Parametric study on the influence of infills on the displacement capacity of rc frames for earthquake loss estimation

Student: Bin Zhang
Supervisors: Dr Rui Pinho


The displacement capacity of a reinforced concrete frame is not only essential for the structure to resisting lateral ground motions during an earthquake, but is also important for the evaluation of earthquake losses from a potential earthquake. This property of a frame is determined by many factors, such as material properties, structural configuration, construction quality, and workmanship, etc.Generally, it is possible to link the displacement capacity of a frame to some principle structural characteristics, such as height of the structure.

DBELA, a displacement-based earthquake loss assessment model, utilizes the height of the structure and generates a series of expressions for evaluating the displacement capacity of reinforced concrete frames. The expressions have been verified in this work with the assistance of a finite elements package.

With respect to the displacement capacity of an infilled frame, more factors need to be considered. The properties of infills and frames are both of significant importance, as well as the interaction between them. Several failure modes may occur due to the different combinations of the dominant properties.

Consequently, modelling of infills is a complex task, which requires great effort to be devoted. None of the current models is capable of representing masonry infills precisely and completely. However, an equivalent strut model may be sufficient to model the effect of infills for seismic design with satisfactory accuracy and simplicity. This model has been developed by many researchers in the last decades, and has exhibited evident advantages in simulating infills in numerical calculations.

By utilizing an equivalent strut model that is integrated in the aforementioned finite elements package, parametric analysis has been undertaken to study the displacement capacity of infilled frames. The results demonstrate that the displacement capacity is reduced generally because of the stiffening and strengthening of the structure due to infills, and the extent of decrease in displacement capacity varies with the structural characteristics of the infills. Finally, a series of coefficient and regression relationships are proposed to represent displacement capacities of different structure types.

You may download a digital version of this MSc dissertation here.