Investigation of progressive collapse resistance of cantilevered structure based on concrete strength

<span style="color: rgb(50, 64, 78); font-family: Arial; font-style: italic; background-color: rgb(241, 243, 245);">Turkey is a region known for its high seismic activity, and unfortunately, many of its existing buildings are not well-prepared to withstand earthquakes. This study delves into the consequences of removing ground floor columns, either due to architectural modifications or damage from earthquakes to the structural integrity of buildings. To investigate this, a model simulating a cantilevered structure was developed, allowing for a detailed analysis of potential collapse mechanisms. The structural model, designed using STA4CAD software, represents a seven-story building with a ground floor height of 4.2 meters and a typical floor height of 3.2 meters. The building has a cantilever length of 1.5 meters, with 5-meter spacing between axes in both the X and Y directions. A uniform slab thickness of 150 mm and the load-bearing system is composed of columns and beams. These designs were then transferred into the Extreme Loading Structures (ELS) software, where further analysis was conducted. In the ELS program, models were created with varying concrete classes of C10, C15, and C20, incorporating specific cross-section dimensions and reinforcements. The primary focus of the analysis was to assess the buildings' vulnerability to progressive collapse, particularly when critical ground-floor columns were removed. The evaluation followed the guidelines set out in the "Design of Buildings to Resist Progressive Collapse" (UFC 4-023-03) code. The findings of this study are significant. Buildings constructed with C10-grade concrete were found to be highly susceptible to collapse when either interior or corner columns were removed. On the other hand, buildings with stronger C15 and C20 concrete demonstrated greater resilience, only suffering damage rather than complete collapse upon the removal of corner columns. These results underscore the importance of both material strength and architectural design in ensuring the seismic safety of buildings in earthquake-prone areas.</span>