جستجوی مقالات مرتبط با کلیدواژه "intensifying dynamic excitation" در نشریات گروه "برق"

In this paper, the application of Endurance Time method in seismic analysis of bridges is explained. The Endurance Time method is a novel seismic analysis method based on time history analysis in which a structure is subjected to a predefined intensifying acceleration function. First, six concrete bridges were modeled. Three Endurance Time acceleration functions were applied to the models and the average of the responses were calculated. Next, the time history analysis was conducted using seven real accelerograms scaled using the method recommended by FHWA 2006 to be compatible with the design spectrum of seismic AASHTO guideline for a site with soil type C in Berkeley, California. The average of the responses of these seven analyses is considered as reference. Scaling the mentioned accelerograms over a wide range of hazard levels, Incremental dynamic analysis is performed. Finally, the comparison of the response of ET and time history analysis and also comparison of ETA with IDA curves reveals good agreement. The major advantage of ET method over time history and IDA methods is less computational effort needed for the analysis. This saving in time is resulted due to the possibility of predicting response by fewer analyses despite maintaining the necessary accuracy.

Endurance Time (ET) method is a dynamic analysis procedure using intensifying excitation. The ET excitation functions are generated so that structural performance can be assessed at different excitation levels in a single response history analysis. The ET accelerograms which have been generated so far possess response spectra consistency; this means that the duration consistency has not been directly considered. Strong-motion duration can influence the response of structures which have stiffness or strength degrading characteristics. In this paper, several well-known strong-motion duration definitions are studied in the ET method context. Ground motions are scaled to spectral acceleration of code spectrum as well as the ET records; furthermore, the ET records are scaled to have consistent duration compared to real ground motions considering different strong-motion duration definitions. In order to determine which definitions have the highest correlation with structure responses, several SDOF structures which have cyclic deterioratingbehavior in stiffness and strength are subjected to both the ET records and real ground motions. Sincemaximum inter story drift and maximum displacement of a structure subjected to several motions with roughly same acceleration spectra but different motion durations,are approximately identical and in this paper, aim is to pursue the influence ofmotion durationin responses, those indices which are based on energy and accumulative damageare employed. Correlation of each definition with structure responses has been examined by comparing the results of the ET records and real ground motions. Good performance of the ET records in nonlinear region can be deduced due to the high correlation between the results of ET records and real ground motions. This paper provides an approach for considering the duration consistency in ET accelerograms. The efficiency of this approach for current ET accelerograms is aslo investigated.