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چکیده
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To eliminate the inherent energy dissipation deficiency of self-centering walls, hybrid self-centering walls (HSWs) have been developed by employing internal or external energy dissipating (ED) mechanisms. Mild steel bars have been extensively used as energy dissipators among ED mechanisms due to their affordability and simplicity. This study investigated the effect of ED bars layout on the damage, response features, collapse probability and collapse risk of HSWs. To this end, five different layout scenarios were defined first, and their response was studied by developing numerical models. Conducting nonlinear static and dynamic analyses (IDA), the scenarios damage, response features, collapse probability and risk were estimated and further examined to determine the optimal ED bars layout. Fragility analysis was performed on global and local scales, using IDA results, to estimate scenarios collapse probability. The results revealed that the wall with ED bars at the boundary elements outperformed other scenarios. Placing ED bars at the boundary elements of HSWs decreases the self-centering capability, fundamental period, collapse probability and the extent and severity of damage (especially in toe regions), while increases the energy dissipation capacity, adjusted collapse margin ratio and structural demand. Increasing ED bars cross-sectional area increases the extent and severity of damage. Using IDA results, the wall with ED bars at the boundary elements achieved the lowest ductility ratio; moreover, the response modification factor 3 was recommended for the strength-based design of HSWs. An optimality index (OI) was proposed herein to interpret the results quantitatively and determine the optimal layout. The calculated OI showed that placing ED bars at the boundary elements or along the wall width can be considered the optimal ED bars layout for achieving better seismic performance and decreasing the collapse probability and seismic risk of HSWs.
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