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

Study of early age stiffness development in lime-cement blended mortars

Lime-cement blended mortars are frequently used in building conservation, as well as in new masonry constructions. Since mortar plays an important role in governing the non-linear behavior and global performance of masonry from the earliest moments of construction, this work intends to study the evolution of its elastic modulus from very early ages. The development of stiffness in blended mortars has been studied using a recently developed approach called EMM-ARM (Elasticity Modulus Monitoring through Ambient Response Method). The method is based on continuous modal identification of the first flexural resonant frequency of composite beams that contain the material to be tested. The evolution of resonant frequency identified during the experiment can be directly correlated with the Young’s modulus by using the dynamic equation of motion. The experimental program involves validation of the applicability of EMM-ARM in blended mortars by comparison with results from conventional static method of cyclic compression according to EN 12390-13. Three distinct blended mortars (with target workability of 175 mm) with 33%, 50% and 66.67% lime in binder and 1:3 binder aggregate ratio, by volume, have been studied. The evolution of Young’s modulus will permit discussion on interaction of binders involved in the mixes. Such a study will also make it possible to explore the consequences of the observed kinetics of stiffness evolution on the stress development within masonry structures since the early ages of application of the mortar interfaceEuropean Lime Association for funding this project. Funding provided by the Portuguese Foundation for Science and Technology (FCT) to the Research Project PTDC/ECM-EST/1056/2014 (POCI-01-0145-FEDER-016841), as well to the Research Unit ISISE (POCI-01-0145-FEDER-007633)info:eu-repo/semantics/publishedVersio

Experimental investigation on the seismic performance of masonry buildings using shaking table testing

Masonry buildings worldwide exhibited severe damage and collapse in recent strong earthquake events. It is known that their brittle behavior, which is mainly due to the combination of lowtensile strength, largemass and insufficient connection between structural elements, is the main limitation for their structural implementation in residential buildings. A new construction system for masonry buildings using concrete blocks units and trussed reinforcement is presented here and its seismic behavior is validated through shaking table tests. Dynamic tests of two geometrically identical two-story reduced scale (1:2) models have been carried out, considering artificial accelerograms compatible with the elastic response spectrum defined by the Eurocode 8. The first model was reinforced with the new proposed system while the second modelwas built with unreinforced masonry. The experimental analysis encompasses local and global parameters such as cracking patterns, failure mechanisms, and in-plane and out-of-plane behavior in terms of displacements and lateral drifts from where the global dynamic behavior of the two buildings is analyzed comparatively. Finally, behavior factors for the design recommendations in case of unreinforced masonry are alsoevaluated.QREN (POFC) - ADI - Agência de Inovaçã