Browsing by Author "Eng, Warren"

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    Finite element modelling of masonry diaphragm walls subjected to lateral and thermal loadings
    (1989) Eng, Warren; Shrive, Nigel G.
    The use of masonry dates back centuries, yet only recently has research been con­ducted into the efficient application of this material to structures. A new form of construction which has achieved popularity in the United Kingdom is the masonry diaphragm wall. The typical diaphragm wall consists of two wythes of masonry connected at regular intervals by solid masonry webs to form box or I-sections; this form of construction is significantly stiffer than traditional forms of masonry such as the cavity wall. A properly designed diaphragm wall will fulfill many of the requirements of a b'uilding envelope and is therefore a much more efficient use of masonry. The work presented in this thesis addresses two maJor concerns with respect to the practical application of masonry diaphragm walls in Canada: the lack of adequate methods of analysis, and the performance of diaphragm walls subjected to high levels of differential thermal loading. The finite element method was the primary method of analysis utilized as ex­tensive laboratory testing would be expensive and time-consuming. The validity of using the finite element method to model masonry diaphragm walls was verified in two phases. The first involved the modelling of a previous British test of a plain blockwork diaphragm wall. The density of the materials was found to be an important modelling parameter in free standing walls. For the second phase of the model verification, four plain masonry walls were constructed from local materials: three diaphragm walls and one cavity wall. These walls were subjected to lateral loading. The flexural tensile stresses from the finite element modelling compared favourably with the corresponding results from a sim­plified engineering analysis. The increased lateral load capacity of the diaphragm wall form was also confirmed. The thermal stress analysis of masonry walls subjected to large steady stat.e temperature differentials was then conducted. The finite element modelling proce­dure was used. The resulting principal tensile stresses in the uncompressed, plain diaphragm walls were found to be excessive, ranging from 2 to 3 MPa. The lo­cation of the maximum principal tensile stresses was in the region of the interior web-flange interface at the top of a wall. It is unlikely that masonry diaphragm walls will survive in the harsh Canadian climate without a reduction in these maxi- mum stresses. Prestressing of diaphragm walls may be required before they become viable in Canada.