Performance evaluation of low-rise infilled reinforced concrete frames designed by considering local effects on column shear demand

The interactions between reinforced concrete(RC)frames and infill walls play an important role in the seismic response of frames,particularly for low-rise frames.Infill walls can increase the overall lateral strength and stiffness of the frame owing to their high strength and stiffness.However,local wall-frame interactions can also lead to increased shear demand in the columns owing to the compressive diagonal strut force from the infill wall,which can result in failure or in serious situations,collapse.In this study,the effectiveness of a design strategy to consider the complex infill wall interaction was investigated.The approach was used to design example RC frames with infill walls in locations with different seismicity levels in Thailand.The performance of these frames was assessed using nonlinear static,and dynamic analyses.The performance of the frames and the failure modes were compared with those of frames designed without considering the infill wall or the local interactions.It was found that even though the overall responses of the buildings designed with and without consideration of the local interaction of the infill walls were similar in terms the overall lateral strength,the failure modes were different.The proposed method can eliminate the column shear failure from the building.Finally,the merits and limitations of this approach are discussed and summarized.

Size effects in two-dimensional layered materials modeled by couple stress elasticity

In the present study,the effect of material microstructure on the mechanical response of a two-dimensional elastic layer perfectly bonded to a substrate is examined under surface loadings.In the current model,the substrate is treated as an elastic half plane as opposed to a rigid base,and this enables its applications in practical cases when the modulus of the layer(e.g.,the coating material)and substrate(e.g.,the coated surface)are comparable.The material microstructure is modeled using the generalized continuum theory of couple stress elasticity.The boundary value problems are formulated in terms of the displacement field and solved in an analytical manner via the Fourier transform and stiffness matrix method.The results demonstrate the capability of the present continuum theory to efficiently model the size-dependency of the response of the material when the external and internal length scales are comparable.Furthermore,the results indicated that the material mismatch and substrate stiffness play a crucial role in the predicted elastic field.Specifically,the study also addresses significant discrepancy of the response for the case of a layer resting on a rigid substrate.