Effects of support conditions on lintel-masonry interaction

This paper describes research into the behaviour of so-called "composite lintels" i.e. load bearing masonry in combination with prefabricated concrete lintels. Eighteen identical walls were loaded in plane to rupture. Nine layers of stretcher bond masonry, 562.5 mm in height, were built on prefab concrete lintels (60×100 mm2) with a span of 2800 mm. The effects of two types of supports and two types of loading on the mechanical behaviour of in plane loaded composite lintels were studied. Roller supports were simulated by suspending steel blocks from the roof beam of the test frame. A support condition, often used in practice, was simulated by a layer of felt on a brick. Two series of six walls were symmetrically loaded at four points. A third series of six walls were asymmetrically loaded at one point. The mean failure shear load for the four point loading condition was Vfail = 31 kN. For the one point condition it was Vfail = 24.4 kN. On average, the ultimate load (Fult) was 15% higher than the failure load (Ffail). Supported on rollers, three walls failed in the constant moment area (mid span). The fifteen other walls failed in the maximum shear load area near the supports. The height of the compression zone at mid span depended on the support condition and was largest for the felt support condition, where horizontal movement of the lintel was restrained. The support condition (rollers or felt) had a negigible effect on the load bearing capacity

Introduction to post-tensioned shear walls of calcium silicate element masonry

In Western Europe, load-bearing masonry structures are frequently built with calcium silicate elements (CASIELs) combined with thin layer mortar. The height of CASIEL masonry shear walls is limited by the overturning moment. The recent development of high strength CASIELs opens new perspectives. By prestressing masonry, the moment and shear capacity of shear walls can be increased, providing overall stability of higher buildings. Unfortunately, application of this construction method in building practice is limited due to lack of design rules for prestressed masonry in European standards, e. g. Eurocode 6 [1]. Additionally, experimental data on prestress losses due to creep and shrinkage of high strength CASIEL masonry are not yet available. At Eindhoven University of Technology, a project has been set up to systematically investigate the moment and shear capacity of post-tensioned shear walls of CASIEL masonry by means of experimental, numerical and analytical research. Final goals of the project are the development of design rules for post-tensioned (CASIEL) masonry and guidelines for simple and effective post-tensioning systems which ensure overall stability of buildings during construction and working life