BIM Workfows: Scoping by Space Adjacencies

Doing a pretty tedious exercise at the moment.

The contractor would like to change the wall build-ups which means that all the performance criteria for each wall needs to be re-evaluated... for each wall, individually.

The list of criteria includes: fire, thermal/condensation risk, airtightness, lateral / barrier loading, vertical loading, security etc etc. I won't mention the additional client-specific requirements, just the direct/in-direct building regs-related ones.

BIM models mean including and attaching a lot of information to the 'building objects' like walls. All nice and efficient and ready for all those fancy-pants data mining and machine learning presentations... but it all needs to be manually cross-checked and input'd. This is of course the weak link. GI-GO. Especially when changes are made under site conditions.

For defining the performance criteria for walls, a lot is dependent on the adjacency of the Spaces that the wall sits between.

1. Fire:

a. Shafts: 2hrs

b. Rooms with special fire risks: 1-2hrs

c. Escape routes-generally- 30mins (min).

d. Intervention routes: 2hrs

2. Thermal:

a. External walls

b. Plant rooms with temperature sensitive equipment

c. Heated spaces

d. Walls between heated spaces: no insulation.

3. Condensation:

a. High humidity rooms (Showers, kitchens)

b. Roof spaces

c. Semi-external spaces

4. Airtightness:

a. External spaces

b. Heated spaces

c. Pressurised escape routes

d. Buildersworks ducts and plenums

5. Lateral loading:

a. External:- wind loading

b. Public areas: crowd loading

c. Next to voids: crowd loading

d. Trolley traffic, service corridors

6. Vertical loading:

a. Clad-walls (dependent of type/weight of cladding)

b. MEP rooms, risers

c. Shelving, benching, sanitary fittings

7. Security:

a. Public/staff-only boundaries.

b. Critical rooms, ATM enclosures, risers.

8. Acoustics:

a. By room type, NR or STI level ratings.

b. MEP spaces with noisy plant.

I wonder if ABD's Spaces shouldn't be used to help with ensuring consistency, compliance and ultimately the quality of the information in the BIM model.

  • A Wall object should be able to query the Spaces on either side based on some rules. For example, if a Wall abuts a Space defined as an escape shaft, then it should have a specified fire rating. If it is defined as an external wall (defined as part of the AES model?) then it should have a specified thermal U-value performance. Etc etc. This kind of adjacency checking would enable 1, 2, 3, 4, 5, 8 quite easily, based on the information that would already need to be inputted into the Spaces, as part of the space planning and brief-taking process. Sweep line algo? Proximity testing algo? GPU?

  • Some criteria like 5(d) would need additional information to be added to the Space 'schema' or list of attributes, or via an additional 3d Solid, Shape, or Smartline that would define the circulation routes that would be subject to trolley impact loads. Security boundaries could be modeled as volumes that define lines of control, and essential routes. The new Constraints tools would allow the user to minimise manual updates by geometrically linking them to existing Spaces. ABD/ConstructSIm already has a means of selecting objects within the boundary of a Space. This would be useful in combination with the new Schedules/DGExplorer tool, which should allow bulk adding of security attributes to objects or Spaces within a volume.

  • Checking/defining the vertical loading on walls would be greatly enabled by the ability to sense and query adjacent objects like cladding, shelving, signage, FFE items, MEP ducts etc. A run of blockwork backing wall may span across mulitple cladding types. It would be useful to be able to highlight and collate the different cladding types (rainscreen, tiles, render etc) and the objects that are abutting or within the wall (like doors) using some kind of 'soft clash' or interference tool. Some kind of link back to the structural engineer's loading plans / model would also be dreamy.

  • What happens when a Wall has multiple requirements along its length or height? I think ConstructSim has a means of 'layering' this information on in a 'non-destructive' way. Structural elements like slabs are modeled 'whole' and need to be split up to suit the construction sequencing. It is important not to over burden the BIM model, and support 'federating' information.

