Helping with Hospitals

February 8th, 2013

Figure 1: Booms – Seismically anchored mounting supports for overhead hospital equipment. The Image at far right reflects a Boom within strut-supported framing for imaging equipment.

In the hospital construction industry some trends have been developing. Utilizing BIM and IPD in hospital design and construction, all team members are able to coordinate directly and early amongst disciplines, which creates close team collaboration and communication throughout design, planning, and execution. This article will share some things to keep in mind while helping to coordinate above ceilings on hospitals for overhead equipment.

Similar to computer technology, medical equipment becomes obsolete overnight, changes rooms, grows in size, changes manufacturer, and so on. All this information can be tied to the model (room number/equipment number) to help you with future coordination. All of the Boom models and additional miscellaneous steel described in this article were made into groups, with names based on equipment numbers. Cropped 3D views named by room number for quick reference is also helpful. The “individual” Boom groups were also grouped into an “overall” Boom group, making it possible to hide all Booms in framing plans at once. View filters to hide specified family types can also be used.

Figure 2: The left side reflects a “Placeholder” for a Boom. Once the final Boom design is developed, the placeholder “model group” can be exchanged with the actual, which will allow for quick design changes—reflected on the right.

Utilizing Placeholders

Elements that require structure above the ceiling and below the framing should be modeled as soon as possible. For architectural and medical equipment that needs seismic bracing, structural coordination is required. If the exact location and design of a piece of equipment is unknown, you can share what you know with the project team by utilizing a placeholder. This lets the other disciplines on the project team know what rooms will have seismic bracing frames and other elements above the ceiling. Knowing what rooms have these obstructions will be helpful as they lay out early on in the project.

Level of Detail and Development

The placeholder example (Figure 2) would be, for Booms needing (4) kickers, +/-90 degrees from each other in plan. An upside-down pyramid in the general vicinity can be modeled to give the team a heads up that this area will be a "no-fly zone." Your next model will include more information about the Boom Frame; mounting plate size, center of post and size, rod or angle pattern, location relative to the center point, bracing elements, installed mounting heights, access holes, and so on.

Figure 3: Bracing elements (kickers) exactly 45 degrees; but rarely are they installed at exactly that angle. That brace has tolerance of roughly 15 degrees; which can help other disciplines coordinate their elements in the same area which can mitigate clashes in Navisworks.

Mounting plate heights defined in the manufacturers cut sheets and specifications are extremely important to coordinate with the general contractor. The bottom of plate with the designed thickness per the details controls the kicker location. Other disciplines on the project team may need you to adjust kickers the 15 degrees +/- of flexibility, whatever allowed by the structural engineer. To steer clear of any obstruction before it becomes an issue in the field. The next generation of this 3D model verified with the shop drawings. A verified “As-Built” can be captured via LiDAR and/or supplemented with a link to the 3D shop model (if created) and archived for future use or handover at the end of the project.

Figure 4: Imaging Frame made up of strut groups (highlighted in blue) copied as required on center. Groups used in each direction and another for the bridging and rails.

Imaging Frames

Another large above-ceiling structure within a hospital for sliding imaging equipment is called an imaging frame. Here, struts can be located and modeled accurately at the ceiling line, but any mid-height bridging struts will be installed wherever the struts (1-5/8"o.c.) bolt hole lands, closest to center by the installer.

Figure 5: The bridging elements (two perpendicular struts highlighted in blue) are centered (design intent) but will be offset (1) hole up or down to either side of the mid-point / centerline, whatever the specified connector allows.

Figure 6: Modeling “bottom flange bracing” lets everyone know what’s really going on.

Bottom Flange Bracing (aka “Kickers”)

Another important element that can get overlooked while coordinating above ceiling structures is “Bottom Flange Bracing.” I'd like to share a couple modeling techniques that help me place some of these “bottom flange bracing” elements. Always create a “named” Reference plane in plan at the Centerline of where the brace should be placed. Remember to place the reference plane on a reference plane workset, or else others working in your model and linked to your model will be overwhelmed with reference planes. Next, use a view tool that is specific to Autodesk® Revit® Structure called "Framing Elevation." This starts the beginning of the “view range” cut/elevation/section at the grid—or, in this case, the named reference plane to which it is attached. If a sloping steel structure is in view, set the view depth as shallow as possible to not view portions of the structure sloping away.

Next, use the Beam tool, not the Brace tool for this condition. Place the brace angle in plan or elevation to start off and adjust the angle in your framing elevation by adjusting the workpoints to match your detail requirements.

Figure 7: Elevation of “Bottom Flange Bracing.”

Depending on the typical detail/office standard, Bottom Flange Bracing may have a work point 2" above the top of the bottom flange. You may pull out your hair trying to model this accurately in Revit, especially when connecting to sloping structures. For the sloping and or skewed WF Beam it is easy to select the intersection of the top of beam at centerline, but selecting the rest of the edges of the sloping and or skewed WF Beam is nearly impossible—another good place to utilize reference planes!

