•Diagonal compression testing of 10 walls retrofitted with 3 different TRM solutions.•Basalt grid, steel textile and NSM stainless steel rebars embedded in lime mortar.•Symmetric and asymmetric TRM ...configurations are considered for retrofitting.•Two walls tested again after repair with restoration lime mortar and basalt textile.•TRM systems provide increase of ductility and strength compared with URM walls.
This paper presents an experimental study of the structural behaviour of masonry walls retrofitted with Textile Reinforced Mortar (TRM) to improve their in-plane shear strength and deformation capacity. The experimental programme consists in diagonal compression testing of ten specimens of clay brick and lime mortar masonry retrofitted with three different TRM systems: i) continuous bidirectional grids of basalt TRM, ii) discrete bands of unidirectional steel TRM and iii) continuous basalt TRM on the wall’s inner face and bed joints structural repointing with near surface mounted helical stainless steel bars on the wall’s outer face. Two of the specimens were tested two times, i.e. in the unreinforced condition and subsequently in the repaired configuration including basalt TRM retrofitting. The experimental results show that the adopted TRM solutions produce a beneficial increase of shear resistance and ductility, making them suitable for seismic retrofitting and post-earthquake repair.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Seismic behavior of masonry walls has been heavily investigated, especially by means of laboratory experiments employing cyclic tests to determine the mechanical parameters and seismic capacity. ...Nevertheless, the dynamic properties of the tested walls often remain unknown, even though the nature of the seismic response is dynamic and profoundly affected by the structure's dynamic properties. This paper presents an investigation on the dynamic properties of three different masonry wall panels in healthy and damaged states, and examines if damage quantification via tracking the changes in dynamic properties is feasible. Ambient vibration and impact measurements are used for the dynamic identification of wall panels, before and after they are tested in reversed-cyclic in-plane shear-compression tests. The natural frequencies, damping ratios, and mode shapes of the walls are determined and compared to each other. Moreover, the damage progression and its effect on the dynamic features of the URM wall panel is investigated using a discrete element model of the benchmark wall that is validated in terms of the force-displacement response and damage pattern of the wall. The results of the study indicate that changes in natural frequencies and mode shapes are traceable, although it is difficult to infer damage quantification relationships from these changes. The outcomes of this study also highlight that numerical models verified with the nonlinear quasi-static behavior do not necessarily match the wall's dynamic behavior, and that more research is required to update nonlinear numerical models. Overall, the results contribute to the knowledge regarding the dynamic characteristics of masonry walls in healthy and damaged conditions, and to quantify the damage in masonry walls as well as the changes in their dynamic properties.
•Cyclic shear-compression tests on three stone masonry wall panels.•Dynamic identification in healthy state and after damage.•Effects of damages on the dynamic properties of the walls.•Effects of strengthening on the dynamic properties of the walls.•Numerical investigation of modal properties in healthy and damaged states.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Diagonal compression tests on double-wythe Flemish bond masonry walls are presented.•Simulation of the diagonal compression test with an enhanced continuum FE model.•The diagonal compression test is ...interpreted in the linear and nonlinear range.•A coefficient of 0.4 is found adequate to compute the tensile strength of masonry.•The coefficient shows little sensitivity to panel size and size of loading shoes.
