Seismic assessment of a RC case study building using the simple lateral mechanism analysis, SLaMA, method

The seismic assessment of an existing structure is a complex procedure. In the evaluation of the structural capacity, difficulties arise in the definition of the lateral resisting members, in the estimation of the lateral capacity from component to system level. The identification of the local and global mechanisms, depending on the hierarchy of strength at subassembly level, is a challenging task. Nowadays, advanced numerical analysis procedures, implemented in user-friendly commercial software, are commonly adopted in the current practice to overcome the difficulties in the use of non-linear analyses. Nevertheless, their accuracy strongly depends on the ability of the numerical model to capture all the probable failure mechanisms. To help the user in the assessment of the probable failure mechanism and to have a first estimation of the building lateral capacity, the Simple Lateral Mechanism Analysis (SLaMA) method has been recently developed and included in the NZSEE 2016 guidelines. SLaMA is a simple and reliable "by-hand" tool to derive the local and global mechanism of a structural system and the corresponding capacity curve. This paper deals with the application of the SLaMA to an existing RC building severely damaged during the Christchurch earthquake (2011, New Zealand). The lateral capacity of four 2D resisting systems was assessed following the SLaMA method. The results of a refined nonlinear numerical model were used to assess the accuracy and reliability of SLaMA. The good match confirmed that SLaMA can be a useful and simple tool to have a first estimation of the building lateral response. It allows to identify the main structural weaknesses driving the user to the development of more refined nonlinear models.