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Seismic Plus EneRgy Upgrading of Masonry Buildings using Advanced Materials

Periodic Reporting for period 1 - SPEctRUM (Seismic Plus EneRgy Upgrading of Masonry Buildings using Advanced Materials)

Período documentado: 2018-12-01 hasta 2020-11-30

This project has been inspired by the always more demanding need to upgrade the existing unreinforced masonry (URM) buildings due to their poor seismic performance resulting in severe human and economic losses and their low energy performance which significantly increases their energy consumption. These traditional structures are far from the levels of the current standards for seismic capacity and energy consumption and suffer from deterioration due to ageing of materials, environmental degradation, experience of several earthquakes and lack of maintenance. Therefore, this project tried to confront both seismic and energy deficiencies simultaneously for the most common traditional URM building typologies in the context of current EU regulations for building energy savings and protection of cultural heritage.
This combined retrofitting can be realised by integrating advanced strengthening and insulating materials (Fig. 1), and provides several benefits to society and the environment:
(i) Safer structures secure a higher protection of human lives and the built cultural heritage.
(ii) Higher energy efficiency reduces dramatically gas emissions and thus, protects the environment.
(iii) A concurrent retrofitting achieves cost efficiency reducing the payback time for an affordable investment.
SPEctRUM explored a hybrid structural-plus-energy retrofitting solution that combines inorganic textile-based composites with thermal insulation systems for URM buildings to meet all these needs. Analytical models, design solutions and a large-scale investigation across Europe were carried out to boost the implementation of the proposed system.
The emerging need to upgrade and protect traditional masonry buildings both in terms of structural safety and thermal efficiency, highlighted also by current EU and national legislation, was addressed in this Fellowship by exploring the seismic retrofit by means of TRM jacketing combined with thermal insulation materials (Fig. 1). To allow for a wider investigation, numerical models were developed (Fig. 3), which assess the performance of this integrated retrofitting concept at different EU cities and showed that the hybrid system can highly benefit cities especially with a high seismic hazard (Fig. 4).
Specifically, a new implicit model to simulate the mechanical behaviour of TRM-strengthened walls has been developed which includes an empirical rule for the debonding of the textile and a homogenisation model for masonry. The homogenisation model encompasses the gradient elasticity theory to account for the internal microstructure of masonry (Fig. 2). The debonding relationship has been based on the fib model code and adapted accordingly for the interface of textiles in mortar. Using this implicit simulation with the debonding relationship and the homogenisation model, a parametric analysis has been carried out applying a range of textile strength. The analysis has shown that TRM jackets can effectively enhance the out-of-plane capacity of walls. Even when low capacity fibres are used, a considerable out-of-plane increase of the capacity is recorded which becomes much higher for higher strength fibres. The effect of a combined retrofit across Europe together with an increased renovation rate has been shown not only to meet the emission reduction targets but also to be economically feasible, as reduced losses from energy costs and seismic damage make the renovation strategies more viable with short payback periods in high seismicity areas. A scale for combined savings has been proposed showing the advantageous savings of the combined retrofit (Fig. 4).
The EU policy for energy efficiency, sustainability and safeguarding of cultural heritage is benefitted by the project as this can be a useful tool for their implementation efficiently and affordably. The scientific results, methods and perspectives of SPEctRUM have been communicated to a wide audience to raise public awareness and understanding of the benefits of the proposed retrofit technique in renovating the building stock. Various groups have been targeted: (i) the scientific community, (ii) the construction industry and professional organizations, (iii) European fora, and (iv) young scientists, university students, and school pupils. Three main disseminating activities have been used: 1) Oral dissemination: 2 presentations in international conferences (a. EURODYN 2020, XI International Conference on Structural Dynamics, b. The Sixteenth International Conference on Civil, Structural & Environmental Engineering Computing, Italy, 2019), 3 presentations to universities across Europe giving seminars (the University of Thessaloniki, the University of Thessaly, the University College London), 1 lecture to an engineer association (Corfu, Greece), 1 school visit (European school of Varese, Italy). 2) Written dissemination: 2 peer-reviewed conference articles as mentioned above (10.47964/1120.9209.20157 10.13140/RG.2.2.23198.36167) 3 journal papers: 2 in Engineering Structure (one under review and https://doi.org/10.1016/j.engstruct.2020.110311) and Energy and Buildings (https://doi.org/10.1016/j.enbuild.2020.110024) 1 Technical Report published by JRC (under review). All scientific publications are published in open access allowing the widest dissemination. 3) Multimedia dissemination: A website updated regularly was launched (https://spectrummcproject.webnode.gr/) and a blog on the ‘JRC Connection’ site. Moreover, social media and portals such as LinkedIn and Research Gate were used for posting news and information about SPEctRUM.
The emerging need to renovate and protect traditional masonry buildings both in terms of structural and thermal upgrading addressed also by current EU and national legislation is faced here proposing a combined retrofit system (Fig. 1). The application of the combined retrofit has been systematically studied carrying out analytical, numerical and parametric investigations. New analytical models have been proposed: (i) a new homogenisation model for masonry mechanical properties allowing a more practical simulation (Fig. 2), (ii) a new debonding relationship which permits the indirect simulation of the debonding phenomena between the textile and the surrounding mortar, and (iii) an implicit and an explicit model (Fig. 3). Using the latter models, it has been shown that the proposed retrofit technique to be advantageous as it offers substantial strength capacity to URM walls, sufficient energy insulation and sufficient occupant protection from explosions. Applying an analysis at city-scale across Europe it has been shown that the combined retrofit achieves considerable annual loss savings and short payoff times especially in high seismicity areas (Fig. 4). The results and the conclusions of the project were several steps beyond the state-of-the art of the retrofit of masonry buildings showing the efficacy (examining various materials and different loads) and viability (in terms of payoff time) of the retrofit technique and can be useful to various target audiences such as the engineering community (applying the proposed techniques, models and methodologies), the researchers (deepening the developed knowledge), the policymakers (taking advantage of the conclusions) and the industry (developing products for the refurbishment of buildings market).
Stress analysis: (a) the Discrete finite element modelling, or (b) using homogenised properties.
URM annual savings for an energy or a combined retrofit for various seismic and climatic zones.
Experimental failure mode and finite element model response.
Sketch of combined retrofit for URM: (a) TRM and insulation, or (b) insulation and TRM externally.