We are hopeful that by presenting this work we can assist other departments in seismically active areas at being proactive in considering and possibly planning for seismic requirements in their next linac purchase, with the hope that delays and inefficiencies might be avoided, and safety might be improved.Ī linac installation (VUB, linac, and couch) will place more than 12,000 kg (26,500 lb) compressive force onto the vault floor. Both of the cases presented here refer to anchoring of the Varian (Varian Medical Systems, Palo Alto, CA, USA) Universal Base‐frame (VUB) however, the basic principles of seismic fixation can be applied to any linac frame. This work details the steps taken by our institution to address the seismic requirements for an existing vault (anchoring for an existing base‐frame) and also for implementing seismic anchoring in a new vault. We believe that it may be unappreciated that many radiation therapy facilities are located in seismically active areas within the US and are therefore required to adhere to updated building codes. Since both projects were considered new implementations, the updated state requirements were required to be adhered to for both projects.
#Hilti anchors in exs concrete slab code
It was noted at this point that the current implementation of seismic fixations (i.e., the existing base frame) no longer met the updated state building code requirements.
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The ASCE’s latest seismic recommendations, which were signed into law by the Utah state legislature, were consulted during the planning phase. In 2018, our institution began planning for two projects: (a) the replacement of a linac in an existing vault, using the existing grouted‐in base frame and (b) the construction of a new linac vault at a satellite facility. Starting with the 2010 ASCE Standard 7–10 titled “Minimum Design Loads for Buildings and Other Structures”, there are specific requirements for non‐structural components, such as medical and lab equipment to be anchored to the building structure, i.e., typically fixation to the floor, with the anchorage strength based on the earthquake forces of the locality. The newest seismic recommendations are used and implemented into local building codes based on the USGS earthquake maps.
![hilti anchors in exs concrete slab hilti anchors in exs concrete slab](https://www.hilti.com/medias/sys_master/images/h24/h6e/9513835429918.jpg)
In the United States, the American Society of Civil Engineers (ASCE) updates structural requirements for building standards. Of course, ground motion varies depending on specific location relative to the fault line, and expected forces are specified on maps published by the United States Geological Survey (USGS). Therefore, along the Utah/Idaho Wasatch fault line, the potential for earthquake ground motions are similar to those expected in California. Such earth movement can cause surface displacements of up to 7.6 m (25 feet). Surface faults are shown in red.īased on analysis of fault scarps (rock uprisings due to earthquakes) geologists have calculated a 50‐year earthquake probability of greater than 6.75 on the Richter scale in the Wasatch Front region of 43%, and a greater than 7.5 on the Richter scale probability of 15%. Shows the active surface fault map of the Wasatch Front in Utah. An understanding of the seismic landscape can facilitate an appropriate installation at minimal additional cost. It is the facilities task to verify the correct installation of a linac in their specific location. In both cases the vendor provided seismic calculations serve as baseline from which a facility should be work from. In addition the actual workflow is straight forward and vendor recommendations can be used. For a prospective seismic installation the new linac base frame can be directly installed with the necessary strength.
![hilti anchors in exs concrete slab hilti anchors in exs concrete slab](http://cfnewsads.thomasnet.com/images/large/540/540964.jpg)
Understanding the additional load requirements for the locality allows to account for the existing fixation and can potentially reduce the work needed to achieve seismic fixation requirements. Knowledge of the previously applied fixation of such is needed and exploratory removal of grouted floor helped in the verification.
#Hilti anchors in exs concrete slab verification
The installation of a new linac into an existing vault requires verification of a structurally sound base frame. For the linac installation to be seismically stable, the linac base frame has to be seismically fixed into the vault floor. Here, we describe the necessary steps taken to ensure a seismically sound installation of our linacs. Since we are in a seismic active area, changes in the local code required us to start placing the new linacs seismically stable. In our institution we have recently acquired new linear accelerators, one of which had to be installed in an existing vault and one in a new vault. The local building requirements to secure medical equipment in seismically active areas in the United States are based on recommendations of the American Society of Civil Engineers.