# Smart Deployable Scissor Lift Brace to Mitigate Earthquake Risks of Soft-Story Buildings
### Soft-Story Mechanism  
Recent earthquakes have shown that many existing buildings are vulnerable to damage or even collapse during a strong earthquake. Damage and collapse due to the \"soft-story effect\" are most often observed during and after an earthquake. A soft story refers to a building's level that exhibits significantly reduced resistance, stiffness, or insufficient ductility (energy absorption capacity) to withstand the stresses induced by an earthquake. Soft-story buildings are characterized by a particular floor that features extensive open space (see Figure 1). Such floors, often, are used as parking garages, large retail areas, or floors with substantial openings. The design of these buildings introduces a sudden shift in the lateral strength and stiffness along their height, potentially triggering what is known as the \"soft-story mechanism\". This occurs when a large lateral force is applied, creating high rotational stress on the outer sections of the ground-level columns. At the same time, the upper structure acts almost like a rigid body, with this imbalance in behavior having the potential to cause, eventually, the entire building to collapse. Strong earthquakes have caused thousands of injuries, fatalities, and significant economic losses, with building failures often linked to soft/weak story configurations. These structures, particularly vulnerable during seismic events, have been responsible for major damages in past earthquakes, such as the 1995 earthquake in Hyogoken-Nanbu [2], the 1971 earthquake in San Fernando [3], and the 1985 and 2017 Mexico City earthquakes [4; 5; 6; 7]. Figure 1: Cross-section of a typical soft-story building. The Northridge earthquake of 17 January 1994 resulted in a significant level of damage to buildings that had open basements used for parking [8]. In 1997, in Jablpur, India, the earthquake revealed the handicap of Indian buildings with a soft first story [9]. During the earthquake which occurred on 12 May 2008 in northwestern Sichuan, China, many buildings were significantly damaged, with drifts up to 7.5% (soft-story effect) [10]. The partial collapse of the building \"Casa dello Studente\" during the earthquake which occurred in L'Aquila, Italy, on 6 April 2009 involved the failure of all columns on the ground floor, attributed to a soft/weak story mechanism [11]. The peculiar behaviour of masonry infill RC frames, in which most of the lateral deformation is concentrated in the open ground story and the upper stories remain vertical and mostly undamaged, was observed in several past earthquakes in India, such as the 2001 Bhuj earthquake [12], the 2004 Great Sumatra earthquake [13; 14; 15], the 2005 Kashmir earthquake [16], and the 2011 Sikkim earthquake [17; 18]. The Lorca, Spain, earthquake of 2011 was a significant event that caused extensive damage to buildings in the area. The seismic activity primarily affected buildings with three to five stories and wide openings on the ground floor, which exhibited a structural vulnerability known as a \"soft-story\" pattern [19; 20]. The 2011 Tohoku Earthquake, which is also referred to as the 'Great East Japan Earthquake', was the most powerful earthquake ever recorded in Japan and resulted in the collapse and damage of 45,700 and 144,300 buildings, respectively. Most reinforced concrete buildings that collapsed and were damaged during the earthquake had large openings on the ground story, resulting in weak/soft-story effects [21]. The buildings that experienced the damage during the 2015 Nepal earthquake were found to have either large openings on the ground story or no infill walls, resulting in the plastic hinges experiencing large inter-story drifts [22]. The presence of soft story irregularities was identified as one of the primary factors contributing to the damage of the building in the 2015 Ranau earthquake [23].