Yuri Z. Totoev

AN INFILTRATION MODEL TO PREDICT SUCTION CHANGES IN THE SOIL PROFILE

A computer model for the infiltration at the soil surface is described. The model has been developed for computation of seasonal suction changes in the soil profile. It simulates time dependence of the vector of sources and sinks for the finite element solution of Richards equation. Lumped meteorological and soil parameters are used. Meteorological input to the model consists of the records for rainfall, pan evaporation, air temperature, and air humidity. As an example of an application of the model, the daily magnitudes of infiltration/evapotranspiration at the soil surface at Maryville, New South Wales, Australia, in March and April 1993 were obtained, and the resulting suction profile was calculated numerically. This example shows that the model adequately reflects major meteorological changes. The resulting suction profile correlates well with the experimental data, better than profiles resulting from the models, which assume periodic or sudden changes in surface suction.

In-Plane Cyclic Test on Framed Dry-Stack Masonry Panel

A new masonry system has been developed to improve the seismic behaviour of RC frame with masonry panels. In this system dry-stack masonry panels are built with masonry units capable of sliding in-plane of a panel. These masonry panels have reduced in-plane stiffness but increased frictional energy dissipation capacity compared with the traditional masonry panels. Under seismic or wind loads these panels do not detrimentally interfere with natural RC frame response but rather positively contribute to it mainly by increasing dumping. A cyclic test has been performed to evaluate the behaviour of this masonry system. Test results demonstrate that the new system can improve the seismic behaviour of RC frame structures with masonry panels.

Experimental Characteristics of Dry Stack Masonry under Compression and Shear Loading

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-Plane Behaviour of a Reinforcement Concrete Frame with a Dry Stack Masonry Panel

In order to improve the energy dissipation of the masonry infilled frame structure while decreasing the stiffening and strengthening effects of the infill panels, a new dry stacked panel (DSP) semi-interlocking masonry (SIM) infill panel has been developed. In this paper, the material properties of DSP and a traditional unreinforced masonry (URM) panel have been evaluated experimentally. A series of cyclic tests were performed to investigate the cyclic behaviour of the reinforcement concrete (RC) frame with different infill panels. The failure modes, damage evolution, hysteretic behaviour, stiffness degradation and energy dissipation were compared and analysed. We concluded that DSP is capable of significantly improving the seismic energy dissipation due to its hysteretic behaviour when the frame is in elastic stage without increasing the stiffness of the frame. Therefore, DSP or SIM panels can be considered as frictional dampers. Based on the experimental results, the influence of DSP was examined. Using the parallel model, the hysteretic loops of DSP subjected to different load cases were achieved. The typical full hysteretic loop for DSP could be divided into three distinct stages of behaviour: packing stage, constant friction stage and equivalent strut stage. The connection between the panel and the frame had a great effect on the transferring of different mechanical stages. The constant friction stage was verified to provide substantial energy dissipation and benefits to the ductility of the structure, which, therefore, is suggested to be prolonged in reality.

Earthquake shear load in load-bearing masonry buildings

Abstract Load-bearing masonry buildings are composed of concrete slabs and supporting masonry walls, and in Australia usually incorporate slip joints in the interfaces between walls and slabs for serviceability reasons. The apparent conflicting requirements of the slip joints, to slip under long-term loads and to transmit short-term loading from wind and earthquake actions, together with the lack of attention to the design of slip joints, make slip in the joints likely to occur when the building is subjected to a lateral loading. Joint slip leads to a redistribution of loading in the building wall system, resulting in wall shear loads different from that determined using the current standard elastic design procedures. Redistribution of loading may be also caused by softening of the masonry. This paper has assessed the realistic response of various load-bearing masonry buildings, including the potential for slip in the joints and softening of the masonry, and evaluated the level of wall shear load deviations resulting from the application of current design procedures. Analyses of the buildings, using non-linear static and dynamic finite element models, have indicated that joint slip may occur in buildings subjected to earthquake loading. The application of current elastic design procedures, which do not account for loading redistribution, resulted in major wall shear load deviations, such as overestimations of up to +75% and underestimations of up to-62%. It was therefore concluded that improvements in the current design procedures are required for a more accurate evaluation of wall shear loads in load-bearing masonry buildings subjected to the lateral loading.

The influence of ribs stiffness and shape imperfections on stability of a ribbed folded plate structure

Abstract The stability of a ribbed thin-walled folded plate structure with various ribs stiffness and geometrically imperfect shape has been considered, in addition to the static and dynamic external load. The stability problem has been solved by a numerical algorithm, which is based on the reduced basis method. This algorithm uses the finite difference technique for the numerical approximation of the geometrically non-linear equations of motion of the general theory of thin shells. The vectors of the reduced basis are generated automatically and are used as modes of displacement of the structure to reduce the finite difference model. The critical loads have been determined for structure with different stiffness of ribs. The influence of the shape imperfections of the structure on its static and dynamic stability also has been studied.

Experimental Investigation of Water Penetration through Semi-Interlocking Masonry Walls

AbstractThis 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.