Adequacy of the seismic analysis methods for single-column-bent viaducts considering regularity and higher modes effects

摘要

Several definitions have been used concerning structural regularity. A structure is considered here as regular, if its responses obtained from different well recognized analysis methods do not show significant differences. In this paper, the effects of the inclusion of higher modes on the response of a class of reinforced concrete viaducts with different degrees of irregularity have been investigated. The seismic responses of continuous span single-column-bent viaducts have been studied through the comparison of the results obtained from different pushover-based analysis methods. Commonly used single and multi-mode pushover-based analysis methods have been utilized and their corresponding results have been compared with the results obtained from simpler methods such as the so-called uniform load procedure, as well as the more sophisticated inelastic time history analysis methods. For the class of the bridges under consideration, those configurations for which the effects of the higher modes are considerable have been identified and categorized as irregular, for which the minimum analysis requirements have been indicated in order to achieve a reliable bridge response. In contrast, the conditions in which a configuration may be classified as regular have been demonstrated and the adequacy of the simplified methods for the analysis of such models has been examined. The regularity issue has been discussed initially based on an expression developed by other researchers. Another index has also been introduced here for the attainment of a more realistic representation of the structural particulars of such bridges consist with the analysis methods specified in the AASHTO Specifications.