Numerical Evaluation of Columns’ Uplift in Bracing Structures
Subject Areas : Analysis of Structure and EarthquakeAbozar saleh 1 , seyadmehdi zahrayi 2
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Keywords: Keywords: Uplift force, bracing, Reaction support, EBF, CBF,
Abstract :
ABSTRACT One of the forces occurring during an earthquake is the tensile force that arise in the columns. This phenomenon is called ‘uplift’. It causes damage in column, base plate and anchor bolts. In the absence of appropriate control it may cause the building to collaps. Knowing the reasons which lead to such phonomenon will clarify the point that such phonmenon needs to be controlled. The present study has tried to offer solutions by which the uplift in columns can bereduced. This study has tried to by offering solutions the uplift in columns is reduced. To do so, the numerical models for two buildings were applied in which the location of the braced were changed and the number of brace columns were increased hoping to reduce the uplift strength. For each building, a separate model was built. In the models the proposed ways to reduce uplift were applied. Both EBF and CBF types of the braces were assessed. The numerical results obtained from the study indicate that using the single brace at the corners of the building, aiming to neutralize the uplift does not seem to be appropriate and that even the existence of an additional intermediate frame braced for further support might be needed. The present study showed that the increase in the number of span bracing in different places (situations) are effective in reducing the uplift more than 50%. Also, CBF in lateral columns and EBF for intermediate columns are better ways to reduce uplift, and that different numerical results according to the location of the column in plane.
