Vulnerability Assessment of RC Frames Based on Alternative Intensity Measures Considering the Characteristic of Pulse-Like Ground Motions

Abstract eng:
Pulse-likke ground mootions are a special class of ground motio ons that are paarticularly chaallenging to ch haracterize forr earthquake hhazard assessm ment. These motions m are chharacterized by y a “pulse” in n the velocity ttime history of o the motion,, and they are typically veryy intense and have h been obsserved to causse severe dam mage to structuures in past eaarthquakes. Soo udies show thhat the severee response off it is particularly importannt to characterize these groound motionss. Previous stu y measuring tthe intensity of o the ground motion m using spectral accelleration of thee structure is nnot entirely accounted for by elastic first-mode period of a structu ure (Sa(T1)). This paper will use sev veral alternatiive intensity measures too p ground motions iin vulnerability assessmentt. The ability oof these inten nsity measuress characterize the effect of pulse-like g motion ns will be evaaluated. to characterizze pulse-like ground Pulse-likke ground mootions and ordinary groundd motions aree selected as input to carryy out incremeental dynamicc analysis. Struuctural responnse and vulneerability are eestimated by using u Sa(T1) as a the intensitty measure. The T impact off pulse periodd on structuraal response is studied throough residual analysis. By comparing th the differencee between thee structural ressponse and vuulnerability cu urves using puulse-like groun nd motions an nd ordinary grround motionss as the input,, the impact oof velocity puulse on vulneerability is innvestigated an nd the shortccoming of usiing Sa(T1) to o characterizee pulse-like gground motioon is analyzed. Then, vvector-valued ground mottion intensityy measures(S Sa(T1)&RT1,T2, Sa(T1)&RPGVV,Sa) and inelaastic displacem ment spectra(S Sdi(T1)) are used to charactterize the dam mage potentiall of pulse-likee ground motioons, the efficciency and sufficiency of th these intensity y measures arre evaluated. The study sh hows that: thee damage potential of near fault f ground motions m with vvelocity pulse is closely relaated to the pul ulse period of strong s motionn n and nonlineear features off the structure. The above fa factors should be taken intoo as well as firrst mode periood of vibration account whenn choosing a reasonable r gro ound motion pparameter to characterize c th he damage pottential of pulsse-like groundd motions. Vullnerability currves based on n Sa(T1) show w obvious diffeerences betweeen using nearr fault ground d motions andd ordinary grouund motions, as well as pu ulse-like grouund motions with w different pulse periodss as the input. When usingg vector-valuedd intensity meeasures such as a Sa(T1)&RTT1,T2, Sa(T1)&R RPGV,Sa and in nelastic displaacement spectra, the resultss of vulnerabillity analysis arre roughly thee same. Thesee ground motio on intensity measures m are m more efficient and sufficientt to characterizze the damagee potential of near n fault grouund motions with w velocity pulse.  p

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