Abstract
The external envelope walls of a significant percentage of the residential building stock in Southern European countries is commonly constituted by infill masonry walls. However, thousands of square meters of this masonry wall typology presents severe issues of cracking and instability, related to the incorrect and deficient support conditions of the outer brick panel of the double-leaf wall solution. In this work, an experimental campaign divided in two phases has been performed to evaluate the effectiveness of two different remedial wall ties retrofitting techniques (Solution A and Solution B) used for double leaf horizontally hollowed clay brick masonry façades. The first phase of the experimental campaign was performed on 120 isolated specimens of horizontally hollowed clay bricks, resorting to post- and pre-NP EN 771-1 brick exemplars (that is, new and pre-existent aged bricks, respectively), as well as on 4 square wallettes, with a side length of 1.20 m, considered as representative of a real scale scenario, for evaluating the two remedial wall ties retrofitting techniques. The second phase of the experimental campaign was performed to fully characterize the different failure types as well as the slipping phenomena observed in the first phase of the experimental campaign, focusing solely on the retrofitting technique Solution B and comprises 24 tests performed on isolated specimens, resourcing to new and pre-existent aged bricks as well. The results obtained by the use of these techniques revealed an average anchorage strength value ranging from 0.25 to 2.5 kN for each tested tie-bar. Solution B reveals an increase of double of the anchorage strength value in comparison to Solution A. In this sense, the global results revealed a suitable applicability of both retrofit studied solutions.
Highlights
As a consequence of population and economic growth, an increasing demand for indoor thermal comfort and energy efficiency requirements has arisen, implying new challenges related to buildings’ thermal performance in the European built environment [1]
Solution A is a based on the insertion of a remedial helicoidal tie that is inserted through percussion and connects the two wall leafs solely by friction
This paper focused on the effectiveness of two different remedial wall ties retrofitting techniques with the purpose of tackling a recurrent problem concerning the instability of double-leaf masonry enclosure walls
Summary
As a consequence of population and economic growth, an increasing demand for indoor thermal comfort and energy efficiency requirements has arisen, implying new challenges related to buildings’ thermal performance in the European built environment [1]. Concerning the critical role of buildings’ external envelope walls in terms of protection from the environmental elements whilst assuring desirable indoor thermal comfort conditions to the building occupants, one of the most debatable measures in terms of constructive systems solutions has been the external thermal bridge correction by means of clay brick slips or veneer cladding, aligned with the underlying strategy of the European Union (EU) energy policy framework for reducing the environmental impacts and the ecological footprint, as well as to reduce energy consumption through improving energy efficiency in buildings without compromising the living quality standards [8,9] Despite these constructive systems solutions contributing to the improvement of the buildings’ façade thermal behavior, insufficient testing and technological validation has been responsible for a considerable amount of pathologies associated with deficient support conditions, and severe cracking and instability of horizontally hollowed clay brick enclosure infill masonry walls have been observed. The results acquired for both retrofitting techniques are thoroughly presented and discussed
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