Parameter-Normalized Probabilistic Seismic Demand Model Considering the Structural Design Strength for Structural Response Assessment

Abstract

Probabilistic seismic demand models (PSDMs) are crucial components of performance-based seismic design frameworks used for predicting structural responses. In accordance with the elastic limit states of structures, this study normalized two key parameters within a PSDM namely the intensity measure (IM) and engineering demand parameter (EDP). Normalized EDP (EDPN) is the ratio of the structural response to the elastic limit state response of the structure. Similarly, the IM is normalized (IMN) based on the IM ratio at the corresponding moment. The inclusion of the structural elastic limit state information allows the IMN to consider the structural design strength. A parameter-normalized PSDM was constructed based on the IMN and EDPN. Finite element models of two typical isolated bridges were established using the OpenSees software by utilizing 1736 carefully selected ground motions as load inputs. To evaluate the structural response prediction capability of the parameter-normalized PSDM, 14 typical IMs were considered, and efficiency and sufficiency criteria were employed. The findings demonstrate that the parameter-normalized PSDM outperforms the traditional PSDM in predicting the structural responses. Additionally, during the normalization process of the IMs, the form of the IM was standardized into ground motion scaling factors, which smoothened the differences among various IMs in the PSDM. Finally, ground-motion prediction equations for normalized IMs were developed, and hazard curves were calculated through seismic hazard analysis.

Keywords: Probabilistic seismic demand model, normalized, intensity measures, hazard curve, isolated bridges