Effect of infill walls and plaster for a four storey R/C building

Abstract

Infill walls are non-structural elements, which are mainly used for architectural purposes. Besides contribution of infill walls is ignored during the structural analysis, the effect of the infill walls are usually taken into account through the application of additional loads and masses appropriately distributed along the interfaces between the surrounding frame and the infill walls. In doing so, the stiffness and strength contribution of the latter elements as well as their interaction with the members of the Reinforced Concrete (RC) frame are also ignored. Practically some of the earthquake design codes like Turkish code neglect the effects of the non-structural infill walls. However the presence of infill walls significantly increases the stiffness and the strength of a frame. The reasons of this increment are high in-plane stiffness of infill and the composite action of the infill and the frame. On the other hand, plastering significantly affects the behaviour of infill walls. Thus, the dynamic characteristics of a building also affected by the infill walls of building having plaster or not. The objective of this study is selected to compare the behaviour of infill walls with and without plaster by focusing on dynamic characteristics of a 4-storey residential R/C building in Eskisehir, Turkey. Natural periods, mode shapes and damping ratios of the building were determined for two different construction stages by using ambient vibration test. To obtain experimental dynamic characteristics, Enhanced Frequency Domain Decomposition (EFDD) technique was used. These 4-storey residential R/C building is located in Eskisehir, Turkey. The investigated building in which seismic loads are jointly resisted by frames and structural walls. There are only one shear wall along x-direction and four shear walls along y-direction. The floor area of the building is 400 m2 and story heights are 2.83 m. Total area of infill walls for one storey are 5.44 m2 and 10.75 m2 at x-direction y-direction, respectively. As a result of this study, vibration measurements are established that, plaster significantly changed the dynamic characteristics of building. Decrease in the periods both x and y directions and also torsional period showed that the plaster increases the lateral stiffness of the infill walls and thereby it increased the lateral stiffness of the building.