Shear failure of building floor beams due to December 7, 2016 Pidie Jaya earthquake

The 6.5 Mw magnitude earthquake experienced in Pidie Jaya Regency on December 7, 2016 caused the failure of several structures including the District Attorney’s Building with almost all the beams on the first floor observed to have shear cracks. Besides that, some flexural cracks were also found, although only in a few places. This study aimed to determine the cause of the shear failure in the building and the amount of deformation observed in the structures due to the earthquake. Therefore, an assessment was conducted in the field to determine the quality of concrete and the adequacy of shear reinforcement installed. A time history analysis was also performed using the Pidie Jaya earthquake history recorded by the Meteorology, Climatology and Geophysics Agency (BMKG). The results showed the required shear strength of the floor beams due to earthquake load was lower than its shear capacity due to a low compressive strength of the concrete in the beam and installation of insufficient shear reinforcement. Furthermore, the flexural strength required in the beams in some places was also greater than the available flexural capacity. The lateral deformations due to the earthquake were also observed to be very large thereby causing the inter-story drift of the building structures to exceed the value allowed by earthquake-resistant building standards (SNI 1726:2012). This subsequently led to the failure of the building floor beams, however, since the strength of the column was greater than the required standard, no crack was observed in the columns.