Study on Seismic Improvements of Existing Reinforced Concrete Buildings
Inadequate attention during design and construction of some of reinforced concrete (RC) buildings has raised
questions about the performance level of these existing buildings under future earthquakes. This paper aims to evaluate seismic
improvements of existing RC buildings. For this, total of five existing RC buildings constructed in major seismicity zone,
Mandalay city, are selected. Two possible improvement solutions are proposed; steel bracings and RC shear walls. Linear
static analysis is carried out for structural stability checking of existing structures based on UBC 97 code. From these
checkings, deficiencies of P-Δ effect are found in three existing pinned based buildings and deficiencies of torsional
irregularity are also found in two existing buildings. Firstly, structural improvements under linear static analysis are performed
to correct these deficiencies. Then, nonlinear static (pushover) analysis is carried out for performance evaluation of existing
structures. Seismic performance enhancement of the proposed existing buildings is evaluated to achieve basis safety objective
performance level described in FEMA 356. Results show that RC shear wall is more appropriate not as economic solution for
more deficient buildings (Model 5) whereas steel bracing is effective solution for less deficient buildings (Model 1, 2, 3 and 4).
Index Terms- Existing RC Buildings, RC Shear Walls, Steel Bracings, Seismic Improvements.