Mission Impossible

Meet the seven Autodeskers who rocked Nepal, as I like to call the team of volunteers who have created an amazing tool to retrofit buildings.
Revit Structure and Dynamo were the two powerful tools that made this happen.
I, a civil engineer and a Revit Structure QA Analyst, together with six colleagues from Autodesk went to Nepal to begin a journey that seemed impossible.

We came from different parts of the world (San Francisco, Chicago, Boston, Bucharest, and Singapore) with different backgrounds (UX Architect, UX Designer, Software Architect, Technical Support Specialist, QA Analyst, and Emerging Territory Sales Executive). We were supported by a great team from Team4Tech and Build Change on the ground.

The challenge is huge. Hundreds of thousands of buildings were damaged after Nepal was hit by two major earthquakes in 2015 (April 25th Mw 7.8 and May 12th Mw 7.3). More than 50% of the buildings did not collapse, but were unsafe because the structural resistance was weakened.

Up until now, the Nepali government and various charity organizations created a process to help affected homeowners build a new disaster-resistant house. Due to budget limits, these new houses are much smaller than the original they replace. The International NGO Build Change is an Autodesk Foundation grantee that designs disaster-resistant houses and schools in emerging nations and trains builders, homeowners, and government officials to build them. There’s an article about this on Build Change’s blog here.
Build Change engineers in Nepal created a new retrofitting method that can make existing houses resistant to earthquakes. They experimented with three prototypes — a light, a medium and heavy retrofitting solution.
While retrofitting an existing building is significantly less expensive than building a new house, it requires custom instructions for each case. Until now, there was no viable way of creating these instructions at a large enough scale. Build Change reached the Autodesk Foundation and the Nepali Government for help to make the retrofit idea a viable alternative to new construction.
So our team flew to Nepal for 13 days to understand the problem, come up with a solution, and design a new “tool” to help Build Change and the Nepali engineers get retrofitting to scale. It felt a bit like mission impossible …

Revit, Collaboration4Revit, Dynamo and Human Centered Design to the Rescue

Once we landed in Kathmandu, our goals were to:

  • Learn directly from the field engineers and architects what it takes to retrofit a house
  • Use Human Centered Design and LUMA methods to understand the relationship between key workflows and local stakeholders (Government, house owners, NGO’s, engineers)
  • Prototype solutions to the retrofit challenge
  • Provide documentation for Build Change to use once we had returned home
    It was a lot to deliver in two weeks. We knew we had to automate the retrofit process, and we decided that the idea of creating a rule-checking tool using Dynamo and Revit would not only save a lot of time but could make the process as accurate as an engineer would have.

Solution – Template Model

Most of the houses in Nepal have a rectangular shape, and are between 1.5 and 2.5 stories with different openings, different story height and different plaster. This simplified our task.

We quickly decided that the core strength of Revit’s parametric model will be a perfect match for the desired automation. Rather than starting retrofit instructions for a house from a blank sheet, the engineer can use a 3D template model that is already set up with all the necessary components. In fact, the template model can be carefully set up to be adaptable to a lot of typical conditions.

Once we agreed to this template approach, we jumped in to making the model plus writing the tools to check the seismic requirements.

We had only four days left at this point…

Huddled around a table with our laptops in a hotel room in Kathmandu, we set up a Collaboration for Revit (C4R) project to allow each of us to modify the model at the same time, pinned a large sticky poster on the wall to manage the list of tiny tasks and started pounding our keyboards…

Dynamo scripts + measuring Revit families

Mark Sinclair, the Build Change engineer behind the retrofit method, explained us all the necessary details of what makes a house earthquake resistant. With his help, we identified three main aspects of the model that must be checked to make sure the house will be strong enough to withstand the next earthquake. The three aspects were:

  • Wall Opening Check
    o Total width of openings on a given wall cannot exceed a fixed percentage relative to the length of the wall. This depends on the type of wall construction.
  • Pier Width Check
    o On a façade wall, the “piers” between windows, doors, wall ends should not be too skinny to withstand forces that try to tilt the wall along its length.
  • Strong Back Placement Check
    o Special columns (strong backs) need to be placed along the inside of the perimeter walls. They are tied to the walls and connected at top by a concrete perimeter “ring”. They cannot be too far apart to effectively support the walls from falling out if the forces act transversally (“out of-plane”).

Rather than trying to implement a fully automatic solution where the computer would attempt to make changes to the model to satisfy these requirements, we decided on a simple, yet powerful approach:

The user of our “tool” will place specially prepared measuring components and run simple Dynamo scripts that analyze those components relative to the model. The component turns green or red to indicate if the check passes.

This simple idea of using measuring families has multiple benefits:

  • We avoid the complexity of a fully-autonomous solution
  • It is easy to tweak what the user wants to measure
  • The measuring objects (lines, rectangles) can be added to the template model to speed up adaption of the template to the next house design
  • The result of checks leave a human readable proof that can be printed, stamped and verified
  • It is easy to teach inexperienced Revit users to run the checks
  • Can be deployed immediately and can be automated later

 

Wall Opening Check

Pier Width Check

Strong back Placement Check

The Dynamo scripts simply scan the model to find the measuring components, extract the necessary parameters and geometries from the model, do the simple calculations and set the results of the check as parameter values to the measuring components back to the model.

The model has special measuring views set up with view filters to color the appropriate components red if the test did not pass simply based on the value of the parameter that was set by the script.

In the end, the user has the following workflow to design the retrofit:

  1. Adjust the template model to match the shape of the given house.
  2. Place measuring lines for wall openings in the Opening Check views
  3. Place Pier Width checking rectangles on the façade views.
  4. Place strong backs where it is intuitively needed.
  5. Run the three scripts using Dynamo Player
  6. Inspect the views for red (failing) conditions
  7. Make simple adjustments to the model and check until everything is green.
  8. Print retrofit instructions for approval

These simple steps do not require expert knowledge of Revit yet allow full flexibility to create a design.

Our goal was to create a tool that is scalable to thousands of designs. Since our departure, Build Change took our template and further refined the models. In the early trials, two engineers could create 16 retrofit designs on a single day!

We were proud to deliver a tool that is easy to use and saves a lot of time. We presented out findings on the last day in Nepal to an audience of Build Change staff, and representatives from local government and NGOs. We know that the tool will help these groups reach more homeowners and create new momentum for rebuilding in Nepal.

Build Change continues to train their staff in Autodesk software and our new retrofit tool. They are also teaching thousands of local government officials how the tool works in order to expedite the retrofit approval process for thousands of homes across the country. Build Change will continue to develop this tool, with the support of the Autodesk Foundation, with the goal of customizing it to new house types in Columbia, Haiti, and more.