Stone arch bridges make a comeback

Bridge Design and Engineering: Stone arch bridges make a comeback Planning permission has been granted for the construction of what is believed to be Europe’s first multi-span stone arch bridge in around 100 years

A review on acoustic emission monitoring for damage detection in masonry structures

Acoustic emission monitoring is widely used for damage detection in materials research and for site monitoring. Its use for masonry structures is however challenging due to the highly heterogenic nature of masonry and rapid signal attenuation. However, the non-invasive nature and high sensitivity of the technique also provide interesting opportunities, especially for historical masonry structures, to locate damage, identify severity of damage and rate of deterioration. Aim of this paper is to provide an extensive literature review on the application of the acoustic emission technique for masonry structures, addressing specific challenges and recent findings. AE-based methods for damage assessment in masonry are discussed in view of monitoring approaches, wave propagation, source location and crack development under static, fatigue and creep loading. Site applications are discussed for identifying crack location and crack propagation in historical masonry towers, buildings and masonry arch bridges. The paper concludes with future challenges identified in this research field

Strain evolution of brick masonry under cyclic compressive loading

Long-term fatigue tests in compression were performed on low-strength brick masonry prisms under laboratory conditions at different maximum stress levels. The maximum and minimum total longitudinal deformations with the loading cycles were recorded. The experimental results revealed that fatigue life is divided into three distinct stages. The recordings were further analysed to develop an analytical expression for the prediction of the development of strain during the fatigue life of masonry. A set of three mathematical equations were proposed to predict the three characteristic stages of fatigue. The developed expressions, related the normalised total longitudinal strain with the normalised maximum applied stress. The proposed model provides good agreement with the mean available data at any maximum stress level and could be used to to evaluate the remaining service life, plan maintenance works minimising life-cycle costs and prevent premature failures Continuity of the curves at the intersection points in terms of slope and numerical values ensures accuracy of the method and results to a differentiable function

Influence of environmental degradation on dynamic properties of masonry bridges

Brick and Block Masonry - Trends, Innovations and Challenges contains the lectures and regular papers presented at the 16th International Brick and Block Masonry Conference (Padova, Italy, 26-30 June 2016). In an ever-changing world, in which innovations are rapidly implemented but soon surpassed, the challenge for masonry, the oldest and most traditional building material, is that it can address the increasingly pressing requirements of quality of living, safety, and sustainability. This abstracts volume and full paper USB device, focusing on challenges, innovations, trends and ideas related to masonry, in both research and building practice, will proof to be a valuable source of information for researchers and practitioners, masonry industries and building management authorities, construction professionals and educators.© 2016 Taylor & Francis Group, London. The paper presents some preliminary analyses devoted to the identification of suitable models able to provide the frequency decay of a damaged masonry structure on the basis of the observed damage pattern. In particular the analysis will be carried out with reference to some comparison FE models, and by introducing two distinct damage patterns, i.e. an elastic modulus decay of an external layer of the bridge arch, or a localised reduction of section due to impact or brick and stone detachments. The worked out examples allow checking of a very simple formulation based on the frequency evaluation through the static displacement equivalence of energy, and the splitting of the curvature diagram in the average part plus an added impulse term due to the presence of defects. The proposed formula is in good agreement with the FE analyses and sufficiently simple to be used for the detection of the damaged material properties, as a function of the average frequency decay

Sustainability of bridge maintenance

Bridge maintenance activities are important to consider within sustainable development due to the cost and environmental impact associated with various maintenance activities. Comparisons have been made between different bridge structural forms, based on materials, components and construction method, but less information is available on bridge maintenance activities to help decide a sustainable structural form. Typical maintenance aspects of the predominant forms of bridge structure (i.e. concrete, steel and masonry bridges) were considered in this study to reveal their sustainability in terms of materials, energy, transportation, human health and ecosystems. The results indicate that concrete and steel bridge maintenance activities have an average impact of 42% and 46% compared with 12% for masonry bridge maintenance activities. It is concluded that the component parts of concrete and steel bridges should be revised as they play an integral role in the selection of maintenance options

Laboratory and field studies on the use of acoustic emission for masonry bridges

Acoustic emission (AE) monitoring has the unique ability to record crack propagation and the response of structures to live loading; however, its use for masonry is currently very limited. AE technique was applied to a series of small-scale laboratory specimens under compression and shear to develop deeper understanding of the stages of fracture development process and signal characteristics under quasi-static and long-term fatigue loading. Field monitoring was subsequently carried out on a brick masonry arch bridge to identify its response to traffic loading, structural condition and efficacy of strengthening works with the help of laboratory test results

Damage detection of bridges through acceleration monitoring

The damage early warning of bridges is a mandatory issue if we want to guarantee the safety of transport lines."br" In principle, bridges should show a non-linear damaged phase which has enough remaining capacity to avoid"br" brittle collapse, while permitting the identification of the decrease in stiffness, and therefore the warning about"br" the efficiency of the structure (Farrar & Warden 2006)."br" It is however to point out that the change detection of the bridge dynamic properties is a very complicated task,"br" due to the variable environmental and loading conditions, and the small entity of change that by far severe"br" damages produce (Magalhães et Al., .2012)."br" In the paper the preliminary results of a two year long European project, granted by the Infravation Call, are"br" presented. In this period, a consistent number of bridges all around the world have been monitored, and some"br" specimen bridges thoroughly investigated in laboratory (see for instance the project description at the site"br" http://www.infravation.net/projects/SHAPE)."br" The performed investigation has shown that the continuous monitoring of bridges can be transformed in a sort of"br" bridge behaviour intrinsic model which fixes the range of normal operation of the bridge itself. By this way,"br" outliers can be identified, but a very important issue is the evaluation of the extent of the change that can start the"br" warning activity."br" Among the possible strategies, it is shown that algorithms that evaluate the derivative of the change can be"br" effective in pointing out the onset of a permanent damage (Nikowski & Jain, 2009)

Critical review of research on high-cycle fatigue behaviour of brick masonry

Prediction of the level of service load above which accumulative damage occurs is a key priority for the masonry arch bridge owners. Limited investigations have been undertaken previously on the high-cycle fatigue behaviour of brick masonry in order to establish the link between the fatigue phenomenon in brick masonry and the serviceability limit state for masonry arch bridges. But to date there are still many uncertainties of the research published regarding predicting the fatigue performance. This paper provides a critical review on the high-cycle fatigue behaviour of brick masonry. Current state of the knowledge and areas requiring further research are also presented

Fatigue deterioration process of brick masonry

In order to develop greater understanding of the long-term fatigue deterioration process of masonry structures, e.g. bridges, the effects of quasi-static and high-cycle fatigue loading have been studied through a series of small-scale laboratory test samples. With the help of acoustic emission monitoring, stages of the damage accumulation processes have been investigated under compression and shear for brick masonry. The relationship between stress level and fatigue life was characterised through S-N type curves and mathematical models. The concept of fatigue and permissibility limit were discussed and related to practical application. Methodology for assessing the life expectancy of masonry structures was demonstrated for masonry arch bridges with potential for wider application