unreinforced masonry buildings

A recent earthquake of M=4.9 occurred on 29 October 2007 in C, ameli, Denizli, which is located in a seismically active region at southwest Anatolia, Turkey. It has caused extensive damages at unreinforced masonry buildings like many other cases observed in Turkey during other previous earthquakes. Most of the damaged structures were non-engineered, seismically deficient, unreinforced masonry buildings. This paper presents a site survey of these damaged buildings. In addition to typical masonry damages, some infrequent, event-specific damages were also observed. Reasons for the relatively wide spread damages considering the magnitude of the event are discussed in the paper

earthquake occurred on 19 May 2011

Different levels of damages occurred in state buildings, especially in educational facilities, during the Simav earthquake (M-L = 5.7) on 19 May 2011. A site survey was carried out in the area after the earthquake, where six state buildings were examined in detail. The results of the survey showed that main reasons for the formation of damages in these buildings are the use of low strength concrete, insufficient reinforcement, inappropriate detailing, and low-quality workmanship. The investigated buildings were also evaluated by P25-rapid assessment method. The method demonstrates that two of the buildings in question are in "high risk band"; the other two fall into "detailed evaluation band", and the rest are in the "low risk band". This figure also matches with the damages observed in the site survey

in Turkey

In this study a seismic performance assessment of school buildings, which have been built in accordance with template unreinforced masonry school projects in Turkey, has been conducted. For this purpose, the most widely used three template projects have been selected. The seismic performances of these buildings have been evaluated for various earthquake levels. This evaluation has been carried out in compliance with the Turkish earthquake code entered into force in 2007. The effects of material strength and plan features on the performance of masonry school structures have been investigated within the scope of this study. It has been concluded that school buildings with template design are far from satisfying the required performance criteria. For spectral acceleration of 0.80g, which is expected in a 475 year period in the seismic Zone 1, the average exceedance ratio for life safety performance limit is more than 80% considering different material strengths. Upon evaluation of the results a building capacity index is proposed for rapid seismic assessment of masonry school buildings

connections

Strengthening of the structures with external shear walls recently has become an attractive alternative compared to conventional strengthening methods. These external shear walls can be erected either cast-in-place or by pre-casting. However, cast-in-place construction is difficult and time consuming especially in multistory buildings. On the other hand, a single precast panel is too heavy for transportation and assembly. These difficulties might be overcome by producing precast panels as multi-piece panels. However, in that case, behavior of connections between panels will be important as it could control the failure mode of the shear wall. For this reason, this study is aimed at testing the behavior of different types of precast panel connections. Within this study, one monolithic reference model and two precast panel models having anchored connection details were produced. The behavior of connections was tested under reversed-cyclic lateral loads. The results showed that ductility of the models with connections are significantly lower than monolithic specimen. Although, each panel has good RC detailing with proper confinement and concrete quality, connections are the governing elements that control the behavior. Cracking was only observed at the connection, and there were no proper plastic hinge formations at the panels. Therefore, it was concluded that anchored connections cannot be designed for high ductility levels. Some suggestions are made regarding the area of use of anchored connections in precast panels

shear walls

The strengthening of reinforced concrete (RC) structures with external steel shear walls was investigated in this study. The proposed technique allows the strengthening of in-service RC structures in parallel to reducing the construction costs and leading to faster and more workable solutions. The experimental program includes three-dimensional RC models, which exhibited some of the structural deficiencies commonly encountered in existing RC structures. The related tests were conducted under the imposed reversed cyclic lateral sway. Accordingly, performance of the proposed strengthening technique is found to be adequate for improving the seismic capacity of existing RC structures. Additionally, base shear capacity and stiffness of the strengthened model were significantly improved. (C) 2011 Elsevier Ltd. All rights reserved