Seismic design and analysis, vulnerability assessment of RC frame building, Juba, South Sudan

Reinforced concrete (RC) is a widely used building material known for its strength and durability. By combining the compressive strength of concrete with the tensile properties of steel, RC structures can withstand significant loads, making them ideal for buildings and critical infrastructure. This adaptability has made RC a preferred choice in urban construction, especially in developing regions such as Juba in South Sudan. However, RC buildings in Juba are particularly vulnerable due to the lack of formal seismic design standards, inadequate reinforcement details, and limited awareness of earthquake-resistant practices. Consequently, many regional structures need to be better designed to withstand seismic forces, increasing the risk of failure during earthquakes. This study evaluates the seismic behavior of a typical G + 2 RC frame building in Juba, designed initially to withstand gravity loads when subjected to seismic forces. Incremental Dynamic Analysis (IDA) and Time History Analysis (THA) with SAP2000 v23.2.0 software analyze critical components such as beam-column connections. The seismic loads were calculated using the equivalent static method according to the IS:1893–2016 standard. The results show that although the building meets the criteria to prevent collapse, significant weaknesses in the beam-to-column connections affect its seismic performance. These results underscore the need for increased reinforcement and the urgent development of seismic design guidelines and retrofit strategies specific to construction practices in Juba. This study provides important insights for engineers and policymakers to improve the seismic resilience of RC buildings, protect infrastructure, and enhance public safety in the rapidly urbanizing regions of South Sudan.