Manabu Yoshimura

Gravity Load Collapse of Reinforced Concrete Columns with Brittle Failure Modes

Abstract During the 1995 Kobe earthquake, dozens of concrete buildings suffered complete collapse at an interme-diate story. Such collapse is believed to have occurred due to the gravity load collapse following shear failure of Steel Reinforced Concrete (SRC) or Reinforced Concrete (RC) columns at a certain intermediate story. To study this collapse tests of RC column specimens were conducted. Test parameters were axial load and loading history. The tests have revealed that: 1) collapse occurs when shear force decreases to about zero, 2) axial load level is decisive for the collapse behavior, 3) loading history occasionally has a significant effect on the collapse behavior including a failure mode, and 4) a change in vertical deformation increment vs. lateral drift increment relations until collapse can be explained by the flow rule in plastic theory considering reduced failure surface.

Collapse Time of Reinforced Concrete Buildings with Brittle Columns

Buildings with brittle columns are in danger of gravity load collapse and may be hazardous in the event of future earthquakes. To plan for building evacuation, the time required for such buildings to collapse must be known. This study thus uses dynamic analysis to examine the collapse time of reinforced-concrete (RC) buildings designed according to old Japanese codes. Model lateral load vs interstory drift relations are represented based on previous collapse tests of brittle columns. The results reveal that (1) in most cases, the time between shear failure and collapse is very short for individuals to safely evacuate a building, and (2) the collapse time can be long for earthquakes with long durations.