الفهرس 
LITRATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Masonry is used as a construction material all over the world. Although there is a great development in the major of the construction material, masonry still keep its popularity. URM structures is considered one of the oldest techniques that was used in ancient countries such as: Egypt, Italy and China. Most of URM buildings that exist nowadays have historical significance. They were built before the establishment of modern building codes. URM structures were constructed to bear only gravity loads and lateral loads are not considered in design. Most of these structures are still in service and their damage or collapse represents serious problem. The need to retrofit URM buildings has become one of the most priorities. Many techniques have been used to retrofit these building but apparently, they have some drawbacks. The researchers need to find a new technique that is effective, affordable, easy to apply and overcome the drawbacks of traditional techniques.
Textile reinforced mortar (TRM) is one of the recently used techniques in retrofitting URM structures. In this technique mortar used to replace the polymers that was used before with fibers. A layer of mortar is applied then the textiles are applied and then covered with another layer of mortar. Different type of fibers can be used such as: glass, aramid, steel and carbon. Basalt started to draw attention in the recent years to be used in TRM technique. Recently, Basalt was used due to its superior properties such as high strength to cost ratio and low energy consumption in manufacturing.
The main objective of this study is to investigate retrofitting of URM walls against out-of-plane loading by using the recent developed technique of BTRM. Also, one of the main objectives of this study is to develop suitable equations to be used in capacity prediction of the URM walls retrofitted with BTRM. In order to meet these objectives, experimental and analytical studies are conducted and documented in this Thesis.
This study involves two main phases. The first phase, described in research program, investigates the properties of the materials that were used later in the experimental program. The materials used in this research are masonry clay brick units, masonry mortar, basalt textiles which is applied by using retrofitting mortar as a binder (polymer modified cement mortar). Compressive strength test was performed on masonry units and masonry prisms to determine the average compressive strength (ƒ’m). Compressive strength and splitting tension tests were performed on the masonry mortar and the polymer modified mortar to determine the mortar properties. Finally, BTRM coupons were casted and tested in tension test (using pin-action test setup) to determine its tensile properties.
The second phase, presented in chapter four, focusses on retrofitting URM walls against out-of-plane loading by using BTRM technique. Fourteen URM walls were constructed (ten walls were single wythe and four walls were double wythe). Seven of them were constructed vertically (load perpendicular to bed joint) and the other seven were constructed horizontally (load parallel to bed join). The bonding material used for applying the textiles was polymer modified cement mortar. The parameters considered in this study are wall thickness (single wythe and double wythe), spanning direction (vertically spanning and horizontally spanning), textiles mesh sizes opening (5×5mm and 10×10mm), number of layers (two layers and four layers) and strengthening scheme (one side and both sides). All specimens were tested in out-of-plane flexural test under three-point monotonic loading regime with loading span equals 860mm.
5.2. Conclusions
Based on the results obtained and discussed in the previous chapters, the following conclusions can be drawn:
• The proposed technique of URM walls retrofitting against out-of-plane loading by using BTRM yielded reliable efficiency. This technique has advantages of low cost, ease of application and also overcome FRP problem with high temperatures.
• Out of plane flexural capacity of URM walls has been remarkably increased by 198% for two layers and 400% for four layers in single wythe specimens and increased by 235% to 291% for four layers in double wythe specimens when compared to the control specimens. As well as energy absorption which has been increased by 22 to 66 times for single wythe specimens and 63 to 90 times for double wythe specimens.
• Retrofitted specimens by using two layers 5×5 mm yielded an increase in capacity by 216% on average for single wythe specimens, while retrofitting by using four layers yielded an increase in capacity by 398% on average for single wythe specimens. For double wythe specimens the increase in capacity was 263% on average. Although, the double wythe specimen failed in shear failure mode due to low span to depth ratio.
• Retrofitting URM specimens by using two reinforcing layers showed higher efficiency, with respect to flexural capacity, for each layer than using four layers. It can be attributed to the irregularity in stress distribution over the textile layers. Also, by increasing number of textiles layers a reduction in bond between textiles and (PMC) mortar occurred.
• Smaller mesh size opening leads to increase in flexural capacity by 98% on average compared to larger mesh size opening, although the smaller mesh size is higher in capacity by 70%. It is attributed to better bond in smaller meshes which preformed effectively more than the larger mesh size.
• Smaller mesh size opening also showed increase in max deflection and energy absorption by 60% and 145% on average compared to larger mesh size opening.
• Spanning direction has insignificant effect on flexural capacity as the plastering mortar yields great effect in either tension or compression sides and decrease the contribution of the masonry on the capacity of the wall. While vertically spanning yielded positive effect on energy absorption.
• The retrofitting both wall surfaces yielded insignificant effect on retrofitting efficiency. Even though, retrofitting both sides of wall are recommended to resist reversible loads.
• ACI model has been modified to be more accurate in prediction of the capacity for walls. ACI model is conservative when predicting the capacity of walls retrofitted with light reinforcement. Proposed model proved good agreement with the experimental results.
5.3. Recommendations
Although this research focused on understanding the behavior of the URM when retrofitted with BTRM, additional researches still needed therefore these recommendations are suggested for further work:
• Further studies are needed to investigate the behavior of URM walls when retrofitted with BTRM to resist out-of-plane loading with different types of masonry units.
• Bond behavior of BTRM with masonry walls should be investigated in further studies.
• The effect of fiber reinforcement ratio should be well studied to have detailed modification factor for ACI model.
• Studying the effect of retrofitting of URM against in-plane loading using BTRM.
• Dynamic and cyclic out-of-plane and in-plane loading of the URM walls retrofitted using BTRM should be considered in further study.
• Detailed numerical analysis is required to understand the behavior of BTRM as a retrofitting technique for URM structures and to enlarge the information to accurately simulate using finite element analysis model.