Study of the behaviour of reinforced masonry wallets subjected to diagonal compression through numerical modelling

Shear walls are subjected to flexure and shear efforts in conjunction with compressive stresses associated to the gravity loads. In shear mode, diagonal cracks develop at the unit-mortar interface or both at the unit-mortar interface and through units as result of a biaxial tension-compression stress state, which in unreinforced masonry generally mean the collapse. The brittle failures of unreinforced masonry shear walls, which are more remarkable with high axial loads, may be prevented by the use of steel reinforcement. Diagonal compression tests allow obtaining a good prediction of the tensile strength of masonry walls in this biaxial tension-compression stress state. This paper aims to study the behaviour of reinforced masonry in diagonal compression tests through numerical modelling. A series of diagonal compression tests carried out on concrete block masonry with distinct types of reinforcement’s arrangements are modelled using the software DIANA®. Results indicate that horizontal and vertical reinforcements applied in conjunct provide an increase on the shear strength and ductility. On the other hand, the application of horizontal reinforcements alone leads only to an increase of ductility

Assessment of the flexural behavior of concrete block masonry beams

This paper focus on the experimental flexural behavior of masonry beams. In the sequence of the development of a novel structural solution for reinforced masonry walls at University of Minho, different possibilities for the construction of lintels with concrete block masonry have been tested. Reinforced concrete beams with three and two hollow cell concrete blocks and with different reinforcement ratios have been built and tested in a four point loading test configuration. It was clear that horizontal bed joint reinforcement increased the ultimate flexure capacity as well as the ultimate deflection, leading to much more ductile responses. Moreover, it was also clear that a more deep analysis should be made regarding the role of the compressive strength of masonry in the parallel direction to the bed joints on the global behavior of the masonry beams.This work was partly supported by contract DISWALL – “Development of innovative systems for reinforced masonry walls” – COOP-CT-2005-018120 from the European Commission. The first author was supported by the Programme AlBan, the European Union Programme of High Level Scholarships for Latin America, Scholarship nº E06D100148BR

Influence of the geometry of units and of the filling of vertical joints in the compressive and tensile strength of masonry

Attention is given to the mechanical properties of concrete block masonry, with respect to its compressive and tensile strength. These properties are important parameters in the in-plane lateral behaviour of masonry walls, determining their resistance and ductility. Such properties play also a central role when analytical and numerical analysis is used for simulating or predicting the behaviour of masonry structures. The influence of two selected parameters on the mechanical properties of masonry is discussed, namely the geometry of the units and the filling of the vertical joints. Results show that masonry under compression behaves as a homogeneous material and the stress-strain diagrams can be represented by a parabola similarly to what is suggested for structural concrete. in case of tensile strength, filling of vertical joints appears to influence considerably the tensile strength. The filling of the vertical joints increased the strength but lead to a more brittle behaviour.The first author was supported by the Programme Alβan, the European Union Programme of High Level Scholarships for Latin America, Scholarship nº E06D100148BR

Masonry components

Masonry is a non-homogeneous material, composed of units and mortar, which can be of different types, with distinct mechanical properties. The design of both masonry units and mortar is based on the role of the walls in the building. Load-bearing walls relate to structural elements that bear mainly vertical loads, but can serve also to resist to horizontal loads. When a structural masonry building is submitted to in-plane and out-of-plane loadings induced by an earthquake for example, the masonry walls are the structural elements that ensure the global stability of the building. This means that the walls should have adequate mechanical properties that enable them to resist to different combinations of compressive, shear and tensile stresses.The boundary conditions influence the resisting mechanisms of the structural walls under in-plane loading and in a buildings the connection at the intersection walls are of paramount importance for the out-of-plane resisting mechanism. However, it is well established that the masonry mechanical properties are also relevant for the global mechanical performance of the structural masonry walls. Masonry units for load-bearing walls are usually laid so that their perforations are vertically oriented, whereas for partition walls, brick units with horizontal perforation are mostly adopted

Evidence of vertical transmission of Senecavirus A in naturally infected sows.

Abstract: Senecavirus A (SVA) is a Picornaviridae RNA virus that causes vesicular disease (VD) and transitory neonatal losses in pigs. The major ways SVA is spread are by oral, nasal, and feces. Vertical transmission of SVA was investigated during a VD epidemic in a farrow-to-finish herd in Brazil. Vesicular lesions were observed on sows before farrowing and on piglets within 24 h of birth. Analyses included RT-qPCR, viral isolation, sequencing, and virus-neutralization assays on serum, vesicular fluid, colostrum, and milk. Five out of ten sows were viremic before farrowing, and 46.7% of tested piglets had high viral loads in the first 24 h after birth. Infectious virus was detected in colostrum and milk from one postnatal sow. Despite high levels of neutralizing antibodies (nAbs) in piglet serum, colostrum, and milk, piglets were not protected from viremia and clinical illness. These findings support the vertical and congenital transmission of SVA

Developing innovative systems for reinforced masonry walls

The Commission of the European Communities has recently funded a CRAFT research project aimed at developing innovative systems for load and non-load-bearing reinforced masonry walls. The project involves twelve partners coming from four different European countries, among which there are universities and research centres, small and medium enterprises for the production of clay and concrete units and mortars, a company for advanced metal products and industrial associations of brick and block producers. The development of the reinforced masonry walls is based on the advancement of vertical reinforcement and fastenings, of mortar and concrete and on their integration with special clay and concrete blocks for the definition of new construction systems. The foreseen advantages are: new possibilities for masonry; more economical construction; quality increase for masonry walls; crack-free and earthquake resistant construction. The project follows three steps: assessment of the technical and economical feasibility of the envisaged construction technologies by means of extensive experimental and numerical activities; construction of prototypes as demonstration of the proposed technologies and materials; in situ testing to completely validate the systems. In the present contribution, an overview of the main objectives and steps of the project is given. Furthermore, the different construction systems that are being developed and designed are described. The main fields of application and the main technical problems encountered for the different construction systems is described, together with the experimental program outlined in order to characterize their mechanical behaviour under different serviceability and ultimate conditions