Seismic and Thermal Retrofitting of Masonry Buildings with Fiber Reinforced Composite Systems: A State of the Art Review

Old masonry buildings represent the largest part of traditional constructions. Generally, they are both seismically vulnerable and thermally dispersive. Therefore, the need for seismic and thermal retrofitting aimed at reducing their vulnerability and environmental impact has motivated research efforts towards sustainable retrofitting solutions. This study presents a literature review of the approaches currently available for masonry retrofitting. Specifically, it highlights the use of fiber in textile form i.e., Textile Reinforcement Mortar (TRM), as Fiber Reinforced Polymer (FRP) and natural fibers (animal and plant sources) to masonry retrofitting. In addition, specific attention is devoted to the integrated (structural and thermal) fiber-based integrated retrofitting techniques that are becoming very important in the last years

Fast and Optimized Calculation of the Cable Pretension Forces in Arch Bridges With Suspended Deck

grant number 2017J4EAYBThis paper presents with an effective and fast approach to the optimization of the pretension forces in arched bridges with suspended deck, which makes use of the influence matrix method (IMM). The given cable-tensioning procedure leads to a linear system of equations with a reduced number of unknowns and can be effectively implemented within active control procedures that handle time-varying loading conditions. This method produces a target bending moment distribution (TBMD) over the structure, which significantly mitigates the state of stress of the deck. Numerical simulations referred to a Nielsen arch bridge illustrate the versatility of the proposed approach when dealing with different loading conditions.publishersversionpublishe

Sustainable Retrofitting Solutions: Evaluating the Performance of Jute Fiber Nets and Composite Mortar in Natural Fiber Textile Reinforced Mortars

Sustainable building materials for integrated (structural and thermal) retrofitting are the need of the hour to retrofit/upgrade the seismic vulnerable and ill-insulated existing building stocks. At the same time, the use of natural fibers and their recyclability could help construct safer and more sustainable buildings. This paper presents three aspects of jute fiber products: (1) the evaluation of the mechanical performance of the jute nets (2.5 cm × 2.5 cm and 2.5 cm and 1.25 cm mesh configurations) through tensile strength tests (with the aim for these to be used in upgrading masonry wall with natural fiber textile reinforced mortars (NFTRM) systems); (2) the hundred percentage recyclability of left-over jute fibers (collected during the net fabrication and failed nets post-tensile strength tests) for the composite mortar preparation; (3) and the evaluation of insulation capacity of the recycled jute net fiber composite mortar (RJNFCM) through thermal conductivity (TC) measurements, when a maximum amount of 12.5% of recycled jute fiber could be added in the mortar mixture at laboratory conditions and with available instruments Notably, when more than the said amount was used, the fiber–mortar bonding was found to be not optimal for the composite mortar preparation. These studies have been carried out considering these products’ applicability for integrated retrofitting purposes. It has been found that the denser mesh configuration (2.5 cm × 1.25 cm) is 35.80% stiffer than the other net configurations (2.5 cm × 2.5 cm). Also, the mesh configuration (2.5 cm × 1.25 cm) shows about 60% more capability to absorb strain energy. TC tests have demonstrated the moderate insulation capacity of these composite mortar samples, and the TC values obtained from the tests range from 0.110 (W/mK) to 0.121 (W/mK)

Thermal characterization of recycled materials for building insulation

The building sector is known to have a significant environmental impact, considering that it is the largest contributor to global greenhouse gas emissions of around 36% and is also responsible for about 40% of global energy consumption. Of this, about 50% takes place during the building operational phase, while around 10–20% is consumed in materials manufacturing, transport and building construction, maintenance, and demolition. Increasing the necessity of reducing the environmental impact of buildings has led to enhancing not only the thermal performances of building materials but also the environmental sustainability of their production chains and waste prevention. As a consequence, novel thermo-insulating building materials or products have been developed by using both locally produced natural and waste/recycled materials that are able to provide good thermal performances while also having a lower environmental impact. In this context, the aim of this work is to provide a detailed analysis for the thermal characterization of recycled materials for building insulation. To this end, the thermal behavior of different materials representing industrial residual or wastes collected or recycled using Sardinian zero-km locally available raw materials was investigated, namely: (1) plasters with recycled materials; (2) plasters with natural fibers; and (3) building insulation materials with natural fibers. Results indicate that the investigated materials were able to improve not only the energy per-formances but also the environmental comfort in both new and in existing buildings. In particular, plasters and mortars with recycled materials and with natural fibers showed, respectively, values of thermal conductivity (at 20 °C) lower than 0.475 and 0.272 W/(mK), while that of building materials with natural fibers was always lower than 0.162 W/(mK) with lower values for com-pounds with recycled materials (0.107 W/(mK)). Further developments are underway to analyze the mechanical properties of these materials

