Which type of building tends to be brittle and may have numerous interior walls preventing floor collapse?

The type of building that tends to be brittle and may have numerous interior walls preventing floor collapse is unreinforced masonry (URM) buildings. These structures are typically made from bricks and mortar without any reinforcing elements such as steel bars or mesh, which contributes to their brittleness.

In URM buildings, the walls are often load-bearing, and the lack of tensile strength means that under stress, these walls can crack or fail rather than flex. This property makes them vulnerable during seismic activities or other forces that create movement, leading to a situation where the floors may not drop straight down but could be supported briefly by the remaining walls unless those walls also fail.

The presence of numerous interior walls can create additional support, temporarily preventing a complete floor collapse, but it also raises concerns regarding the overall integrity of the structure during a collapse scenario. URM buildings may exhibit a tendency to break apart rather than collapse in a way that can leave voids for search and rescue operations, which is crucial for structural collapse rescue scenarios.

Other building types listed, such as reinforced concrete buildings, steel frame buildings, and lightweight steel structures, have their own structural properties and are designed to handle loads differently. For instance, reinforced concrete has added tensile strength, while steel frame