Interaction of adjacent multi-storey RC frames at significant damage and near collapse limit states

Abstract

The interaction problem between adjacent multi-storey reinforced concrete structures with unequal storey levels and different total heights at different limit states for three intensity levels of seismic hazard is evaluated. The seismic performance of the external column of the tall building that suffers the impact from the upper floor slab of the adjacent shorter structure is under consideration. The critical column’s local requirements are checked at three different seismic demands according to the Eurocode 8 – part 3: (a) demand for damage limitation limit state (b) demand for significant damage limit state and (c) demand for near collapse limit state. More than 252 nonlinear dynamic step by step analyses have been performed. The results indicate that the column that suffers the impact appears to be in a critical condition due to high ductility demands when the limit state for the assessment is increased from damage limitation to significant damage and to near collapse state. As expected, the column that suffers the hit is always in a critical condition due to shear action. The limit state that is adopted for the evaluation of the pounding effect on the maximum shear requirements of the column slightly altered the results. However, the level of the seismic intensity influences the number of times the shear demands of the column exceed the available strength during the analysis. An increase of the developing requirements for inter-storey drift is also observed in all the cases where the seismic intensity is increased and the limit state becomes more exigent. The minimum gap distance between the adjacent structures that is required in order to eliminate the shear demands of the column seems to be depended on the limit state and the level of the seismic hazard that is used for the evaluation.