Jembatan Siti Nurbaya (large concrete bridge south of the city)

The construction on Jembatan Siti Nurbaya began in 1994, was stopped due to a bad economy, and eventually completed in 1999. Jembatan Siti Nurbaya is the most substantial bridge over the Batang Arau, located at the South of the city center spanning roughly 70m. The bridge is approximately 10m wide and is a standard concrete box girder. The bridge itself faired very well in the September 30th earthquake with no apparent damage. The approaches, which consist of soil confined by concrete retaining walls, held up during the earthquake but sustained damage. The sidewalk on the South West approach separated and settled from the concrete retaining wall approximately 12”, as a result of an earthquake in 2007. This same location settled an additional 18” in the recent earthquake. In addition to the measurable separation, the south approach suffered damage in that the entire approach dropped relative to the bridge and the pavement split in two clear cracks forming deep longitudinal voids. Additionally, the North approach currently has about a two-inch crack spanning the entire width of the bridge just a few feet from the bridge-approach connection.

This bridge could serve as a key component for tsunami evacuation for two reasons: the bridge sits approximately 26 feet above the road below therefore the bridge is approximately 30 ft above sea level, which could potentially act as an evacuation site; the second use of the bridge is to facilitate numerous pedestrians, motorbikes and even cars, over the bridge to grant access to higher ground.

Photos to follow.

BAPPEDA – City Planning Provincial

This BAPPEDA building (provincial planning) was constructed in 1980.  The structural system is reinforced concrete with masonry infill.  The architectural features of the building created a larger mass on the top floors.    The first floor appears to have a smaller floor plan with a rim of exterior columns around the building supporting the floors above.  It was a soft first story building and that it went from a 4 story to 3 story building; specifically, the North East corner of the building completely collapsed on the first floor.  The exterior columns on the first floor were approximately 20”x20” in dimension, with large, smooth bars and rather small stirrups.  The bar spacing was anywhere from 2.5 to 3.75 inches and alarmingly large aggregate was found.  Smooth river rocks were used for the aggregate and some of the pieces found were up to 5”.  Approximately, 80 persons were inside the building during the earthquake – 50 ran out immediately, 30 stayed on the upper floors and two were killed near the entrance on the first floor.  The two victims were both crushed as the first floor came crashing down.  At the back of the building, several infill falls fell out and various contents from within the building fell onto the pavement below.  Planning documents were found among the debris, including tsunami preparation and planning booklets.

Sentral Pasar Raya

Built approximately three years ago, Sentral Pasar Raya is located in the dense city center of Padang.  Sentral Pasar Raya contained many small shops within the four-story building.  The top floor consisted of a modest food court in the center and an open roof.  The building is a reinforced concrete moment frame with masonry infill.  The earthquake occurred at 17:16 on a Wednesday, and it is unclear as to how many people were inside when the ground shaking began.  Various people recounted a number of deaths ranging from 3 to 36; currently the precise number is unknown.  The earthquake caused a partial collapse, with a large extent of the damage occurring at the back of the building.  A few cooling towers were located on the roof at the back of the building.  It is likely that the uneven weight distribution accounts for the abundance of column failure that can be found at the back of the building.  The first story completely collapsed at the back, and the second story partially collapsed.  In addition, several columns/beams/floors/stairs appear to or may have failed throughout the entire building, although the extensive damage is centralized at the back.  The column located at the back of the building (the North East corner) failed extensively and clearly displayed stirrups tied to a meager 90° (rather than the US standard of 135°).  Additionally, every stirrup in the column was oriented along the same corner of the cage, rather than staggered about all corners.  The columns and beams throughout the building contained deformed bars, approximately size #6.