Applications of Cement-Based Smart Composites to Civil Structural Health Monitoring: A Review

In recent years, cement-based smart composites (CSCs) doped with conductive filler have attracted increasing research interest because of their high potentiality as self-sensing materials for civil Structural Health Monitoring (SHM) applications. Nevertheless, several issues are still open and need further studies. This paper presents an extensive state-of-the-art in which investigations on CSCs are summarized and critically revised, with the primary aim of outlining the main limits and development points. The literature review first addresses in detail several specific issues related to fabrication and operation as sensing elements of CSC samples. State-of-the-art applications of CSCs to SHM of reduced-, medium- and full-scale structural prototypes are extensively reviewed afterwards, resulting in a database useful to critically revise the main trends and open issues of the research in this field

Computer-aided decision making for regional seismic risk mitigation accounting for limited economic resources

Seismic risk mitigation levels for an existing building are a balance between the reduction of risk and the cost of rehabilitation. Evidently, the more that is paid the more risk is reduced; however, due to limited public budgets a practical approach is needed to manage the risk reduction program when a portfolio of buildings is concerned. Basically, decision makers face a challenge when there are a large number of vulnerable buildings and there is no plan for how to allocate the appointed budget. This study develops a technological platform that implements a decision-making procedure to establish how to optimally distribute the budget in order to achieve the maximum possible portfolio risk reduction. Decisions are made based on various presumed intervention strategies dependent on building’s level of risk. The technological platform provides an interactive, user-friendly tool, available online, that supports stakeholders and decision makers in understanding what the best economic resource allocation will be after selecting the available budget for a specific portfolio of buildings. In addition, the ease of use enables the user to analyze the extent of risk reduction achievable for different budget levels. Therefore, the web platform represents a powerful tool to accomplish two challenging tasks, namely optimal budget selection and optimal budget allocation to gain territorial seismic risk mitigation

Earthquake induced floor accelerations on a high-rise building: Scale model tests on a shaking table

The paper discusses results of shaking table tests on an in-scale high-rise building model. The purpose was to calibrate a dynamic numerical model for multi-hazard analyses to investigate the effects of floor acceleration. Accelerations, because of vibration of non-structural elements, affect both the comfort and safety of people. The research investigates the acceleration effects of both seismic and wind forces on an aeroelastic in-scale model of a multi-story building. The paper discusses the first phase of experiments and gives results of floor accelerations induced by several different base seismic impulses. Structural analyses were first performed on the full-scale prototype to take soil-structure interaction into account. Subsequently the scale model was designed through aeroelastic scale laws. Shaking table experiments were then carried out under different base accelerations. The response of the model and, in particular, amplification of effects from base to top are discussed

Experimental behavior of existing RC columns strengthened with HPFRC jacket under concentric and eccentric compressive load

Reinforced concrete (RC) structures built before the 1970 represent a large portion of the existing European buildings stock. Their obsolescence in terms of design criteria, materials, and functionality is becoming a critical issue for guaranteeing adequate compliance with current structural codes. Recently, a new jacketing system based on the use of high-performance fiber-reinforced concrete (HPFRC) has been introduced for strengthening existing RC building members. Despite the promising aspects of the HPFRC jacketing technique, currently, a comprehensive and systematic technical framework for its implementation is still missing. In this paper, the experimental performance of RC columns strengthened with the HPFRC jacket subjected to pure axial load and combined axial load-bending moment uncoupled from shear is investigated. The test outcomes confirmed a significant improvement of the structural performance for the strengthened columns, especially for higher values of eccentricity. Finally, a standard-based practice-oriented analytical tool for designing retrofit interventions using the HPFRC jacket is proposed. The comparison between the calculated and experimental results revealed a satisfactory prediction capability

Experimental results of a national technical assessment procedure on commercial FRP for structural strengthening: wet-lay-up systems

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Experimental in-plane lateral response of a full-scale adobe masonry wall with opening

A large amount of world population lives nowadays in earthen buildings, often constructed only based on construction practice and within earthquake-prone regions. In the recent history, several strong earthquakes had dramatic consequences on these structures, highlighting their significant seismic vulnerability due to multiple reasons, such as poor mechanical properties, poor detailing, and large inertia mass. Several aspects of seismic performance of existing earthen constructions need to be investigated through full-scale experimental testing. In this regard, the present study aims at contributing to the investigation by testing a full-scale adobe masonry wall with a central door-type opening under in-plane lateral loading with cyclic fashion. The mechanical behaviour of materials, specimen's design, loading protocol and instrumentation setup are described. The experimental response curves, observed damage evolution and failure mode are discussed, especially focusing on dissipation capacity of the wall

Experimental characterization of tensile strength of steel and fibre rovings also under environmental conditioning

The efficiency of the strengthening techniques by externally applied materials can be improved enhancing the debonding strength of the reinforcement from the support by the use of connectors (anchor spikes) consisting of unidirectional bundles of fibres embedded in concrete or masonry by means of organic or inorganic matrices. The use of connectors is suggested in various codes and guidelines of strengthening techniques by composite materials and provisions for their application are given, but currently there are no details for the qualification of the material. In order to investigate anchor spikes made of glass, basalt, aramid, carbon, PBO and steel, a large experimental campaign was carried out at the Materials and Structures Laboratory of the University of Sannio. The tests allowed to evaluate the mechanical characteristics (tensile strength, modulus of elasticity, deformation at the maximum load) of the anchor spikes constituted by only dry fibres, not impregnated, also as a result of environmental conditioning such as freezing and thawing, controlled humidity, alkaline and saline environment

Experimental study on the in-plane response of adobe masonry wallets strengthened with textile reinforced matrix systems

Seismic strengthening of existing adobe masonry (AM) buildings has been recognized as a critical issue due to the dramatic consequences of recent seismic events occurred especially in developing countries, where a great part of the population lives in those constructions. Previous studies investigated the effectiveness of different retrofitting techniques by means of experimental programs consisting of either dynamic or static tests on reduced- or full-scale specimens, representing partial or complete AM dwellings. In this study, the output of diagonal compression tests on adobe masonry panels before and after external strengthening are presented. Three series of specimens were tested, namely, unreinforced and strengthened wallets with textile reinforced matrix (TRM) systems made of either hemp or glass meshes. Those tests benefitted from the characterization of the mud mortar that was used for both masonry joints and matrix, representing typical characteristics of existing Italian AM buildings. Main testing outcomes obtained for the AM wallets, particularly in terms of observed damage and response curves, are presented and discussed. In the end, the effectiveness of the applied TRM systems in the improvement of shear strength and ductility capacity is assessed