Nonlinear Analysis of Pre-Northridge Steel High-Rise Building Using Modal-Pushover-Based Ground Motion Scaling Procedure

Nonlinear response history analysis provides a robust analytical approach to estimate and evaluate existing building performance but it is sensitive to the characteristics of input ground motion. ASCE 7-05 provides guidelines for selecting and scaling from individual ground motion records. Recently, researchers developed an alternative method called "modal-pushover-based ground motion scaling procedure" (MPS) that considers the strength and higher mode effects of the individual building in its selection and scaling methodology. A 24-story steel moment frame building with "pre-Northridge" connections is chosen as a case study to compare the response predictions of the ASCE 7-05 method and the MPS method. Based on comparison the inter-story drift ratios, the MPS method resulted in significantly lower demands than the ASCE 7-05 method. The case study includes a re-evaluation of the structure after a conceptual rehabilitation. Implications of the rehabilitation on the scaling of ground motion records when utilizing the MPS method are discussed.