engleski

Seismic evaluation of three story masonry infilled reinforced concrete frame model structure

Unrealistic or inadequate assessment of buildings may not identify the true failure modes, leading to unsafe designs or may produce overly conservative retrofits where none is needed to meet the desired performance objective. Therefore, more sophisticated methods that consider both the actual loading and inelastic response buildings experience should be used. This paper provides a performance based seismic evaluation of existing masonry infilled model concrete building. It is performance based: the evaluation and retrofit design criteria are expressed as performance objectives, which define desired levels of seismic performance when the building is subjected to specific levels of seismic ground motion. So, the approach used in this paper is somewhat reverse: it starts with the observed/measured performance of test building subjected to series of shake table tests. The model structure is a three-story, 1:2, 5 scaled reinforced concrete frame building with masonry infill walls subjected to ground motions of increasing intensity in two series. First hollow masonry units were used. After completion of tests, the structure was repaired by replacing hollow masonry units with new solid units. Reinforced concrete end elements were also added along the vertical edges of window and door openings in the first and second stories. The repaired structure was then tested with the same sequence of base motions. The objective of this second test series was to investigate whether the repaired, framed- masonry system would have sufficient capacity to sustain the applied earthquake demands. Acceptable performance is measured by the level of structural and/or non-structural damage recorded during the earthquake shaking. Once the resulting performance of the test building using the acceptability criteria is defined, the performance point for a demand earthquake is checked. The performance is checked on two levels. First, there are global limits for displacement of the structure for each performance objective. Similarly, individual structural elements were checked against acceptability limits which depend on the global performance goal. The entire process of generating the capacity curve and dealing directly with the interdependence of capacity and demand gives a greatly enhanced understanding of the actual performance of the specific building. This enables the engineer to apply the necessary experience and judgment at a much more refined level then traditional procedures.

seismic evaluation ; performance ; rc masonry infilled frame building ; shake table test ;

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