The masonry tensile strength and shear modulus play a key role in the definition of the shear capacity of masonry structures. These properties are often determined experimentally by means of the diagonal compression test on square walls, which is regulated by the ASTM E519 standard. In spite of its wide use, the interpretation of the test is still controversial and no universal criterion exists on how to derive the masonry mechanical properties from the wall overall strength. Aiming to contribute in the improvement of the test’s reliability and interpretation, this paper presents an investigation on the use of the diagonal compression test to characterise the shear properties of masonry. First, an experimental campaign on brickwork walls is described. The walls were built in laboratory in Flemish bond, a pattern that has been scarcely investigated in the available research studies on this type of test. Second, an advanced numerical model is used for the analysis of walls subjected to the diagonal compression test. The adopted numerical model, enhanced by a crack-tracking algorithm to reproduce accurately the tensile damage localization, constitutes a very useful and powerful tool to interpret correctly the behaviour during the test. Finite element analysis was executed to interpret the walls’ response in the linear and nonlinear ranges with models properly calibrated by comparison with the experimental results. As a result, a criterion was determined for the calculation of the tensile strength from the outcomes of the diagonal compression test. A sensitivity analysis was carried out with regard to the most influent material properties of the material, the geometrical dimensions of the panel, and the loading conditions of the testing setup. The findings of this research were finally applied and validated by means of simulations of diagonal compression tests from eight experimental campaigns performed by other authors on different masonry typologies.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper reports an experimental programme on masonry walls composed of handmade solid clay brick and hydraulic lime mortar. Reversed cyclic shear compression tests were carried out on the walls in ...three different configurations: unreinforced, repaired and retrofitted, and just retrofitted. Damaged walls were repaired and retrofitted with Basalt Textile Reinforced Mortar (B-TRM) and tested again to investigate the recovery of strength, stiffness and the improvement in drift capacity. The repair consisted in filling the open cracks and replacing the damaged bricks by following the so-called “scuci-cuci” technique. The just retrofitted configuration consisted of externally bonded B-TRM on undamaged walls. The B-TRM system comprised continuous bidirectional grids of basalt fibre embedded in hydraulic lime mortar on both surfaces of the walls. The experimental results showed the suitability of the proposed solutions for seismic retrofit and post-earthquake repair of existing masonry buildings. The research results highlighted the capacity of the proposed repair technique to reinforce damaged walls and the effectiveness of the investigated B-TRM system in increasing the resistance, the ductility, and the energy dissipation of unreinforced clay brick masonry. In addition, the results allowed a better understanding of the behaviour of masonry walls subjected to cyclic horizontal displacement in terms of failure mechanism and displacement capacities.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A novel damage continuous micro-model for masonry shear walls is presented.•A novel bi-dissipative damage model able to represent dilatancy of mortar joints.•The proposed micro-model is validated ...and compared to others available in literature.•Results are critically discussed and compared.
A novel damage mechanics-based continuous micro-model for the analysis of masonry-walls is presented and compared with other two well-known discrete micro-models. The discrete micro-models discretize masonry micro-structure with nonlinear interfaces for mortar-joints, and continuum elements for units. The proposed continuous micro-model discretizes both units and mortar-joints with continuum elements, making use of a tension/compression damage model, here refined to properly reproduce the nonlinear response under shear and to control the dilatancy. The three investigated models are validated against experimental results. They all prove to be similarly effective, with the proposed model being less time-consuming, due to the efficient format of the damage model. Critical issues for these types of micro-models are analysed carefully, such as the accuracy in predicting the failure load and collapse mechanism, the computational efficiency and the level of approximation given by a 2D plane-stress assumption.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•458 tests on modern mechanically extruded and handmade solid fired clay bricks.•Estimate compressive strength in handmade bricks with hardening response.•Specimens with different cross section’s ...aspect ratio: whole/half brick and cube.•Bearing surfaces: grind, mortar, gypsum, plywood, MDF, gypsum powder and oiled PTFE.•Comparison of international standards assessing strength in solid fired bricks.
