For any occupancy, the most common building type in the Philippines is reinforced concrete. However, higher strength demands of the updated National Structural Code of the Philippines (NSCP) 2001 Edition have introduced uncertainty regarding the seismic response of existing buildings. Likewise, inadequate ductility has given rise to the possibility of excessive failure, if not total collapse. Poor implementation and enforcement of the code for reasons that go beyond just technical, such as those that are related to socio-economic, cultural and even political issues, further exacerbate the predicament concerning the structural soundness of these buildings.
Motivated by the foregoing facts, this study focuses on the enhancement of the seismic response of reinforced concrete buildings. Energy-based analysis is best suited for this purpose because of its associated concepts that lead to more tangible and easily understood results, better insights, and reliable output of information upon which sound judgment and decisions related to design can be drawn. Highlighted herein is the use of hysteretic dampers, which has gained wide acceptance in the global structural engineering community owing to advantages that are to be elaborated hereinafter.
Analytical building models employing conventional steel braces with slip and slip-bilinear restoring force characteristics are used to obtain baseline information to which the results for the bilinear hysteretic dampers are compared. A parametric study is performed using the hysteresis rules, number of stories, earthquake input, and brace or damper strength as the main parameters. A practical application using a real three-storey school building is also presented. Evaluation of the seismic performance is based on Nonlinear Earthquake Response Analysis and Nonlinear Static (Pushover) Analysis. The basic criteria for evaluation are inter-story drifts and energy absorption capacity.