Delta-2 effect

Frame members have additional criteria. Sidesway limits are applied to frame systems to reduce the chance of progressive collapse and to minimize P delta effects on columns. It is quite possible to maintain acceptable response of individual members but experience large lateral displacements of roofs and upper floors which cause collapse. The sidesway limits indicated in the tables are fairly liberal and should not be exceeded without detailed analysis or testing. 

However, several assumptions are inherent in this interpretation of the data. First, it is assumed that the change in the observed effect (such as conversion of 850°F+, percentage denitrogenation, etc.) is linear with respect to time. Thus a linear delta-effect per period of time could be established and intermediate data could be adjusted to a MfreshM activity corresponding to that observed at the reference period and at any desired temperature. Second, it is assumed that the intermediate process parameter variations had no adverse effect on the catalyst deactivation function. For example, operation at constant temperature for a given interval of time would produce the same catalyst deactivation as varying temperatures (within limits) over the same interval of time. 

Additional detailing should be addressed for the use of these R factors per ASCE/SEI 7 which include the effects of the sohds or fluids stored and their interaction with the structure, p-delta effects, and other requirements within other design standards. 

The current stiffness matrix is modified by considering the last yielded hinge identified at Stage (2) and it is returned to Stage (1) for the next pushover step. Note that second-order (P-Delta) effects can be readily considered in IRSA by adding the so-called geometric stiffness matrix to the first order stiffness matrix at each pushover step. 

Determination of the drift, overturning moment, and P-Delta effect... 

Determination of the drift, overturning moment, and P-Delta effect that are the direct results of the action of the lateral seismic forces... 

For one, realism means incorporating all pertinent sources of material and geometric nonlinearity that are expected to arise. This should include, for example, plastic-hinge formation zones for moment-resisting frames, brace buckling for braced frames, and P-Delta effects. Nonsimulated failure modes, such as the shear failure of members or the brittle failure of beam-column joints, can be incorporated in the analysis a posteriori. Still, they essentially remove the model s ability to track structural behavior beyond their first occurrence. This means that whenever nonsimulated failures are found to have occurred, one cannot trust the model to provide estimates beyond that point. 

CoUapse criterion Collapse variability Component deterioration Nonlinear dynamic analysis P-delta effect Structural modeling strategies... 

The structural model of Fig. 6a includes a leaning column with zero flexural stiffiiess to account for the P-delta effect resulting from gravity loads that are not directly applied to the frame (Haselton et al. 2009). This leaning column is loaded with a vertical load at each story level representing half of the total system gravity load that is not directly tributary to the columns of the frame (NIST GCR 10-917-8 2010), as shown in Fig. 6b. 

Global Seismic Sidesway Collapse and the P-Delta Effect... 

Fig. 11 P-delta effect on the backbone curve of an inelastic SDOF system (Modified from Ibarra and Krawinkler 2005)...

In multistory frames, gravity loads may substantially impair the complete structure or only a subset of stories (Gupta and Krawinkler 2000). The local P-delta effect may induce collapse... 

Adam C, Ibarra LF, Kiawinkler H (2004) Evaluation of P-delta effects in non-deteriorating MDOF structures... 

Gupta A, Krawinkler H (2000) Dynamic P-delta effects for flexible inelastic steel stractures. J Struct Eng 126 145-154... 

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