SEISMIC RESPONSE OF RC BUILDINGS WITH SHORT MASONRY INFILL WALLS USING PUSHOVER ANALYSIS

Columns are the most important elements of the buildings that having effective roles in sustaining and transferring the gravity and lateral loads to foundation. The shear failure of socalled «short columns» is a continual cause of collapse during earthquakes. Regular columns can be turned into captive columns by the addition of parapet infill in frame structures.unrestrained part of the column is a short column or captive column and its greater stiffness (compared with other, longer unrestrained columns in the system) must be considered in structural design. Short columns are very vulnerable to shear failure in earthquakes. Structural frames are often filling with masonry infill serving as partitions. Although the masonry infill usually is not considered in the structural analysis and design, their influence on the seismic behavior of the infilled frame structures is considerable. In the present study we use the strut model to capture the global effects of the masonry infill. One-storey and one-bay concrete frame is considered for designing in accordance with New Zealand, ACI and Turkish codes. Pushover analysis is adopted for the evaluation of the seismic response of the frames. The results of the cases are briefly presented and compared, and then the effect of partial masonry infill on seismic behavior was investigated. The infill walls with opening are seldom included in numerical analysis of reinforced concrete structural systems, since masonry panels are generally considered as non-structural components. Pushover curves are obtained for the structures using nonlinear analyses option of commercial software SAP2000. In this paper the method is summarized and applied to the deterministic seismic assessment of a one-storey reinforced concrete frame with parapet masonry infill. A comparison has been made with the behavior of the bare frame. The results yield that it is essential to consider the effect of masonry infill for the seismic evaluation of moment-resisting RC frames, especially for the prediction of its ultimate state, so we can predict actual behavior of buildings with short columns and exhibit from unrepaired shear failure phenomenon of columns.

Keywords:

RC structures , masonry infill walls , short column , shear failure , nonlinear pushover analysis