork resulting from this connection, because the connected elements have less formwork resulting from this.