Abstract
Near-fault events can cause severe damage to civil structures, including bridges. Many studies have demonstrated that the seismic assessment is not straightforward. Usually, dealing with near-fault ground motion, the structural analysis is performed using Nonlinear Response-History Analysis (NRHA) but in the last years, many authors have tested existing pushover-based procedures originally developed and validated using far-field events. Between those procedures, the Incremental Modal Pushover Analysis (IMPAβ) is a pushover-based procedure specifically developed for bridges that, in this work, was applied to a case study considering near-fault pulse-like ground motion records. The records were analyzed and selected from the European Strong Motion Database. In the paper the results obtained with IMPAβ together with other standard pushover procedures, are compared with NRHA and incremental dynamic analyses; the vertical component of the motion has been also considered. Results obtained with the bridge case study demonstrate that the vertical seismic action has a minor influence on the structural response and that IMPAβ is confirmed as a very effective pushover-based method that can be applied also for near-fault events.
Highlights
Near-field ground motions (NF) differ from ordinary ground motions
Results obtained with the bridge case study demonstrate that the vertical seismic action has a minor influence on the structural response and that IMPAβ is confirmed as a very effective pushover-based method that can be applied for near-fault events
In the case of NF ground motions, the vertical action becomes relevant; its consideration or neglect thereof should be discussed. This issue has been considered and the necessity of performing vertical and horizontal pushover has been evaluated by testing the IMPAβ procedure substituting modal pushover analysis (MPA) with the Extended Modal Pushover Analysis (EMPA) [19], which considers all the components of the records
Summary
Near-field ground motions (NF) differ from ordinary (far-field) ground motions. The proximity to the fault renders the effect of the global displacements and the mutual displacements of the opposite sides of the fault very evident in the records: (i) the vertical motion component maximum values often exceeds the horizontal component [1]; long period velocity pulses can be generated by (ii) earthquake directivity and (iii) fling-step [2], (iv) differential input displacements at the base of the piers [3]. Due to the significant amount of time required for analysis and complexity required to perform several NRHAs and to the specific complexity of the dynamic method, it is useful to investigate alternative static methods that can provide results with lower computational effort For these reasons, some authors proposed the use of pushover analyses to investigate the response of bridge structures under near-fault seismic input [14,15]. In the case of NF ground motions, the vertical action becomes relevant; its consideration or neglect thereof should be discussed In this work, this issue has been considered and the necessity of performing vertical and horizontal pushover has been evaluated by testing the IMPAβ procedure substituting MPA with the Extended Modal Pushover Analysis (EMPA) [19], which considers all the components of the records.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