To locate the kickers at the correct workpoint, utilize a reference plane in section (remembering to put it on the reference plane workset). The bottom workpoint of a sloping or skewed wide flange beam takes the longest to locate. Start off by utilizing “thin lines” to verify accurate start placement (top center).  Start by placing a reference plane down the center of the intersecting beam to locate the workpoint which is the only definable / selectable point on sloping or skewed beam. In elevation, create a horizontal reference plane and copy or move the reference plane down the “beam depth” of the intersecting beam. (See Figure 8 intersecting beam properties) then 2" up, plus the additional thickness of the beam flange (again, see Figure 8 intersecting beam properties).

Figure 8: Select the intersecting beam, open the property of that size (Edit Type) - the Flange Thickness “tf” and Depth “d” are used to locate the workpoint of the bottom flange brace.

Multiple kickers under flat floor framing bay can be copied parallel within a bay. Kickers for sloping structures, typically at the roof, must be created one at a time since the angle of the geometry changes along the slope. There may be a way to do this with a Revit “beam system” if you can define a work point along a given edge, possibly adding a formula to grab the defined beams workpoints +2” +flange thickness… would make this process much faster and easier to manage.

Communicating with Other Disciplines

Something that must happen before everyone starts modeling is the BIM team pre-determines which area of a corridor they'll model/run their main lines. This helps, for when the team tries its hardest to stay within their constraints; it starts the project off a little smoother.

How this relates to Structural is when the SLRS "Seismic Load Resisting System" is adjacent to a corridor. Bottom Flange Bracing is used along the load path (to help with beam rotation along that chord line/collector line/frame) and can kick down through corridors causing unforeseen challenges if not modeled correctly (or even at all). What everyone thought was a big open square tunnel above the flat-framed corridor is actually a smaller triangle shape with sloped framing and bottom flange bracing.

Figure 9: Images above reflect the corridor with MEP shooting through, hanging straps, a compression strut, and bracing. Typically there is much more going on here, but you get the point. The actual corridor may have sloping members and Bottom Flange Bracing. Add fireproofing, sprinklers, pneumatic tube, more disciplines, everyone’s struts and straps, seismic bracing, access for maintenance, metal stud soffit framing with kickers, etc—now we have a problem!

Timing of Revisions Is Crucial

Design changes can be tough to coordinate within Revit when producing prints for post-approval documents. Sometimes more than one package is being worked on/in review/changing/coming in/going out... going backwards? It’s scary. You must carefully plan your work and work your plan.

For local building officials reviewing the documents, it is an administrative code requirement to not work on altered documents that have not been approved or appropriately identified. During CA (the Construction Administration phase), it can be hard to not reflect changes before they're supposed to occur. The model needs to be updated with the “latest and greatest” for the BIM team, but construction documents cannot get ahead of themselves. However you work your magic, be sure to double check your output electronically (PDF, DWF) to verify nothing was changed that was not accepted on the previously approved document, unless it is clouded with delta. I suggest looking into any software that can help you to compare or overlay two structural sheets (PDF, DWF) atop each other. Utilize a QA/QC “Quality Assurance, Quality Control” checklist for the project or from your office. If one is not made, create your own and share with the team—you may find other QA/QC checklists hiding around.

Figure 10: Another example of an above-ceiling obstruction is a seismic support for a sliding partition. Although the rods are spaced closely together, other disciplines will squeeze in between. (Don’t forget to review the shop drawing submittal.)

The CUP (Central Utility Plant) and Miscellaneous Modeled Elements

The CUP includes items such as plumbing, gas, electricity—vital elements for a hospital to run. Typically only the Site Superintendent and the O&M (Operation & Maintenance) team enter this area of the hospital. It contains large equipment needed to keep the hospital operational including additional backup systems in case of a disaster. Visualize seismic restraints and flex connectors gone wild! A coordination nightmare…

Since the O&M staff members are typically the only people working in this area of the hospital, the construction requirements are different. There is a strong possibility that housekeeping pads will be needed for supports (highlighted blue in Figure 11). The entire project team can benefit from you modeling those housekeeping pads and curbs. So instead of using 2D "Detail" line, model those bad boys.

Also helpful is modeling free-standing Pipe support frames, aligned roughly 10 to 20 feet apart. This is worth coordinating together in a big room meeting with the team installing, designing, and modeling the pipes and installing the frame. The option is a bunch of back-n-forth coordination with images and emails, which is not productive and can be time consuming. Utilizing the Internet works, but so does a face-to-face coordination meeting where modelers can update “live and in real time” if you’d like. That might work best here.

Figure 11: New and old CUP joining together. Housekeeping pads highlighted in blue, pipe runs outside and within, heading off towards the main hospital.

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