Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- Shear Behaviour (2) (entfernen)
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The paper presents a comparison between different numerical modelling ap-proaches aiming to simulate the in-plain behaviour of three types of earthen materials, name-ly adobe masonry, rammed earth and cob. For this purpose, uniaxial and diagonal compression tests were carried out, which allowed determining important mechanical param-eters, such as compressive strength, Young’s modulus, Poisson’s ratio, shear strength and shear modulus. Furthermore, the tests allowed assessing the level of non-linear behaviour of the respective stress–strain relationships as well as the failure modes. The experimental results were then used for the calibration of numerical models (based on the finite element method) for simulating the non-linear behaviour of the earth materials under in-plane shear loading. Both macro- and micro-modelling approaches were considered for this purpose. The procedures adopted for model calibration established the reliability of various modelling strategies for the different loading conditions. The simplified approach based on macro-modelling shows a satisfactory accuracy and low computational costs. The results reproduc-ing the uniaxial compression are in good correspondence with the post-elastic behaviour ob-served in the experimental campaign. The micro-modelling approach adopted to reproduce the shear behaviour, even with higher computational cost, represents a suitable tool to pre-dict the adobe masonry and rammed earth collapse mechanisms
An experimental investigation was carried out to study the in-plane shear behaviour of rammed earth structural elements strengthened with polyester fabric strips. The original idea for the retrofitting with polyester fabric strips was to introduce a vertical element for walls in order to take up horizontal loads resulting in a shear response of the building element. It has to be considered that vertical slits into the walls for fixing the strips are points of weakness and have to be mitigated by the adhesive. In this case a base coat mortar was employed. Strengthened elements were tested to exploit the strength potential of earthen materials and to solve its lack of tensile strength, significantly improving not only strength but also ductility. As part of the study results of a testing campaign of unstrengthened structural elements were considered. Strengthened elements were tested in diagonal compression/shear and cyclic shear-compression. A unique reinforcement orientation was used. The results of these tests are presented in this paper and include the load-displacement behaviours, crack patterns, failure modes. The results showed that the reinforcement was the most effective under cyclic shear-compression tests, with increase in load and displacement capacity observed. Under diagonal compression the reinforcement did not likely contribute significantly to the shear resistance, due to a lack of embedment length of the strips.