# Smart Deployable Scissor Lift Brace to Mitigate Earthquake Risks of Soft-Story Buildings
## 2 Smart Deployable Scissor Lift Brace  
### Conceptual Framework  
In the event of an earthquake, the high-frequency compressional P-waves (body waves) which travel fastest are the ones which get detected first by a seismic station. However, the most destructive surface waves (S-waves) travel more slowly and take longer to arrive. It is evident that electromagnetic (300,000 km/s) waves travel at much higher speeds than seismic waves (4-6 km/s) [40]. An EEW system, which consists of the combination of seismometers, sensors, communicators, computers, and alarm systems, uses the same concept to detect and warn of the arrival of seismic waves. It can be used to mitigate the risk of damages and losses in moderately and highly seismically active regions. In the traditional methods to determine the epicentral distance and location, the paramount seismic parameters include the arrival time difference between P-waves and S-waves. Hence, a long time would be required to predict the nature and arrival of an earthquake through these methods [41]. Conversely, EEW systems typically require only a few seconds of P-wave data (0.5-4 s) from two to six stations near the epicenter to detect an earthquake and characterize its location, origin time, and magnitude [42]. This helps provide an initial alert within a few seconds. Although the potential impact of a high-magnitude earthquake can affect a vast area, most of the resulting damage typically occurs within smaller epicentral distances near the fault line that is rupturing. As a result, the primary goal of any EEW system is to swiftly issue an initial alert within a matter of seconds. This urgency ensures that alerts are delivered to areas in close proximity to the epicenter [42]. Subsequent to this initial alert, there is a window of several seconds available for more precise information to be provided or for the alert to be extended to a broader region, particularly in the case of larger seismic events. In this current investigation, an EEW system is utilized to implement a scissor lift brace mechanism, enhancing the stiffness of the soft-story building during seismic events. Initially, the soft-story building is equipped with an undeployed scissor lift brace, con nected to a motor. These components are further linked to the EEW system and internet connectivity. In its undeployed state (Figure 3a), the scissor lift brace mechanism poses no hindrance to the open first story and operates seamlessly under normal conditions without seismic activity. Upon detection of an earthquake, the EEW system activates the mechanism by transmitting an earthquake alert, prompting the deployment of the scissor lift mechanism (Figure 3b). Prior to the actual seismic event, the mechanism activates a locking mechanism that secures it to the roof of the first story. This proactive measure imparts additional stiffness and strength to the open first story, preventing the formation of plastic hinges and reducing significantly the rotational demand on the structure. The system operates in an automatic mode, with the scissor lift brace retracting after a certain time has elapsed and restoring the open first story once the earthquake has subsided. This mechanism also serves as a valuable tool for evacuating individuals during an earthquake, with the scissor lift brace ensuring the structural safety of the building until all occupants have been successfully evacuated. The mechanism relies on electricity as its power source for deployment. Consequently, this system is most effective in buildings with a stable electricity supply and should be deployed, ideally, before the onset of an earthquake to ensure uninterrupted functionality while electric power is still available. A robust locking mechanism is integrated into this system to ensure secure and proper locking. This feature is crucial to deliver the necessary stiffness and strength precisely when faced with an actual earthquake. A flowchart in Figure 4 shows the sequence of operation steps of the proposed system.