In plane seismic strengthening of brick masonry walls using rebars

Erdoğdu, Murat
About half of the total building stock in Turkey is masonry type building. Masonry buildings in Turkey, especially in rural areas, are constructed without any engineering knowledge mostly by their own residents. They generally have heavy roofs. Masonry type buildings also have thick and heavy wall materials. Heavy roof and wall material generate large inertial forces in the case of an earthquake. Brittle failure of walls leads to total failure of whole system followed by sudden collapse of heavy roof. The aim of this thesis is to understand failure mechanisms of brick masonry walls, prevent their brittle failure and allow the walls to dissipate energy during an earthquake. Furthermore, ultimate capacity increase was also targeted by using low cost and easy to obtain material. In order to find an economical and effective way in strengthening of brick masonry walls in their in-plane direction, steel rebars were used as post-tensioning materials in brick masonry walls and house tests. Springy connections were utilized in the reinforcing and post-tensioning bars in order to prevent early loss of post-tension due to wall cracking or rebar yielding. Separate tests were conducted with and without rebars and springs in order to compare their results. v The test results indicated that the ultimate lateral load capacity of 6m long brick masonry house increased up to about 6 times with respect to its nominal value. Energy dissipation also increased up to about 10 times of the original house. Lateral load capacity increase in 2m long rebar post-tensioned brick masonry walls were measured as about 17 times when compared with the original wall. The energy dissipation capacity was also increased about 30 times the nominal value. A general procedure was developed to assess the vulnerability of single storey masonry houses, which calculates the earthquake demand acting on each wall segment. Comparison of capacity versus demand enables evaluation of wall segments and leads strengthening calculations if necessary. Derived formulas were used to calculate post-tensioning force and design vertical and diagonal rebars. The procedure was demonstrated using properties of an existing house and strengthening cost was found to be about 10% of the building cost. The results of the conducted tests have shown that rebar post-tensioning of brick masonry walls is an effective and cost-efficient way of strengthening the walls in their in-plane direction and can be used as an economical and simple technique for seismically vulnerable masonry houses. Spring based connection detail has improved the post cracking performance of the walls at large deformations by keeping the wall reaction higher after ultimate strength has reached as well as increased the energy dissipation capacity of the walls.


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Citation Formats
M. Erdoğdu, “In plane seismic strengthening of brick masonry walls using rebars,” M.S. - Master of Science, Middle East Technical University, 2008.