Experimental Study on Two-Hour Fire Resistance Performance of Slabs in Modular Buildings under Loads

For a floor of a building with no less than four stories and no more than twelve stories, the two-hour fire resistance performance should be satisfied. In the case of slabs with steel studs, no two-hour fire resistance performance has been proposed in Korea. In this study, the two-hour fire resistance performance of slabs with steel studs performing as structural elements of modular buildings was evaluated. These specimens were redesigned based on the typical slab used in Europe and North America by modifying the 45 mm fire-resistant board to achieve two-hour fire resistance. The experimental results showed that the FR-001 specimens with 140 mm mineral wool applied to the lower slab and the FR-002 specimens containing 100 mm lower-slab glass wool and 150 mm upper-slab mineral wool did not satisfy the two-hour fire resistance performance, owing to the rapid deformation of the specimens after 75 and 110 min, respectively. However, the FR-003 specimens containing 100 mm glass wool, 150 mm mineral wool in the upper slab, and concrete in the slab satisfied the two-hour fire resistance performance requirement.

Relationship between advancing abutment pressure and deformation of surrounding rock in a roadway: A case study in Helin coal mine in China

The deformation stages of the working face of a mine in front of the roadway were defined based on the location of the roadway and the coal wall in different deformation zones. Observational data of the advancing abutment pressure and the surrounding rock deformation of the roadway from Helin coal mine were analyzed using least squares fitting. The results show that the distance between the boundary of the rapid deformation stage and the deceleration deformation stage and the position where the advancing abutment pressure is equal to the original rock stress is 0.8 m. The distance between the boundary of the large deformation stage and the stable small deformation stage and the peak value of the advancing abutment pressure is 0.3 m. A theoretical analysis indicated that the boundary between the rapid deformation stage and the deceleration deformation stage is located at the intersection of the advancing abutment pressure curve and the original rock stress curve. The boundary between the large deformation stage and the stable small deformation stage is located at the peak value of the advancing abutment pressure.

Recrystallization of ice enhances the creep and vulnerability to fracture of ice shelves

<p>The initiation and propagation of fractures in floating regions of Antarctica has the potential to destabilize large regions of the ice sheet, leading to significant sea-level rise. While observations have shown rapid, localized deformation and damage in the margins of fast-flowing glaciers, there remain gaps in our understanding of how rapid deformation affects the creep and toughness of ice. Here we derive a model for dynamic recrystallization in ice and other rocks that includes a novel representation of migration recrystallization, which is absent from existing models but is likely to be dominant in warm areas undergoing rapid deformation within the ice sheet. We show that, in regions of elevated strain rate, grain sizes in ice may be larger than expected (~15 mm) due to migration recrystallization, a significant deviation from solid earth studies which find fine-grained rock in shear zones. This may imply that ice in shear margins deforms primarily by dislocation creep, suggesting a flow-law exponent of n=4 in these regions. Further, we find from existing models that this increase in grain size results in a decrease in tensile strength of ice by ~75% in the margins of glaciers. Thus, we expect that this increase in grain size makes the margins of fast-flowing glaciers less viscous and more vulnerable to fracture than we may suppose from standard model parameters.</p>

Nacre-based carbon nanomeshes for a soft ionic actuator with large and rapid deformation

Hierarchically porous carbon nanomeshes from nacre for fast ion penetration of soft ionic actuator with large and rapid deformation.

A New Way of Visualizing Iceland’s Crustal Deformation

A novel method of calculating strain rates from GPS data shows the South Iceland Seismic Zone is experiencing rapid deformation, including inflation near the island’s most active volcano.