Framework for Seismic Vulnerability Assessment of RC High-rise Wall Buildings

With population growth and urbanization, the number of high-rise buildings is rapidly growing worldwide resulting in increased exposure to multiple-scenario earthquakes and associated risks. The wide range in the frequency content of expected ground motions impacts the seismic response and vulnerability of this class of structures. While the seismic vulnerability of some high-rise building classes has been evaluated, the vulnerability of these structures under multiple earthquake scenarios is not fully understood, highlighting the pressing need for the development of a framework to address this complex issue.
This study aims to establish a refined framework to assess the seismic vulnerability of RC high-rise wall buildings in multiple-scenario earthquake-prone regions. A deeper understanding of the responsive nature of these structures under different seismic scenarios is developed as a tool to build the framework. The framework is concluded with analytically-driven sets of Seismic Scenario-Structure-Based (SSSB) fragility relations.
Different nonlinear modelling approaches, software, and key parameters contributing to the nonlinear analytical models of RC high-rise wall structures are investigated and verified against full-scale shake table tests through a multi-level nonlinear modelling verification scheme. The study reveals the superior performance of 4-noded fibre-based wall/shell element modelling approach in accounting for the 3D effects and deformation compatibility. A fundamental mode damping value in the range of 0.5% is found sufficient to capture the inelastic response when initial stiffness-based damping matrix is employed.
A 30-storey reference wall building located in the multiple-scenario earthquake-prone city of Dubai (UAE) is fully designed and numerically modelled as a case study to illustrate the proposed framework. A total of 40 real earthquake records, representing severe distant and moderate near-field seismic scenarios, are used in the Multi-Record Incremental Dynamic Analyses (MRIDAs) along with a new scalar intensity measure.
A methodology is proposed to obtain reliable SSSB definitions of limit state criteria for RC high-rise wall buildings. The local response of the reference building is mapped using Net Inter-Storey Drift (NISD) as a global damage measure. The study reveals that for this class of structures, higher modes shift the shear wall response from flexure-controlled under severe distant earthquakes to shear-controlled under moderate near-field events. A numerical parametric study employing seven RC high-rise wall buildings with varying height is conducted to investigate the effect of total height on the local damage-drift relation. The study reveals that, for buildings with varying heights and similar structural system, NISD is better linked to the building response and well correlated to structural member damage, which indicates that only one set of SSSB limit state criteria is necessary for a range of buildings.
The study concludes with finalising the layout of the proposed refined framework to assess the seismic vulnerability of RC high-rise wall buildings under multiple earthquake scenarios. A methodology to develop refined fragility relations is presented where the derived fragility curves are analysed, compared, and correlated to varying states of damage.
Finally, a methodology to develop Cheaper (simplified) Fragility Curves (CFC) using the defined limit state criteria with a lower number of records is proposed along with a new record selection criterion and fragility curve acceptance procedure. It is concluded that fairly reliable CFCs can be achieved with 5 to 6 earthquake records only.