A PROCEDURE TO IDENTIFY THE TYPE OF MASONRY INFILL WALLS IN FRAMED STRUCTURES BASED ON FAST AMBIENT VIBRATION TESTS

Infill and partition walls are generally used in building as enclosure elements and for separating internal spaces and are proved to be vulnerable out-of-plane leading to life-safety hazard in case of seismic events. Moreover, in earthquake prone areas it has been proved that they may significantly affect the global behavior of buildings. Therefore, their stiffness and strength should be considered in the numerical models for the assessment of reinforced concrete structure. However, for an existing building, in case of lack of design documentation, it is difficult to define visually which is the type of infill wall or partition whether single or multi-leaf as well as to determine the type of masonry with which they are made that is: blocks with horizontal holes, solid blocks, hollow clay bricks, etc. The aim of this paper is to define a methodology that allows to trace the type of masonry infill wall or partition, starting from the value of the experimental frequency obtained through fast non-destructive tests. The detection procedure is basically based on a comparison between experimental data obtained from an ambient vibration test and the numerical results obtained from an extensive parametric analysis of the most common types of masonry infill walls and partitions. The proposed methodology is validated through an application to a real reinforced concrete frame building. It is proved that it is capable to provide a very accurate estimate of the type of infill if the fundamental out of plane frequency is known from a fast ambient vibration test.