## 2 UAV Video Image Collection Program
### Case Study: NHERI Converging Design (Phase II) Shake Table Test Program  
To prototype seismic design solutions for mass timber buildings, a series of shake table tests were performed on a full-scale six-story mass-timber building with a seismic lateral-force resisting system using post-tensioned (PT) mass timber rocking walls (Figure 1). The 6-story building was deconstructed and reconstructed from a previous 10-story mass timber building (referred to as the NHERI Tallwood Building [27]). The 6-story mass timber building had a height of 20.73 m and a floor plan of 10.52 m \(\times\) 10.46 m. The building used a self-centering seismic lateral-force resisting system composed of cross-laminated timber (CLT) rocking walls in the east-west direction and mass plywood panel (MPP) rocking walls in the north-south direction. To dissipate seismic input energy, the CD Phase II test series incorporated buckling-restrained boundary elements (BRBs) installed at the bottom of the east and west MPP rocking walls. In all phases (10- and 6-story configurations), an operable prefabricated stair tower was designed into the building [28]. Instrumentation of the test building specimen included 602 channels of analog sensors to record various dynamic responses during shake table testing. All analog measurements were synchronized at a sampling rate of 256 Hz. In the present study, the motion of the roof was recorded using 22 uniaxial micro-electro-mechanical system (MEMS) accelerometers, which served as the ground truth measurements to evaluate the accuracy of the proposed UAV vision-based method. Detailed processing steps for the ground truth measurements and a comparison plan are discussed in Section 5.1. A total of 18 tests were conducted during the CD phase II test series, corresponding to 18 input ground motions identified with motion identification 1 through 18, i.e. MID 1-18. Among these tests, nine were captured by UAV imagery. Four earthquake events are used to generate the earthquake motion inputs used for these nine tests, namely the 1994 Northridge Earthquake, the 2004 Niigata Earthquake, the 2010 Fer  
Figure 1: The 6-story mass timber building specimen for the shake table test program of NHERI Converging Design Project (Phase II) at the LHPOST6. and the 2010 Maule Earthquake. These earthquake motion inputs are scaled to different intensity levels, where each intensity level corresponds to a specific percentage of the Risk-Targeted Maximum Considered Earthquake (MCE\({}_{\text{R}}\)) that was referenced for the design of the building specimen based on the approach described in Section 21.2.1 in ASCE 7-22 [29]. The MCE\({}_{\text{R}}\) refers to the earthquake that leads to a 1% probability of structural collapse within a 50-year period [29]. Table 1 shows detailed information of the earthquake motion inputs used in the present UAV-based analysis, including input directions, intensity levels, and achieved peak input accelerations (PIAs), which is a subset of the earthquake motion inputs used in the CD Phase II shake table test program. The measured peak responses of the building specimen under the nine monitored tests are summarized in Table 2. It is noted that structural responses (accelerations and displacements) discussed in this article are the absolute (total) structural responses, which include the shake table movement. For brevity, the term 'absolute' is omitted in subsequent presentation. In addition, the peak responses presented in Table 2 are the peak absolute valued responses in X or Y direction (regardless of +/ - in the given direction) calculated based on the measurements from the MEMS accelerometers near the estimated location of the center of mass of the floor plan at roof level. Roof displacement is the total roof movement determined by twice integrating the filtered acceleration time series (details on the displacement calculation are presented in Section 5.1.1).