| As earthquake resistant design is not a requirement in Hong Kong construction, structural systems with high torsional eccentricity are not uncommon in Hong Kong buildings. This PhD study conducted a dynamic analysis on a one-story bi-walls asymmetric system to investigate the effect of the torsional resistance of wall, with or without considering the flexure-torsion interaction, on the response of the asymmetric system.;An experimental investigation was conducted on the behavior of eight half-scaled reinforced concrete (RC) cantilevered walls subjected to monotonic pure torsion. The test results including the failure mechanism, experimental torque-twist curve, torsional strength and torsional stiffness were discussed. In addition, various existing torsional models and the ACI Code were evaluated by comparing the predicted results with the experimental ones. The torsional skeleton curve of the wall is determined based on the softened membrane model for torsion (SMMT) and further adjusted by the conclusions drawn from the pure torsional tests.;A combined loading test was conducted on three cantilevered RC walls. A series of simplified interaction curves was developed based on the test results. The effects of the torque to bending moment (T/M) ratio on the failure mechanisms, crack patterns, strength and stiffness were discussed. It was also found that the ACI provisions gave very conservative predictions especially for walls under pure torsion or dominant torsion.;Finally, the dynamic analysis was conducted to investigate the seismic response of asymmetric structural systems by taking into account the torsional resistance of wall element and its interaction with flexure. A numerical, step-by-step integration procedure (average acceleration method) was used to solve the equation of motion. The element forces (torsion and flexure) obtained at the previous time step were used to determine the flexural and torsional hysteretic relations of the current time step through interaction curves. The analytical results showed that the exclusion of the torsional resistance of the wall does not always lead to a conservative estimation of the system response. The displacement of the stiff wall tended to be underestimated under most of the selected levels of ground motion if the interaction effect was neglected. The effect of wall torsion on the system response was more significant for the models with greater plan-asymmetry. |
