PSI - Issue 13

Mirjana Jelić / Procedia Structural Integrity 13 (2018) 391 – 397 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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for patented technology for the remediation and protection of structures from the effects of the earthquake, invented by Zoran Petrasković . This technology is protected with five Serbian patents, four of which have been granted for inventions that were created in the 21 st century (Table 2). However, the invention from 2003, under the title: System for seismic reinforcement for structures, which is protected with patent No. RS50393B (Table 2), was also published internationaly with international publication No. WO2004097146A1, and on territory of USA and Australia with the publication No. US2006207196A1 and AU2003254327A1 respectively. This show s Petrasković 's intention of spreading the mentioned technology at the international level. Furthermore, DC90 technology was awarded by Brussels Eureka (http://dc90.co.rs/about-us.html). System for seismic reinforcement for structures from 2003 (patent No. RS50393B) was verified by experiments on various models of masonry structures carried out by the Institute for earthquake engineering and engineering seismology (IZIIS) from Skopje and the Institute for Testing of Materijal (IMS) from Belgrade (Petrašković, 2005 ). In addition, the behavior of the damper, as a key element of the aforementioned system of seismic reinforcement for structures, was verified at the Military Technical Institute (VTI) from Belgrade (Fig. 2) (Petrašković, 2005). Furtermore, this patent has been successfully applied on structures in Kolubara region in Serbia and in Algeria, and since it is applied from outside, it has proven to be a very sophisticated and effective tool in the hands of engineers to solve the problem of retrofiting of damaged structures (Petrašković, 2005).

Fig. 2. Typical dampers of the DC 90 System protected by the patent No. RS50393B and their testing (Petrašković, 2005)

Petrasković worked on the further development of the seismic energy absorbers -dampers, and in 2010 he submitted patent applications for the three types of seismic energy absorbers designed for different purposes and working conditions, and for which patent protection was granted (Table 2). In addition to this, Petrasković made a scientific contribution in the field of material fatigue, defending his doctoral thesis in 2013 at the Faculty of Civil Engineering of the University of Belgrade, on the subject: "Low-cycling fatigue of a damper-seismic energy absorber of DC 90 System under uni-axial stress". The above-mentioned doctoral thesis is based on the tests on 36 models with aforementioned seismic energy absorbers of the DC 90 System with over 50 testing programs, which were carried out in five reference laboratories (Petrašković, 2013). In addition to the aforementioned three institutes in which the damper from 2003 was tested (protected by patent No. RS50393B), new tests that included three types of dampers from 2010 (Fig. 3) were also performed in the laboratory of the Building and Geodetic Institute in Ljubljana, Slovenia, as well as in the State Institute of CGS in Algeria ( Petrašković, 2013 ). Petrašković's scientific contribution consists in broadening knowledge about the fatigue of materials from which are manufactured devices and equipment for controlling low-cyclic fatigue due to earthquake effects, as well as the behavior of this equipment in conditions of earthquake, and thus determined the parameters that define low-cyclic fatigue of the DC 90 System devices. Thus, by comparing the results of a simple sample test from a structural steel S235 and a hysteresis earthquake damper of the same material Canada HQ Royal (Fig. 4), which is protected by the patent No. RS50393B, showed that, in conditions of low-resistance fatigue, a standard steel sample lasts only 12 cycles, while the specified damper holds up to 200 cycles (Pet rašković, 2013) . Furthermore, for the needs of the investor, Hidrokvebek from Canada , Petrašković conducted "numerous, three year tests on models and structures in order to select a technical solution for adhering the 1 km long, 24 m high and 1.20 m thick wall of a machine building.", and thus he has developed two new dampers Canada HQL and Canada