Verification of some Eurocode 8 rules for simplified analysis of structures

Student: Juan Pablo Angel
Supervisor: Dr R Pinho

Abstract

EUROCODE 8 presents several rules for simplified analysis of structures. This work focuses on three of those rules: the expression used to estimate the fundamental period of framed structures, the base shear reduction factor λ, and the implication that equivalent linear analysis can only be used for buildings that are regular in height. Several models are analyzed in order to verify the appropriateness of these rules. The first rule uses the expression T1=C1H3/4 to estimate the fundamental period of frame structures. This equation was developed for Californian buildings that might have different materials, configuration and construction parameters than new European structures and thus may not be applicable in all cases. The second rule states that a base shear reduction factor λ equal to 0.85 can be used when a building is at least 3-storey high and has a fundamental period vibration lower than 2Tc. In the last rule, the use of equivalent linear analysis is forbidden for irregular buildings in height. The verification intends to show that equivalent linear analysis may be used even for irregular buildings; in the majority of the cases it leads to over prediction of the response and it is proposed that this overprediction be used to scale up the base shear from modal response spectrum analysis.

Keywords: equivalent linear analysis; seismic loads;