Abstract. During the last earthquakes in Turkey, reinforced concrete structures in the cities and masonry structures in the rural part were exposed to damage and failure. Masonry houses such as earthen, brick and stone structures are composed of building blocks with weak inter-binding action which have low tension capacity. Bending and shear forces generate tensile stresses which cannot be well tolerated. In this paper, the performance of masonry structures during recent earthquakes in Turkey is discussed with illustrative photographs taken after earthquakes. The followings are the main weakness in the materials and unreinforced masonry constructions and other reasons for the extensive damage of masonry buildings. Very low tensile and shear strength particularly with poor mortar, brittle behaviour in tension as well as compression, stress concentration at corners of windows and doors, overall unsymmetry in plan and elevation of building, unsymmetry due to imbalance in the sizes and positions of walls and openings in the walls, defects in construction such as use of substandard materials, unfilled joints between bricks, not-plump walls, improper bonding between walls at right angles etc.
Abstract. The aim of this paper is to report on an experimental study about Turkish Earthquake Code on suggested strengthening method. The proposed method uses existing brick infill walls and the strengthening is done with the application of external mesh reinforcement and plaster. 5 nonductile 1/2 scaled, one bay, two storey RC specimens were tested under a reversed cyclic loading. The first two specimens were reference specimens and the other ones were strengthened with the proposed method. The specimens contained several design and construction mistakes such as low concrete quality and improper steel detailing. Strength, stiffness and storey drifts of the test specimens were measured. The results of the test on these frames were compared with the reference specimens. The effects of the reinforced mesh plaster application for strengthening on behaviour, strength, stiffness, failure mode and ductility of the specimens were investigated. Unexpected failure modes were observed during the testing and the results were summarized in this paper.
There are some problems and weaknesses related to cement-based materials, such as their very low tensile strength, low chemical resistance and the huge contribution of cement production to industrial CO2 emissions. One possible method to reduce the impacts of such problems is the partial replacement of cement in cementitious materials with nano materials. This work provides a detailed review of incorporation of one of the most widely used nano materials, namely nano-titanium dioxide, and its effect on the properties of cementitious composites. Different properties have been considered in the current study, such as fresh properties, mechanical properties (compressive strength, split tensile strength and flexural strength), durability (permeability, ultrasonic pulse velocity (UPV), electrical resistivity, carbonation resistance, freeze and thaw resistance and sulfate attack resistance) and microstructural properties. This paper also investigates the optimum content of nano-TiO2 in cement-based materials. Moreover, the cost effectiveness of use on nano-titania in cementitious composites has been discussed. Nano titania reduces the workability and setting time of cement-based materials. It can be very effective in improving the mechanical properties, durability and microstructural properties of cementitious composites.
Abstract. Most of historical buildings are built with pressure principle and have the characteristics of masonry structures. Therefore, the structure components of buildings are constituted bearing walls, columns, buttresses, vaults and domes. Natural stone, cut stone, rubble stone brick or alternate materials were used in the bearing elements. Brick-dust and mortar with more binding feature were used as combination elements. In time, some problems were occurred in used materials and in structure as a result of various effects. Therefore, it is necessary to apply various applications in framework of repair and strengthening of buildings. In this study, restoration of historic buildings and the control of the adequacy of the bearing systems as one most important part of structure were examined. For this purpose, static analysis of Edirne-Merkez Demirtaş (Timurtaş) mosque located in Edirne was tested. Testes could give suggestions and be applied if buildings needed be revealed. The structure was modelled with finite element model of sap2000 package program and the forces generated under various loads and stresses, the occurred deformation due to that, overflow of allowable stress of this deformation and stresses were investigated. As the results of this study can be note that the maximum compressive stress at the construction is calculated as 1.1 MPa.
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