No. 52 Parupuak Tabing school

October 18, 2009 by  
Filed under Structural Observations

The No. 52 Parupuak Tabing school is an elementary school in North Padang that has 170 students. There are three buildings on this small campus arranged in a C-shape, all single story rectangular buildings, two classroom buildings and a small office building. The structure of each building is the same: confined masonry walls with gabled wood framed roofs. All three buildings are separated from each other by several feet.

The larger of the two classroom buildings that is at the spine of the “C” was constructed in 1984 and suffered substantial damage in the earthquake. The building was in the process of being renovated and all of the interior transverse cross walls had been removed with the intent that they would soon be replaced. As a result the ring beams on the longitudinal sides of the building that originally spanned approximately 13 feet now spanned 6 times that length, and thus the beams sustained permanent deflection along with the brick walls below. However, the brick remained in the wall. This is consistent with the out-of-plane behavior seen in other parts of West Sumatra after the 2007 earthquakes. The connection of the roof trusses to the ring beams remained intact such that the roof rode along with the ring beams. Also, the brick gable walls at the north and south ends of the building also failed, another behavior commonly seen in the West Sumatra earthquakes and other recent earthquakes in Indonesia.

The smaller of the two classroom buildings on the south side of the “C” was originally constructed in 1986 with a classroom added in 2005. This building also sustained damage, though it was of a different nature than the larger building. The confined masonry walls remained intact but there were numerous places where the foundation footings and floor slabs settled, as much as 4 inches at the west end. The only solid walls are on the west end and it appears that the lateral forces concentrated in these walls, as the largest settlement was at the ends of these walls. There were also vertical shear cracks between the walls and the confining concrete columns.

The office building on the north side of the “C” had damage similar to the classroom building at the south end. There was evidence of settlement in the foundation and vertical shear cracks between the concrete columns and the brick walls.

The school was constructed adjacent to a drainage ditch and there is a swampy area next to the smaller classroom building. This suggests that liquefaction played a role in the settlement. There was also sand on the floor in the classroom building, which school officials reported has having bubbled up through the cracks. These same officials told us that they could see waves in the ground during the earthquake.

The school is currently closed and the students are being taught at an adjacent mosque. The small classroom building is currently being used as a temporary sleeping place for local soldiers.

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