Today's medical equipment is a significant investment and a critical component of a healthcare project-it can account for up to 50% of the first cost of today's healthcare facility and generates much of the life cycle revenue. In extreme cases, the cost of equipment housed within a structure can exceed the construction cost of the building.
With heavy weights, strict vibration-control requirements, and the need for protective radiation shielding, this considerable asset has a significant impact on, and greatly relies on, the structural system's design. The cost of not properly planning early in design for the structural systems for healthcare equipment is high.
To meet the challenges of supporting medical equipment, structural engineers have considerations ranging from the truly weighty to the extremely narrow:
The magnet in each magnetic resonance imaging (MRI) unit weighs about the same as a typical yellow school bus filled with a varsity football team. The floor must support this weight in a smaller footprint.
The required protective radiation shielding of a linear accelerator vault can weigh as much as a 20-foot-deep swimming pool and can take up four to eight feet of solid concrete floor depth.
Operating room microscopes are so sensitive to vibration that the structure is commonly required to move less than the width of a human hair in a second.
Although these examples seem extraordinary, they represent only a fraction of the unique challenges of supporting medical equipment. Without proper planning for equipment's impact on the structural system, the results can limit function. For example, deep structural elements limit plenum space, closely spaced columns prevent an efficient architectural layout, and downstream strengthening of a structural element can impact use of space on adjacent floors. The architect, equipment planner, and structural engineer must collaborate during the design phase to ensure that structural systems accommodate both initially planned and future medical equipment and can avoid intrusive and costly structural modifications in the future.
Challenging equipment demands
Heavy live loads. Structural engineers classify the weight of medical equipment, as well as furniture and building occupancy weights, as live loads. Healthcare facilities are required to accommodate live loads between 40 pounds per square foot (psf) in patient rooms to 80 psf in corridors. The weight of commonly used pieces of equipment often exceeds code minimum design loads, such as MRIs with 3.0 Tesla magnets (each weighing 25,000 pounds). When distributed over the footprint of the magnet, this equates to a 300 psf uniformly distributed live load.
The path that equipment will travel during installation to its intended location must also be considered during design (figures 1 and 2).
Equipment's travel path within a facility must be taken into consideration
Without a feasible interior travel path, equipment can be brought in through an exterior wall
Shielding. Protective shielding in a healthcare facility keeps out unwanted interference and isolates potentially harmful radiation and magnetic fields (figure 3). The electromagnetic waves generated by electronic devices may negatively affect or cause malfunctions in other, similar, electronic devices. Such effects are called Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI).