Walls are only one type of object. It would be good to have a reasonably robust geometry-based query tool that would be able to sense and query what is above/below in addition to what is on either side of a linear element like a wall or beam etc. What is inside or outside relative to a volume, normals, intersections, separation distance (like Bentley Map/ArcGIS buffers) from another object or Space or datum woulld also be very useful.

One thing that will be useful for ABD's schema for all its objects is allow the user or the placement tool to define and store 'connectivity' information with the object. A shelf object placed on a wall should have a 'Mounted on' relationship attribute. This could follow the approach Design++/PlantWise uses, where each object has a bounding box that top, bottom, side faces. Mstn elements already has this bounding box info but D++ goes one small -but important- step further by giving these faces a semantic dimension. Linear objects have an axis, Components or Cells can have mating points. This allows some very powerful aligning and query functions like 'Mounted On' to take place. Also more breadcrumbs for HUD dimension tools to leverage?

Rules: the aligning and query functions would be implemented using rules.. which is much more flexible and robust compared to imperative scripted relationships, or history/feature-based parametrics. If a Shelf has a relationship attribute like 'Mounted_On' and a pointer or ElementID to a Wall, there would be enough information to provide more usable smart 'parametric' behaviour to the user. The user may want to move the wall first and satisfy himself that it in the desired location before moving the hosted elements. This kind of 'get' behaviour is much better than the 'put' behaviour that you get with most parametric modelers where the constraints/relationships are pre-defined by others, and very difficult to manage and not very scalable.

The 'I' in BIM should not only be about tagging elements with the boring 'business info' associated with the FM-biased BIM processes that we tend to hear about today. There needs to be more done about defining and querying relationships between objects.... which is key to BIM info producers like architects and engineers. The BIM model consumers will also benefit, I am sure.

Parents
  • Update: removing the insulation is some of the rooms triggered the need to update the wall thermal / vapour permeability properties in the Hevacomp model. This unfortunately had to be updated by manually! It would be great when Hevacomp gets subsumed into AES. The wall buildup would also then need to be check for condensation risk in Hevacomp. It would be a great help to have a close synch between ABD <> AES so minimise abortive work, errors and labour.

    The other function the wall insulation has is acoustic attenuation. As mentioned elsewhere, it would be good to have AES include an acoustic model, based on the noise levels generated by the MEP kit and other emitters. I see a lot of acoustic engineers making guesses or doing things manually... not sure if there is anything on the market that does this. Hint hint!

    Large infrastructure jobs are usually subject to a level of compliance checking that would be unaffordable in the commercial sector... leading to increased costs and documentation requirements. Having a digital model would be a way to claw back some profitability. Digitalisation would also pave the way to a finer level of engineering quality by allowing more and quicker iteration cycles, especially upfront where the impact would be greatest but the budget the smallest.

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  • Update: removing the insulation is some of the rooms triggered the need to update the wall thermal / vapour permeability properties in the Hevacomp model. This unfortunately had to be updated by manually! It would be great when Hevacomp gets subsumed into AES. The wall buildup would also then need to be check for condensation risk in Hevacomp. It would be a great help to have a close synch between ABD <> AES so minimise abortive work, errors and labour.

    The other function the wall insulation has is acoustic attenuation. As mentioned elsewhere, it would be good to have AES include an acoustic model, based on the noise levels generated by the MEP kit and other emitters. I see a lot of acoustic engineers making guesses or doing things manually... not sure if there is anything on the market that does this. Hint hint!

    Large infrastructure jobs are usually subject to a level of compliance checking that would be unaffordable in the commercial sector... leading to increased costs and documentation requirements. Having a digital model would be a way to claw back some profitability. Digitalisation would also pave the way to a finer level of engineering quality by allowing more and quicker iteration cycles, especially upfront where the impact would be greatest but the budget the smallest.

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