Structural responses considering the vertical component of earthquakes

Salazar, Alfredo Reyes; Haldar, Achintya

doi:10.1016/s0045-7949(99)00031-0

Cited by 25 publications

(5 citation statements)

References 6 publications

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“…Other consequences of this mass modeling error follow from this problem with modal frequencies. For example, it is known (Salazar and Haldar, 2000) that extreme axial loads in the columns of building frames are underestimated when vertical motions are present, especially when plastic hinges form in the frames. Shifting of the modal frequencies for the vertical vibration modes complicates this problem, since the first vertical vibration mode has been shown (Ju et al, 2000) to play a crucial role in determining the maximum absolute column axial force and maximum absolute beam moment in building frames.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Implications of vertical mass modeling errors on 2D dynamic structural analysis

Whalen

Archer

Bhatia³

2004

Structural Design Tall Build

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The use of diagonal (lumped) mass matrices is common in dynamic structural analysis. The assumptions made when performing the lumping procedure, however, are not always consistent with the underlying physical behavior and can therefore modify the dynamic properties of the modeled structure. The influence of errors in mass modeling for vertical degrees of freedom on dynamic behavior and seismic response is illustrated. We demonstrate that overestimation of the lumped masses associated with vertical displacements in 2D frame models of these structures leads to inaccurate modal periods and associated modal participation factors for dynamic response. The ramifications of these inaccuracies on seismic response are shown and implications in other dynamic analysis situations are discussed.

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Section: Conclusion and Discussionmentioning

confidence: 99%

Implications of vertical mass modeling errors on 2D dynamic structural analysis

Whalen

Archer

Bhatia³

2004

Structural Design Tall Build

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“…In Table 1 the peak horizontal ground component a g,H , the peak vertical ground component a g,V [14]. The average a g,V / a g,H ratio for the selected records equals 0.69.…”

Section: Calculation Of the Limit Aspect Ratio Based On Dynamic Analysismentioning

confidence: 96%

Limit height-to-width aspect ratios for slender base isolated objects of heritage architecture

Petrovčič¹,

Koren²,

Kilar³

2009

WIT Transactions on the Built Environment

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Seismic isolation has become a realistic alternative for decreasing the seismic vulnerability of heritage architecture. This article deals with a special technical aspect of base isolation design of slender rigid objects on elastomeric isolators, by considering the condition that the isolators cannot bear any tensile forces under simultaneous horizontal and vertical ground excitations. The main parameters that govern the response in this case are a) mass, mass position and height-to-width aspect ratios of the superstructure, b) stiffness, damping and plan arrangement of the isolators and c) expected horizontal as well as vertical earthquake acceleration components and their interconnections. The limit height-to-width aspect ratios were obtained for horizontal and vertical accelerations from the Eurocode 8 response spectra, as well as from dynamic analyses of seven near-fault ground motion records. The results are presented as maximum allowable aspect ratios for different vibration periods, ground conditions and design ground accelerations. The inclusion of vertical accelerations in governing equations is extremely important because different horizontal and vertical seismic loading combinations might significantly influence the maximum allowable height-to-width aspect ratios. The article concludes that the results from the response spectrum analysis are conservative. Although, in some ground motion records, the critical combination of horizontal and vertical response accelerations can also produce smaller limit height-towidth aspect ratios.

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“…Similar results and conclusions were drawn by other researchers. For instance, Salazar and Haldar [34] developed a time-domain nonlinear finite element computer program to evaluate the seismic responses of SMRFs by applying the horizontal and vertical components of 13 earthquake ground motion (one record from EI Centro earthquake of 1940 and 2 ground motions recorded during the 1994 Northridge earthquake) simultaneously; similarly, Macrae et al [35] carried out inelastic NLTHAs of nine 2D SMRFs using a suite of ground-motion records with different characteristics to estimate the effect of vertical component of ground shaking. More recently, a low-rise code-compliant SMRF was designed by Di Sarno [36] and was subjected to combined horizontal and vertical earthquake loading of seven records from the 2011 Christchurch (New Zealand) earthquakes, characterized by a large ratio between vertical and horizontal PGAs.…”

Section: The Effects Of Earthquake Ground-motion Vertical Componentsmentioning

confidence: 99%

Advancing fracture fragility assessment of pre‐Northridge welded column splices

Song

Galasso

Kanvinde

2019

Earthq Engng Struct Dyn

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A refined probabilistic assessment of seismic demands and fracture capacity of Welded Column Splice (WCS) connections in welded steel moment resisting frames (WSMRFs) is presented. Seismic demand assessment is performed through cloudbased nonlinear time history analysis (NLTHA) for two case-study structures, i.e. a 4-and a 20-story WSMRFs. Results from NLTHA are assessed through a probabilistic seismic demand analysis framework to derive fracture fragility of WCS connections. To this aim, the study investigates (1) optimal ground-motion intensity measures for conditioning probabilistic seismic demand models in terms of global (i.e., maximum inter-story drift ratio) and local (i.e., peak tensile stress in the flange of WCSs) engineering demand parameters of WSMRFs; (2) the effect of ground-motion vertical components on the longitudinal flange stress of WCS connections and their resulting fracture fragility; and (3) the effect of WCS capacity uncertainties on the fracture fragility estimates of those connections. For the latter case, an advanced Finite Element Fracture Mechanics-based approach proposed by the authors is employed to capture aleatory and epistemic uncertainties affecting fracture capacities. The focus is on pre-Northridge WCS connections featuring partial joint penetration and brittle materials, making them highly vulnerable to seismic fracture. Fracture fragility results for the case-study structures are compared and discussed, highlighting the importance of the considered issues on fragility estimates, particularly in the case of high-rise structures. Findings from the study contribute shedding some light on the influence of seismic demand and capacity uncertainties on the assessment of fracture fragility of WCS connections. These findings can guide similar performancebased assessment exercises for WSMRFs to inform, for instance, the planning and design of retrofitting strategies for those vulnerable connections.

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Structural responses considering the vertical component of earthquakes

Cited by 25 publications

References 6 publications

Implications of vertical mass modeling errors on 2D dynamic structural analysis

Implications of vertical mass modeling errors on 2D dynamic structural analysis

Limit height-to-width aspect ratios for slender base isolated objects of heritage architecture

Advancing fracture fragility assessment of pre‐Northridge welded column splices

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