This study addresses the evaluation of the confinement effect in the experimental determination of compressive strength in solid fired clay units. The experimental campaign has focused on two different types of solid fired clay bricks, namely mechanically extruded and handmade, with a total amount of 458 specimens. The research considers different standard specimens, such as whole or half brick, and 100 × 100 × 40 mm3 specimen, and nonstandard 40 × 40 × 40 mm3 specimen, subjected to different standard bearing surface treatments, i.e. grinding, capping with cement mortar or gypsum plaster, placing with birch plywood or fibreboard. Additionally, two novel bearing surface treatments are proposed, i.e. covering with gypsum powder, and placing two oiled PTFE leaves. The experimental campaign has focused on four main aspects. First, the evaluation of the compressive strength value in specimens with hardening response. Second, the influence of the cross section’s aspect ratio, defined as the ratio between the specimen’s length and width. Third, the influence of the bearing surface treatment on the determination of the compressive strength. Fourth, the evaluation of the standard compressive strength through the comparison amongst reference standards. The results highlight and quantify the different factors that influence the confinement, while detecting differences depending on the manufacturing process of the unit. In addition, the results reveal the use of oiled PTFE leaves as a promising and fast possibility of low boundary friction to obtain the strength regardless of the specimen shape.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The safeguard of existing masonry buildings requires a meticulous characterisation of the component materials (units and mortar) by using in-situ minimally intrusive techniques. This need is ...especially prominent in the case of heritage buildings in order to minimize their damage and alteration. This paper presents a research on some minor destructive techniques (MDT) for the in-situ evaluation of the mechanical properties of masonry components. In the research, the results derived from MDT were empirically correlated with the compressive strength obtained by using well-known destructive testing (DT) techniques executed in the laboratory. The experimental campaign focused on two different MDT techniques, namely the Pin Penetration Test (PPT) and the Helix screw Pull-out Test (HPT). The PPT is based on the measurement of the depth of penetration of a steel pin. The HPT is based on the measurement of the pull-out load necessary to extract a steel tie inserted into a hole drilled in a brick or in a mortar joint. The experimental campaign also included an evaluation of the Double Punch Test (DPT) by comparison with strength values obtained from mortar specimens prepared and tested following the standard EN 1015–11. The experimental results show a satisfactory agreement between the MDT measurements and the compressive strength obtained with DT. Although both the PPT and HPT are useful for the evaluation of the compressive strength of masonry components, the former exhibits a lower scattering in the experimental measurements.
•541 destructive tests on modern and historical solid clay bricks and mortar joints.•741 minor destructive tests on solid fired clay bricks and mortar joints.•Compressive strength in mortar using Double Punch Test and EN 1015–11 procedure.•Compressive strength evaluation of specimens using the Pin Penetration Technique.•Compressive strength evaluation of specimens using the Helix screw Pull-out Test.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•382 tests on modern mechanically extruded and handmade solid fired clay bricks.•Compressive strength evaluation of specimens stacked and unstacked in height.•Compressive strength evaluation of ...specimens with slenderness between 0.4 and 3.0.•Influence of the manufacturing process on the strength vs. slenderness relationship.
This study evaluates the effect of the specimen’s slenderness and stacking on the experimental measurement of the compressive strength of solid fired clay units. The experimental campaign has focused on two different types of solid fired clay bricks, namely mechanically extruded and handmade, with a total amount of 382 specimens tested. The research considers different standard and non-standard specimens with varying width (40, 50, 60, 70, 80, 90, and 100 mm) and height (40, 80, and 120 mm). The experimental results evidence the influence of the stacking procedure on the compressive strength, with different results depending on the manufacturing process of the unit. The influence of specimen’s slenderness on the compressive strength is more evident and regular in handmade brick specimens than in extruded ones.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•461 experiments on extruded, hydraulic press moulded and handmade solid clay bricks.•Proposal for a small cubic specimen for the measurement of the compressive strength.•Small specimens are tested ...in the three brick dimensions: length, width, thickness.•Anisotropy is quantified in extruded, press moulded, and handmade solid clay bricks.•Probabilistic study of the shape effect and comparison with a standardized specimen.
A study is presented on the use of a non-standard 40 × 40 × 40 mm3 specimen for the experimental measurement of the compressive strength of solid fired clay bricks extracted from existing masonry buildings. The viability of such specimen has been assessed by comparison with experimental results obtained with the standard 100 × 100 × 40 mm3 specimen. The use of the non-standard 40 × 40 × 40 mm3 has two main advantages. First, it significantly reduces the volume of sampled material, which can be severely restrained in architectural heritage buildings. Second, it allows carrying out tests in the three brick dimensions (length, width and thickness), and therefore investigating the anisotropy that clay bricks can exhibit depending of their manufacturing process. The experimental campaign has focused on three different types of solid fired clay bricks, namely mechanically extruded, hydraulic press moulded, and handmade units, with a total amount of 461 specimens. Using the mentioned small cubic specimen, a detailed research on the compressive strength and the anisotropy of different solid clay brick types has been carried out by applying a statistical approach. The experimental results and the statistical processing have shown that the proposed specimen can be utilized for a reliable estimation of the compressive strengths along the three main directions of solid fired clay bricks.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
