Dr. Eng. Ahmed Elyamani

This paper summarizes recent investigations into the structural and material response of ambient-dry and wet clay-brick and lime-mortar masonry elements, with focus on those used in heritage structures in Historic Cairo. In addition to cyclic tests on large-scale masonry walls subjected to lateral displacement and compressive gravity loads, the studies included complementary tests on small scale masonry panels and material specimens. It is shown that moisture can have a notable effect on the main material properties, including the shear and compression strengths, brick-mortar interaction parameters, and the elastic and shear moduli. The extent of the moisture effects is a function of the governing behaviour and material characteristics as well as the interaction between shear and precompression stresses and can lead to a loss of more than a third of the stiffness and strength in addition to a reduction in ductility. Simple and cost-effective strengthening techniques, using textile-reinforced mortars, for enhancing the lateral performance of low-strength heritage masonry element, are also considered in this study. The effectiveness of the strengthening approach is illustrated and quantified through additional tests on the small-scale panels and large-scale wall specimens. It is shown that simple analytical assessment methods can be reliably adapted for predicting the response of the wall specimens, in terms of the lateral stiffness, strength and overall load-deformation behaviour.

This work intends to provide seismic vulnerability analysis for a building stock in Al Khalifa District, Fatimid Cairo while focusing on the historic buildings in the area. The work represents part of an interdisciplinary study targeting the management and conservation of a UNESCO World Heritage Site. The project inspects several aspects including behavior of masonry walls, structural health monitoring of selected structures, conservation studies, in addition to influence of rising ground water. In the current study, seismicity of Egypt generally and Cairo specifically is reviewed. Afterwards, large-scale seismic vulnerability is adopted to calculate the vulnerability index for buildings within the study area. Data are collected through extensive on-site surveys for more than one hundred buildings. Observed typologies are listed alongside possible mechanisms of failure. Egypt has moderate seismic hazard; however, many buildings are prone to damage due to inadequate seismic design. This leads to retrofitting requirements to reduce seismic vulnerability and adhere to imposed seismic requirements in design codes. The study is intended to understand seismic risk of buildings within study area as part of a comprehensive study. Developed vulnerability map show that many buildings are prone to damage during seismic events.

This paper examines the experimental structural response of clay brick lime mortar masonry walls in wet and ambient-dry conditions. The properties of fired-clay bricks and hydraulic lime-mortar materials are selected to resemble those of existing heritage masonry structures in Historic Cairo. The investigation includes tests on square panels under diagonal compression, and large-scale walls subjected to gravity loading and in-plane lateral cyclic displacements. In addition to the conditioning type, the effectiveness of strengthening with helical bars in horizontal bed joints is also investigated. Implications of embedding helical bars in lime mortar as well as the provision of end anchorages are assessed. The complete load-deformation response of the large-scale members is also evaluated, including the main behavioural characteristics and failure modes. The results show that moisture has a notable effect on the main mechanical properties and overall structural response of such masonry components. For the panels subjected to diagonal compression, the strength reduction under wet conditions is shown to be more than 40% compared to the dry counterparts. For the large-scale walls, subjected to combined lateral loading and precompression, this reduction is significantly lower but can exceed 10%. It is also shown that the provision of helical bars can, depending on their end anchorage and arrangement, double the diagonal tension strength of masonry and offset the adverse effects occurring due to moisture.

The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island.