SEISMIC ASSESSMENT AND RETROFITTING OF THE WEST SUMATRA BPBD OFFICE BUILDING USING SHEAR WALLS

Abstract

The structural reliability of public buildings in seismic-prone areas is essential to ensure safety and functionality. Accordingly, the BPBD office building in Padang, West Sumatra, Indonesia, was evaluated due to observed deficiencies, including cracking, material degradation, and inadequate lateral resistance under Indonesian building standards. Structural modeling and analysis using ETABS showed that the existing structure does not meet inter-story drift requirements, with excessive drift at the second floor. In addition, several columns experienced moment and axial failure, and several beams experienced shear failure, reducing seismic performance. To address these deficiencies, a global retrofitting strategy was implemented by adding RC shear walls along the weak axis. Re-analysis of the retrofitted model demonstrated significant improvements: inter-story drift values complied with code requirements, column internal forces decreased by up to 95% moment, 93% shear, and 30% axial, while beam internal forces were reduced by 81% in moment and 63% in shear. Furthermore, floor slab analysis revealed inadequate flexural capacity under seismic loads. Strengthening with Fiber Reinforced Polymer (FRP) sheets successfully increased the slab moment capacity from 0.89 t.m to 2.62 t.m, exceeding the external moment requirement of 2.51 t.m. These results confirm that a combined retrofitting strategy using shear walls to enhance global stiffness and FRP to reinforce slab flexural strength provides an effective solution to improve seismic resilience and ensure the building’s safety as a disaster management facility. Fragility curve analysis further indicates that, after retrofitting, the probability of exceeding all damage states decreases significantly, confirming a substantial reduction in seismic damage risk.