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The seismic strengthening of buildings in earthquake-prone areas has been a hot topic in recent years, especially for masonry structures. Because there are so many masonry structures and because most were built before seismic codes existed, their seismic vulnerability is an unavoidable issue. Over the years, several methods for seismic strengthening of masonry piers and walls have been developed that may roughly be classified as traditional or modern. In this paper, an overview of the most commonly used and effective methods will be presented with an emphasis on modern methods based on a Fabric-Reinforced Cementitious Matrix. The advantages and disadvantages will be discussed from the point of view of usability, feasibility, and effectiveness. Finally, a comparison will be drawn between traditional and new methods based on composite materials. [ABSTRACT FROM AUTHOR]

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The efficiency of strengthening of unreinforced hollow clay block masonry buildings with fibre reinforced mortar coatings has been investigated. A full scale three-storey building model and a series of accompanying walls have been built and tested. Reference unstrengthened, and strengthened specimens of each type have been tested by subjecting them to cyclic shear at constant compressive load. First, the three-storey model was tested in its original state until the maximum resistance was attained and major, but still repairable damage, developed in the walls. Then, the damaged model was strengthened with fabric reinforced cementitious mortar coating and re-tested up to near collapse limit state. Typical storey mechanism was observed in original and strengthened state, with the majority of damage concentrated in the walls of the bottom storey. Diagonally oriented shear cracks prevailed in the elements in the direction of loading. The behaviour of single walls in cyclic shear tests was similar to that observed in the piers of the building models. The analysis of test results indicated that the resistance and displacement capacity of unreinforced masonry structures of the particular type tested can be significantly improved if delamination and separation of coating is prevented. Finally, a calculation model for the assessment of seismic resistance of reference and strengthened building model is presented and the comparison between calculated and experimental results discussed. [ABSTRACT FROM AUTHOR]

This paper is aimed at investigating the usage of flexible joints in masonry infilled walls surrounded by reinforced concrete (RC) frames. For this purpose, a real-size specimen was numerically created and exposed to the seismic loads. In order to evaluate both in-plane and out-of-plane performances of the infill walls, the system was chosen as a box shaped three-dimensional structure. In total, three different one-story constructions, which have single bays in two perpendicular directions, were modeled. The first type is the bare-frame without the infill walls, which was determined as a reference system. The second and third types of buildings are conventional mortar joint and PolyUrethane Flexible Joint (PUFJ) implemented ones, respectively. The influence of these joints on the material level are investigated in detail. Furthermore, general building dynamic characteristics were extracted by means of acceleration and displacement results as well as frequency domain mode shapes. Analyses revealed that PUFJ implementation on such buildings has promising outcomes and helps to sustain structural stability against the detrimental effects of earthquakes. [ABSTRACT FROM AUTHOR]

• Dynamic tests of a typical façade fastening system in RC precast structures. • The failure criterion of the fastening system is identified. • New numerical models for connections are proposed and validated by dynamic tests. • The typical values of model parameters are proposed. The paper presents experimental and analytical studies of the dynamic in-plane response of typical fastening systems for horizontal cladding panels in RC precast industrial buildings in Central Europe. The system consists of two main parts: a pair of top bolted connections, which provide the horizontal stability of the panel, and a pair of bottom cantilever connections, which support the weight of the panel. A typical response mechanism of the fastening system consists of three distinct stages: sliding with limited friction, contact with the panel causing an increase in the connection stiffness, and failure. It has been found that the capacity of the complete system is limited by the displacement capacity of the top connections, which are the most critical components. Therefore, it is better to express the capacity of the entire system in terms of displacements. Appropriate numerical models for the complete fastening system have been proposed and validated by the results of the presented experiments. The top and bottom connections were analysed separately and showed physically different response behaviours. The typical Coulomb friction model was used to describe the friction in the top connection, whereas the viscous friction model better simulated variable friction in the bottom connection. The contacts that occur when the gap for sliding of panels closes were simulated by an abrupt increase of the stiffness of the connection. [ABSTRACT FROM AUTHOR]