Dr Yuri Totoev

The threat to human lives and the economic losses due to high seismic vulnerability of non-engineered traditional masonry infills subjected to earthquakes have been highlighted by several post-seismic surveys and experimental and numerical investigations. In the past decades, researchers have proposed different techniques to mitigate problems related to the seismic vulnerability of traditional masonry infills; however, a viable, practical, and universally accepted solution has not been achieved yet. Among the possible innovative techniques, the one using ductile (or pliable) infills have shown promising results in recent experimental tests. These infills have provided, indeed, a reduced in-plane stiffness and a very high displacement capacity. The research units of the University of Pavia/EUCENTRE (Italy) and the University of Newcastle (Australia) have proposed two different systems for ductile masonry infill based on dividing the masonry panel into a number of segments interconnected through horizontal sliding joints. The ductile masonry infill proposed by the University of Pavia subdivides the masonry panel into four horizontal subpanels using specially engineered sliding joints and presents a deformable mortar at the infill/structure interface, while the one conceived by the University of Newcastle is made of mortar-less specially shaped masonry units capable of sliding on all bed joints. The experiments conducted on the two novel systems have permitted the calibration of two numerical macromodels capable to replicate the overall in-plane seismic response of these ductile masonry infills. One approach is based on a spring model, as usually adopted for traditional masonry infill; the other calibrates the response of a semi-active damper model. The calibrated macromodel approaches have been adopted to demonstrate the enhanced behavior and the reduction of the seismic vulnerability of reinforced concrete (RC) framed structures with the employment of the ductile infills in comparison to structures with non-engineered masonry infills.

The Semi-Interlocking Masonry (SIM) system has been developed by the Masonry Research Group at the University of Newcastle, Australia. The main purpose of this system is to enhance the seismic resistance of framed structures with masonry panels. In this system, SIM panels dissipate energy through the sliding friction between rows of SIM units during earthquake excitation. This paper aimed to find the applicability of artificial neural networks (ANN) to predict the displacement behaviour of the SIM panel under out-of-plane loading. The general concept of ANN requires them to be trained by related force-displacement data of SIM panels. The overall data for the training and testing of the network was 70 increments of force-displacement from three tests, which comprise of nine input nodes, these being height and length of panels, height, length and width of the brick, friction, geometry angle of brick, compressive strength of the brick with the lateral load. The aim of this study is to predict the displacement of the SIM panel using the Radial Basis Function network (RBF). The mean square error (MSE) of the network was 0.00032 and the coefficient of determination (R2) values showed as 0.96. The result revealed that ANN has significant potential to predict the behaviour of SIM panels.

The behavior of dry stack masonry (DSM) is influenced by the interaction of the infill with the frame (especially the joints between bricks), which requires further research. This study investigates the compression and shear behaviors of DSM. First, a series of compression tests were carried out on both masonry prism with mortar (MP_m) and DSM prism (MP_ds). The failure mode of each prism was determined. Different from the MP_m, the stress-strain relationship of the MP_ds was characterized by an upward concavity at the initial stage. The compression strength of the MP_ds was slightly reduced by 15%, while the elastic modulus was reduced by over 62%. In addition, 36 shear-compression tests were carried out under cyclic loads to emphasize the influence of various loads on the shear-compression behavior of DSM. The results showed that the Mohr-Coulomb friction law adequately represents the failure of dry joints at moderate stress levels, and the varying friction coefficients under different load amplitudes cannot be neglected. The experimental setup and results are valuable for further research.

In order to increase the energy dissipation of wall/frame elements subjected to in plane shear loading a conceptually new system for masonry infilled RC frame has been proposed and proved as effective. The interaction between frame and infilled panel is considered as the major cause of the nonlinear behavior of structure. In this paper, the experimental results are briefly summarized and a micro finite element model is developed to simulate the monotonic response of the masonry infilled structure. A novel type of element called "initial gap element" is presented to simulate the gap between the frame and panel to allow the continual simulation of the response for the full load cycle. All the material parameters are experimentally evaluated. The initial testing included free vibration and cyclic tests on a bare RC frame followed by cyclic test on the RC frame infilled with a dry-stacked concrete brick panel. These results are used to verify the accuracy of the model. It is shown that the model is able to simulate the failure mechanisms exhibited by experiment including the crushing and cracking of the concrete frame and the diagonal compressive stress contribution of the masonry panel. The load-displacement response predicted by the model was also in good agreement with that obtained from the tests. Furthermore, the model was used for ultimate analysis, which discovered four typical stages of structural response of the dry-stack infilled RC frame and found the friction between bricks in the dry-stacked panel contributes significantly (about 50%) to the assembly. © 2014 Politechnika Wroclawska.

The semi-interlocking masonry (SIM) system has developed in Masonry Research Group at the University of Newcastle, Australia. The SIM panels dissipate energy through the sliding friction on bed joints of SIM units during earthquake excitation. To model the SIM panel's behaviour numerically some key parameters need to evaluate experimentally. This study investigates the elastic modulus of SIM prism and thrust force for horizontal and vertical arching during out-of-plane deflection. Three types of bricks were used in tests: topological SIM, mechanical SIM, and without interlocking bricks. In addition, the prisms of topological SIM bricks comprising three and five bricks have been used to find out the mechanical properties of units. This paper presents the results of 18 arching tests: six tests with topological interlocking, six tests with mechanically interlocking units, six tests with ordinary bricks, and 11 prisms of topological SIM bricks for compressive and modulus of elasticity test.

Many post seismic event inspections and studies conducted by different researchers have identified the threat to human lives and considerable economic losses related to the damage sustained by ¿traditional¿ masonry infills. Although several innovative infill solutions and new design approaches have been proposed, a viable practical and universally accepted solution has not been achieved yet. Among the very promising designs, according to the ongoing studies, are pliable infill panels with the in-plane stiffness reduced and the displacement ductility increased compared to ¿traditional¿ infills. One way to attain such a significant pliability of a masonry infill is to divide it into a number of segments interconnected through horizontal sliding joints. The research units at the University of Newcastle (Australia) and the University of Pavia have proposed and are studying two different infill systems of this type: one mortar-less made of specially shaped masonry units capable of sliding on all bed joints; another with infill masonry panel subdivided into several horizontal sub-panels using specially engineered sliding joints. Within this paper, two systems are compared and discussed with particular emphases on their basic dynamic characteristics required for seismic analysis.

This study experimentally investigated water penetration through semi-interlocking masonry (SIM) walls using a standard test methodology. The main objective of this study was to investigate the water-penetration performance of dry-stacked SIM walls and the effects of using gap-fillers on the testing walls. The performance of a traditional unreinforced masonry wall was used as the benchmark against which the results for SIM walls were compared. This paper reports the water-penetration performance results of several types of SIM walls investigated in this study.