Torsional effects induced by an eccentric wall in one-storey structures

This thesis investigates the torsional effects caused by a single eccentrically positioned reinforced concrete wall in one-storey structural systems. The study is motivated by observations from the 2012 Emilia-Romagna earthquakes, during which many industrial buildings suffered severe torsional damage or collapsed because their reinforced concrete walls were located away from the building's center. When the center of stiffness is offset from the center of mass, lateral loading generates a torsional moment that increases displacement on the flexible side of the structure. The analytical torsional amplification factor proposed by Silvestri et al. (WCEE 2024), expressed as Eq. (4), is evaluated by comparing its predictions with SAP2000 finite element results for six parametric structural models with plan aspect ratios ranging from 0.50 to 2.25. Initial validation shows that the original equation underestimates the numerical amplification factor by an average of 27.3%. Incorporating shear deformation into the wall stiffness calculation reduces the average error to 20.8%. Replacing the continuous polar stiffness term with the discrete expression, (1/n) Σ(kc•xi² + kc•yi²), produces mixed results. The analysis shows that Eq. (4) represents the torsional resistance of the column system using a single scalar polar stiffness term, without accounting for the separate contributions of the x- and y-directions. In square column grids, symmetry makes these directional contributions identical, so the simplified representation remains valid and the discrete formulation improves the prediction. In rectangular, however, the two directions contribute differently, meaning that a single scalar term whether continuous or discrete cannot fully capture the structural behaviour. These findings suggest that future improvements to Eq. (4) should focus on developing a direction-dependent polar stiffness formulation rather than simply replacing the continuous geometric term with a discrete one.