## 2 Description of Prototype Seismically Isolated Buildings
### Design of Seismically Isolated Buildings  
The framing plane of three, five, and ten-story isolated buildings previously studied by [PERSON] and [PERSON] [13] were selected as the prototype buildings. Figure 2 presents the configuration of buildings of which the plan is 21 m by 21 m with a story height of 3.5 m. The intermediate reinforced concrete (RC) moment-resisting frames adopted as lateral force resisting systems and isolation systems were designed according to the provisions of ASCE/SEI 7 [14]. For the maintenance and inspection of isolators and their connecting members, the isolating story-height of each prototype building was assumed to be 2500 mm. In order to compare the collapse probabilities of isolated buildings located at low-to-moderate seismicity regions to those of corresponding buildings at high seismicity regions, the prototype buildings were designed according to different levels of seismic hazards. As shown in Table 1a, different wind load conditions were considered in designing prototype buildings in order to reflect the contribution of the design wind load as well as the design seismic load on determining the force-displacement relation of an isolation system. For the seismic design of a series of prototype buildings, some of them were assumed to be built at high seismicity regions of which the MCE spectral accelerations at short and 1-s periods are \(S_{S}\) = 1.50 g and \(S_{1}\) = 0.60 g, respectively. The spectral accelerations, \(S_{S}\) = 0.46 g and \(S_{1}\) = 0.19 g, were selected as the representative of moderate seismicity and applied for the seismic design of the other prototype buildings. The isolated buildings were located on a soil condition with site class C (with shear wave velocity \(V_{S30}\) = 360 to 760 m/s). Using the seismic design parameters summarized in Table 1b, the preliminary design according to the equivalent lateral force method had been carried out to confirm the minimum design criteria and to calculate member forces. Then, a dynamic analysis procedure was utilized to validate the design results of the prototype isolated buildings. A more detailed design procedure of the prototype isolated buildings can be found in the research of [PERSON] and [PERSON] [13]. Figure 2: Building plan and elevation of prototype isolated buildings. Using isolators including lead rubber bearings (LRBs), natural rubber bearings (NRBs), and friction sliding bearings (FSBs) shown in Figure 3, their capacities and distributions on the isolating floor plane were determined to meet the design requirements for lateral restoring forces and property modification factors. This study utilizes experimental results described by [PERSON] and [PERSON] [13]. To specify realistic values for the stiffness and strength of isolators, the nonlinear force-displacement properties of LRBs and NRBs were obtained from cyclic test results shown as a black line in Figure 3. According to the method of prototype test described in ASCE/SEI 7 [14], hysteretic behaviors were evaluated. The cyclic tests were performed for three fully reversed cycles of loading at the maximum displacement. The vertical load was considered as the average dead load plus one-half the effects due to live load on isolating bearings. The NRBs remained elastic subjected to the maximum displacement and linear hysteretic behaviors were adopted for shear deformation, while the LRBs presented a yield of lead bar embedded in isolating bearings. In comparison to the acceptance criteria defined as \(\pm 15\%\) variations for the nominal design values, test results for isolators were validated, since test results for the stiffness and strength characteristics fell within the range of acceptance criteria. Table 2 summarizes the monotonic properties of isolators selected for the prototype buildings. Since the isolation systems should remain elastic under wind loading, their lower bound properties for \(Q_{y}\) values should be equal to at least the design wind load of each prototype building.