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Ratios 'ρ' of the seismic bending moments under SVEGM over synchronous excitation in the

Ratios 'ρ' of the seismic bending moments under SVEGM over synchronous excitation in the

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This paper presents a novel, bridge-dependent approach for quantifying the increase of design quantities due to spatially variable earthquake ground motion (SVEGM). Contrary to the existing methods for multiple support bridge excitation analysis that are either too complicated to be applied by most practitioners or oversimplied (e. g. Eurocode 8, A...

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... In case of MSE, { } represents the displacements of the unconstrained degree of freedoms (DOF), when the ith support experiences the unit displacement and while all other supports are fixed. For SE case, r is the influence vector representing the rigid body displacements of the masses related to the active direction of the support motion [15]. ...
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p>Spatially variable earthquake ground motions yield the different structural demands compared to the conventional synchronous ground motions. In this paper, a cable-stayed bridge under on-site recorded spatially variable earthquake ground motions is analyzed and phenomena of response amplification based on in-situ monitoring are investigated. A calibrated numerical model of target bridge is prepared and both multi support excitation and synchronous excitation analyses are performed. The modal amplitudes of different structural components corresponding to different vibration modes are compared. The comparative analysis clarified the variation of overall response and localized amplification of engineering demands. MSE method at design phase should be considered to disclose the critical scenarios which are hard to identify by conventional design approaches.</p
... Extensive research has been carried out to investigate the MSE effects on bridges which has disclosed the response enlargement effects and increase in engineering demand parameters (EDPs). In the previous research, it is pointed out that the response amplification is linked to those modes (specifically the anti-symmetric ones) that usually are not excited by SE [1] . However, synthetic or spatially interpolated input motions were utilized and, bridges with simpler structural geometry and relatively shorter span lengths were considered [1] [2] . ...
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Extended structures such as long-span bridges are subjected to Multiple Support Excitation (MSE) in contrast to the simplified design Synchronous Excitation (SE). Under MSE, bridge supports experience spatially variable ground excitations due to wave time lag, coherency loss and local site-amplification effects, resulting in dissimilar structural response. Modern seismic design codes are rather deficient to tackle this issue and additional research is indispensable. Extensive research has been carried out to investigate the MSE effects on bridges which has disclosed the response enlargement effects and increase in engineering demand parameters (EDPs). In the previous research, it is pointed out that the response amplification is linked to those modes (specifically the anti-symmetric ones) that usually are not excited by SE. However, synthetic or spatially interpolated input motions were often utilized and, bridges with simpler structural geometry and relatively shorter span lengths were mainly considered. Investigation of MSE effects on long-span bridges with real seismic records is also desirable for the development of a robust design framework to reliably estimate the EDPs.
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