Padang Earthquake, Nick Alexander, Day 3
Degenkolb Team Day 3
by Nick Alexander
On day 3, we looked at buildings with different types of occupancy. We investigated Mariani International Hotel, Yos Sudarso Private Hospital, Nurul Iman Mosque, and a couple of government buildings: BAPPEDA (Regional Planning Department – Provincial Level) and Financial Department.
BAPPEDA (Regional Planning Department – Provincial Level)
The BAPPEDA building is one of 25 government buildings that were either heavily damaged or collapsed during the September 30, 2009 Padang earthquake. The building was previously a 3-story reinforced concrete frame building with brick infill and cladding. The heavy building consisted of reinforced concrete columns that are regularly spaced. From exterior observation, the building does not seem to have horizontal irregularity. The façade on all 4 sides of the building are tapered as shown in Fig 1. The building is a classic example of a soft-story case at the first story level (Fig 2). The 2 upper-stories are stiffer than the first story hence concentrating all the damage within the first story level.
After the first story lost its strength, the building must have shifted, twisted, and experienced a lot of deformation. Fig 3 shows out of plane failure of the brick claddings on the back side of the building. A lot of the buildings with brick infills in Padang do not have the walls doweled to the perimeter framing. If dowels are provided they are usually very minimal and dowels to the top frame are usually never provided.
The columns are reinforced with large smooth rebars with very small-sized ties used confinement. All of the ties seem to have 90 degree bend, which are much more susceptible to open up during earthquake excitation compared to the 135 degree bended ties (Fig 4). The concrete in the columns was completely crushed suggesting low concrete compressive strength used in the columns (Fig 5 & 6).
Fig 7 shows an emergency exit stairs that is obviously no longer in service after the collapse of the first story. EERI team leader, Greg Deierlein managed to obtain some information regarding the occupancy and evacuation situation during the earthquake. There were approximately 80 people in the building during the earthquake. Two people were crushed trying to escape the first floor. Everyone else survived by either running out of the first floor (about 30 people) or remaining on the upper floors until the earthquake had stopped. Since the earthquake occurred about 5:15 pm local time, a lot of people had already left from their office buildings. Unfortunately, this was not the case for this specific office building.
The building was obviously red-tagged, meaning it was unsafe to enter the building (Fig 8 ). Building assessment and tagging in Padang has been done on a voluntary basis provided by different universities through-out Indonesia. Each of the universities would send out a team to provide damage assessment on different type of buildings. For the specific case, the assessment effort from the different universities has been coordinated by the largest university in Padang, University of Andalas.
photos by Nick Alexander
