RETROFITTING OF MASONRY WALLS
مولف یا نویسنده:
Iman elyasian structural engineer
چاپ و انتشار:
Existing masonry buildings around the world, many of which are of historical and architectural value, may not have adequate resistance against seismic and wind loads. In the following sections some studies on masonry walls retrofitted with conventional methods and with FRP composites are briefly described.
RETROFITTING, MASONRY WALLS, FRP
The use of FRP composites for the retrofitting of masonry structures offers some advantages compared to the use of conventional retrofitting techniques. As an example, FRP composites do not add considerable mass to the structure. This extra weight could modify the dynamic response to seismic events, which may be observed when using masonry- RC composite walls or ferrocement overlays. From the architectural point of view, the use of conventional methods may violate the aesthetics of building facades and they may intrude on usable space adjacent to the strengthened components. The aforementioned facts along with the outstanding properties of FRP materials make the use of FRP composites attractive for strengthening of masonry structures. Studies on masonry walls strengthened with FRP composites have shown that increases in either out- of- plane or in plane capacities as well as ductility can be achieved. However, most of these studies have been carried out in laboratories, under ideal conditions such as considering free rotation of the supports. In this sense, some tests performed in this investigation offered an opportunity to observe the behavior of masonry walls under real boundary conditions, which are not commonly reproduced in the laboratory.
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چند خط متن:
Hamid (1996) conducted an investigation aimed at strengthening of hollow concrete block walls using, similar to basement walls. As a vertical reinforcement # 4 FRP rods were used to strengthen a URM wall because of their corrosion resistance and ease of installation. The strengthening procedure consisted of: (1) cutting slots at the top course of the wall to place the reinforcing bars, (2) inserting the rods, (3) drilling holes of 2- in. diameter thorough the height of the cells to pump the grout; and (4) pumping grout starting from the lower holes; plug the holes after grouting to continue with the upper holes. The 4 by 8.5-ft. walls were simply supported and tested under out-of- plane loading. In the strengthened wall, a 22-fold increase in flexural capacity compared to the unstrengthened wall was recorded. In addition, a large deformation capability beyond the first crack was observed, as seen in Figure ۱۳. This is attributed to the presence of the reinforcing bars and the high tensile strength of the grout.