Comparison of ASCE/SEI Standard (2010) and Modal Pushover Based Ground Motion Scaling Procedures for Pre-Tensioned Concrete Bridges

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Civil Engineering, Turkey

Approval Date: 2015


Supervisor: YALIN ARICI


The seismic design and evaluation of large bridges is a demanding task owing to the significant size and the structural characteristics of these systems. Although elastic analysis methods are regarded as sufficient for common, uncritical bridges; complex analysis methods such as non-linear time history analysis (NTHA) are often required for non-standard and/or important bridges. The selection of the ground motions that will be used in non-linear time history analysis is a crucial task in this regard as the results of time history analyses will show a wide variability according to the utilized earthquake record. Furthermore, in order to predict the expected demand in accordance with the seismic hazard conditions of the site, the selected ground motions are usually modified by the scaling procedures. A separate but equally important goal is to obtain the engineering demand efficiently with a small number of representative motions. Within this context, in this study, the relative performance of two ground motion scaling methods, namely the Modal Pushover Based Scaling (MPS) and ASCE/SEI Standard (2010) procedures, are investigated using a number of ground motion sets selected from a suite of 35 ground motions for the NTHA of a representative large bridge, the Demirtas Viaduct. The system, composed of 28 spans and various expansion joints, is idealized with two different analytical models. Three different target earthquake levels are used for both models in order to determine the effect of the scaling of the ground motions at different hazard levels. The final goal of the study is to establish the sensitivity of the demand parameters and the efficiency of the ground motion scaling techniques considering different target demand levels and structural models.