Browsing by Author "Gulkan, Polat"

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    Numerical Assessment of Cracks on a Freestanding Masonry Minaret
    (2019) Kazaz, Ilker; Gulkan, Polat; Kazaz, Emriye
    The Minaret of the Sheikh Mutahhar Mosque was constructed in the beginning of sixteenth century. It is located in Diyarbakir, a city with moderate seismicity in Turkey. Although it has survived for five centuries, the tower is seemingly vulnerable to ground movements, because the minaret body simply stands freely on four cylindrical stone columns. A description of this special structure is provided. In recent years significant cracks have developed in two of the main lintels at the base of the minaret. The square cross-section minaret may be used as an ersatz, large-size seismograph, to examine the possible upper limits of seismic action that must have affected it without leading to overturning and stressed it beyond its strength to develop the observed cracks. Seismic response of the minaret is investigated through a numerical model generated using an explicit finite element code. The frictional contact behavior between stone units is included in the model and used to estimate the inherent damping. The 3D nonlinear finite element model results are compared with results of rocking rigid block model. It appears that the amplitude of the ground motion at the site did not exceed 0.15 g during the 500 years life span of the minaret.
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    Tie system to upgrade out-of-plane performance of infill masonry walls
    (Başkent Üniversitesi Mühendislik Fakültesi, 2024-02-20) Choi, Ho; Nakano, Yoshiaki; Sanada, Yasushi; Matsukawa, Kazuto; Gulkan, Polat; Binici, Baris
    The objectives of this study were to investigate the out-of-plane behavior of unreinforced masonry (URM) infill walls and to identify the effectiveness of tie systems that were proposed to enhance the infill stability under both in- and out-of-plane effects. This study examined three types of tie systems: a full-length tie system (prototype), a staggered tie system and a half-length tie system. For this purpose, four 1/4-scale, single-story, one-bay masonry infilled reinforced concrete (RC) frame specimens with and without the proposed tie systems were sequentially tested under in-plane static cyclic loading and out-of-plane dynamic excitation. In the experimental study, two series of shaking table tests were conducted to investigate the out-of-plane behavior of the infill walls. The first series compared the fundamental out-of-plane performance of three proposed tie systems, and the second series verified the effectiveness of the full-length tie system to prevent infill out-of-plane failure under an excitation simulating the severe floor response in medium-rise buildings. The test results indicated the following: (1) the presence of the tie systems caused minor differences in the in-plane capacity and ductility of each specimen, (2) the effectiveness of the full-length and staggered tie systems was superior to that of the half-length tie system, and (3) the full-length tie system not only prevented the infill out-of-plane failure but also significantly reduced the infill damage under realistic excitation conditions. The above research outcomes provide a useful contribution of the infill to upgrade the seismic resistance of buildings.