150 B. Pridham et al. Reviews of the dynamics of proposed designs during planning can be helpful for identifying areas of the structure that will have limited participation in the vibration modes associated with laneways. Similarly, finite element modelling can be helpful for development of de-tuning strategies, such as modifications to framing to alter and effectively de-couple the dynamic response at laneways and sensitive occupancies. Ultimately there may be physical limitations on what can be done with the base parking structure to arrive at the design criteria for the facility. Adding sufficient mass to the system to suppress the impulsive response associated with axle hop may not be possible. Other factors, such as cost, schedule, constructability and space limitations may rule out change to structure such that other strategies must be considered. Path control strategies are usually applicable to new build scenarios since they can involve changes to layouts and structure, which can be addressed early in design. In a retrofit or re-use scenario, a vibration survey is required to carefully assess the proposed site(s) of planned spaces, the nature and frequency of disturbances and control measures appropriate to planned occupancy. In a retrofit, controls might include renovations to existing architectural, mechanical and plumbing systems, which can be costly. 19.3.3 Receiver Control The third component addresses vibration controls at the receiver space. This might include isolation of equipment within the space and/or isolation of the space itself. There are numerous passive and active vibration control systems commercially available for a wide range of research and medical tools—see [6–9]. Design or selection of the correct isolation system usually includes measurements to determine the temporal and spectral characteristics of the parking vibrations (among other sources), at planned equipment locations. Some customization of the isolation system is typically required to accommodate unique toolsets, space constraints etc. Whole-room isolation may be required for ultra-sensitive spaces located near, or sharing structure with the parkade. The general concept is to build an isolated box around the room that effectively decouples the space from the noisy surroundings. This approach requires structural and acoustic treatments that prevent or suppress incoming vibrations with isolation elements (springs, flex connections etc.), secondary support structures isolated from the base building and, where necessary, sound isolation elements (masonry and/or double-stud walls, drywall ceilings etc.), for control of noise. Receiver control strategies are applied to new builds and renovation/re-use scenarios. In some cases, receiver isolation may be sufficient to satisfy vibration criteria; however, the authors caution the use of this strategy as the first line of defense. A holistic solution that includes a combination of source, path and receiver controls should always be considered. 19.4 Case Study: Ambulatory Surgical Clinic Located on the Ground Floor of a Multi-Story Mixed Occupancy Building The approaches to vibration control discussed in Sect. 19.3 were applied during the design of a surgical clinic located on the ground floor of a multi-story concrete parking garage. Some of the key observations and results from this work are presented in this section as a case study on how parking garage vibrations can be addressed in vibration-sensitive facilities. 19.4.1 Facility Description The case study involves a ten-story medical office building (plus mechanical penthouse), constructed as part of a new medical campus located in a major urban center. The first floor of the building is dedicated to ambulatory care and ambulatory surgery use, levels two through six are a concrete parking structure and levels seven through ten are pan joist concrete structure to be occupied by a mix of administrative and clinical uses. Some photos of the partially completed building and architectural plans for levels one and two are shown in Fig. 19.2. Note the location of an expansion joint spanning top-to-bottom of the plans at the mid-point of the parking structure. The use and occupancy of the first floor have undergone several iterations that included varying degrees of vibration sensitivity. During the detailed design phase of the project the area was designated as shelled space, with the possibility of future use for general surgery and radiosurgery (cancer treatment). Screening level studies of vibration performance were
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