Numerical analysis of concrete block masonry beams under three point bending

A parametrical study of masonry beams through numerical modelling has been performed in order to better understand the mechanical behaviour of these elements. Boundary conditions, geometry and reinforcement ratios are the main parameters analysed in this study. The numerical simulation is performed with DIANA® software, based on the Finite Elements Method. A comparison between numerical and experimental results is presented in order to validate the simulation. In conclusion, it was verified that the behaviour of masonry beams is greatly affected by the boundary conditions and geometry, as expected. With regard to reinforcement, it was noted that horizontal reinforcement increases the flexural strength of beams. On the other hand, variation in horizontal reinforcement had no influence on the shear resistance of masonry beams. Finally, the combination of horizontal and vertical reinforcement is shown to enhance the flexural and shear behaviour of masonry beams.This work was in part supported by a contract from DISWall - "Development of innovative systems for reinforced masonry walls' - (COOP-CT-2005-018120) awarded by the European Commission. The first author was supported by the Programme Alssan, the European Union Programme of High Level Scholarships for Latin America, Scholarship no E06D100148BR

Assessment of compressive behavior of concrete masonry prisms partially filled by general mortar

The usage of general mortar for embedding and partially filling of units in 12 masonry prisms is evaluated through compressive tests. Filled and unfilled prisms were 13 tested in order to verify the differences on their compressive behavior. Four mortar 14 mixes with three water/cement ratios for each mix were used in tests. Results indicated 15 small differences between filled and unfilled masonry prisms. Mortar had a small 16 influence in the compressive strength of the masonry. However, a more significant 17 influence could be observed on secant elastic modulus, compressive fracture energy and 18 deformations of masonry prisms. Besides, an analytical model to represent the stress vs. 19 strain diagram of masonry prisms is proposed. The analytical model depends on the 20 compressive strength of mortar and masonry prism. Furthermore, results indicated that 21 the usage of general mortar for embedding and filling masonry prisms can be a solution 22 in terms of building technology.This work was partly supported by the European Commission's DISWALL contract (Development of innovative systems for reinforced masonry walls - COOP-CT-2005-018120). The first author was supported by the Alssan Programme, the European Union Programme of High Level Scholarships for Latin America, Number E06D100148BR

Improved construction of concrete viaducts with movable scaffolding systems in Spain

The current paper relates the state of the art of construction of viaducts with a movable scaffolding system (MSS). Two different procedures are introduced: the traditional sequence and the new sequence applied to some viaducts in Spain. The traditional sequence consists of two phases: first, concreting the bottom slab and webs, and then concreting the top slab of the deck. Once the first and second casting phases are completed, the total prestressing force is introduced. The new sequence consists of concreting a self-supporting core (i.e., the bottom slab, webs, and only a portion of the top slab). Once the self-supporting core has hardened, a partial prestressing force is introduced so that the scaffolding can be advanced to the next span; the central zone of the top slab is cast in a second phase. Both sequences are described here with their constructive peculiarities and issues.Peer ReviewedPostprint (author's final draft

Experimental analysis of reinforced concrete block masonry beams using pre-fabricated planar trussed bars

Masonry spandrels together with shear walls are structural components of a masonry building subjected to lateral loads. Shear walls are the main components of this structural system, even if masonry spandrels are the elements that ensure the connection of shear wall panels and the distribution of stresses through the masonry piers. The use of prefabricated truss type bars in the transversal and longitudinal directions is usually considered a challenge, even if the simplicity of the applications suggested here alleviate some of the possible difficulties. This paper focus on the experimental behavior of masonry spandrels reinforced with prefabricated trusses, considering different possibilities for the arrangement of reinforcement and blocks. Reinforced spandrels with three and two hollow cell concrete blocks and with different reinforcement ratios have been built and tested using a four and three point loading test configuration. Horizontal bed joint reinforcement increased the capacity of deformation as well as the ultimate load, leading to ductile responses. Vertical reinforcement increased the shear strength of the masonry spandrels and its distribution play a central role on the shear behavior.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 Al(ss)an, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. E06D100148BR

Influence of aggregates grading and water/cement ratio in workability and hardened properties of mortars

Mortar is the material responsible for distribution of stresses in masonry structures. Knowledge about the fresh and hardened properties of mortar is fundamental to ensure a good performance of masonry walls. Water/cement ratio and aggregates grading are among several variables that influence physical and mechanical behaviour of mortars. An experimental program is presented in order to evaluate the influence of aggregates grading and water/cement ratio in workability and hardened properties of mortars. Eighteen compositions of mortar are prepared using three relations cement:lime:sand, two types of sand and three water/cement ratios. Specimens are analyzed through flow table test, compressive and flexural strength tests. Results indicate that the increase of water/cement ratio reduces the values of hardened properties and increases the workability. Besides, sands grading has no influence in compressive strength. On the other hand, significant differences in deformation capacity of mortars were verified with the variation of the type of sand. Finally, some correlations are presented among hardened properties and the compressive strength.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 Al beta an, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. E06D100148BR

Parametrical study of masonry walls subjected to in-plane loading through numerical modeling

This paper deals with the numerical assessment of the influence of parameters such as pre-compression level, aspect ratio, vertical and horizontal reinforcement ratios and boundary conditions on the lateral strength of masonry walls under in-plane loading. The numerical study is performed through the software DIANA® based on the Finite Element Method. The validation of the numerical model is carried out from a database of available experimental results on masonry walls tested under cyclic lateral loading. Numerical results revealed that boundary conditions play a central role on the lateral behavior of masonry walls under in-plane loading and determine the influence of level of pre-compression as well as the reinforcement ratio on the wall strength. The lateral capacity of walls decreases with the increase of aspect ratio and with the decrease of pre-compression. Vertical steel bars appear to have almost no influence in the shear strength of masonry walls and horizontal reinforcement only increases the lateral strength of masonry walls if the shear response of the walls is determinant for failure, which is directly related to the boundary conditions.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 Alssan, the European Union Programme of High Level Scholarships for Latin America, Scholarship No. E06D100148BR

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

Composition study of a mortar appropriate for masonry cavities and joints

It is well known that unreinforced masonry behaves as a quasi-brittle material when subjected to seismic loading. The construction in unreinforced masonry is usually not allowed in regions with moderate to high seismic hazard. The alternative to unreinforced masonry and even to reinforced concrete and steel construction is reinforced masonry, which appears to perform adequately under seismic loading. This work deals with the challenging issue of contributing to the definition of a fast and simples construction system using reinforced masonry, by replacing the grout by a general purpose bed mortar, capable of being used also to fill vertical cells with vertical reinforcement. The major difficulty is to find a mortar that is also suitable to fill vertical hollow cells of concrete units. This work presents preliminary results from the study of different mortars, corresponding to different compositions, in order to find appropriate workability and sufficient fluidity. The analysis is based on a comparative study including the characterization of the fresh mortar properties, such as workability, and the hardened properties, such as modulus of elasticity, flexural strength and compressive strength. The assessment of the mortar adequacy to fill the hollow cells is also analyzed by the execution of masonry prisms, followed by a qualitative analysis of the fill

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

Alvenaria armada : soluções inovadoras em Portugal

Neste trabalho pretende-se abordar aspectos relacionados com as tipologias de paredes de alvenaria estrutural e com a concepção de edifícios em alvenaria. Além disso, são apresentadas duas principais soluções em alvenaria armada que têm vindo a ser objecto de estudo na Universidade do Minho. Discutem-se aspectos de concepção e tipologias e complementarmente os resultados experimentais obtidos na validação experimental de ambas as soluções