Cooling Methods for Standard and Floating PV Panels

Energy and water poverty are two main challenges of the modern world. Most developing and underdeveloped countries need more efficient electricity-producing sources to overcome the problem of potable water evaporation. At the same time, the traditional way to produce energy/electricity is also responsible for polluting the environment and damaging the ecosystem. Notably, many techniques have been used around the globe, such as a photovoltaic (PV) cooling (active, passive, and combined) process to reduce the working temperature of the PV panels (up to 60 degrees C) to improve the system efficiency. For floating photovoltaic (FPV), water cooling is mainly responsible for reducing the panel temperature to enhance the production capacity of the PV panels, while the system efficiency can increase up to around 30%. At the same time, due to the water surface covering, the water loss due to evaporation is also minimized, and the water evaporation could be minimized by up to 60% depending on the total area covered by the water surfaces. Therefore, it could be the right choice for generating clean and green energy, with dual positive effects. The first is to improve the efficiency of the PV panels to harness more energy and minimize water evaporation. This review article focuses mainly on various PV and FPV cooling methods and the use and advantages of FPV plants, particularly covering efficiency augmentation and reduction of water evaporation due to the installation of PV systems on the water bodies

Performance analysis of a floating photovoltaic system and estimation of the evaporation losses reduction

Our research aims to achieve dual-positive effects in the presented study by raising photovoltaic (PV) panels over the water surface. With this, target experiments were primarily conducted to evaluate the efficiency increments of the PV panel while reducing its operating temperature through passive convective cooling obtained by raising it over water. The following objective was to estimate the reduction in water evaporation due to the shading effect induced by the panel placed inside the same basin. The performance of two PV panels was analyzed, one used for tests, the other as a reference. The characteristic curves were determined under the local environmental conditions of Cagliari, Italy. The true temperature reduction and efficiency gain calculations of panel P1 due to water cooling was achieved via the measured temperatures and calculated efficiencies of panel P2 at environmental conditions. The water height inside the basin was constantly monitored and maintained at approximately 7.5 cm below panel P1, which covered about 17% of the total water surface area. The presence of water underneath P1 leads to its efficiency increment on average by 2.7% (absolute) and about 17.22% (relative). At the same time, temperature of panel P1 dropped by 2.7 °C on average. The comparative water evaporation study conducted with and without P1 inside the basin showed a 30% reduction in water evaporation

Thermo-acoustic building insulation materials fabricated with recycled fibers – Jute, Wool and Loofah

Reducing the environmental impact of construction, one of the most polluting industrial sectors, is essential to combat the climate crisis and, for this purpose, we need to start from natural, recyclable and sustainable materials. In this research, panels fabricated with jute and wool fibers, recycled respectively from jute bags used (end-life) for packaging coffee beans and from old (end-life) mattresses, and panels fabricated with a loofah-clay mix were realized and characterized. Comparative analyses were carried out considering in particular insulating characteristics in terms of thermal conductivity and acoustic performance. The thermal conductivity values obtained for jute fibers panels are always included in the upper range of results available for wool fiber with similar density (about 20 kg/m3), but always the lower range of results available for jute-polyester-polypropylene sandwich composite panels. The results obtained for products with clay are obviously strongly dependent on the percentage of binder (clay) in the mix, the increase of which leads to an increase in density, negatively influencing the results obtained. Also, if from the acoustic point of view, it is not possible to add the contribution of the single layers, the noise insulation calculated for the different materials under test has shown for the single layer the good property to break down the noise

Jute fiber-reinforced mortars: mechanical response and thermal performance

Enhancing energy efficiency and structural capacity are the main objectives of masonry retrofitting. However, a combined enhancement of both aspects is hardly achievable, as they are related to the relevant geometric and physical parameters in a somewhat “competitive” fashion. Therefore, the main focus of this research is to achieve the dual positive effect by improving both thermal insulation properties and structural behavior of composite building materials, also with an eye to sustainability. In this context, jute fibers composite mortars were fabricated by using three different fiber lengths (5 mm,10 mm and 30 mm) and four different fiber percentages (0.5%,1%,1.5% and 2%) with respect to the mortar masses. Unreinforced mortar samples showed fragile collapse during the flexural and compression (with hour-glass shape) tests. Whereas the fiber reinforced mortar samples exhibited higher ductility and strain energy but lower strength. These composite samples present also higher thermal resistance as the fiber percentage increases. Samples with longer fibers (30 mm, in all fiber percentage category) can dissipate more mechanical energy, whereas the samples with shorter fibers (5 mm, in all fiber percentage category) have lower thermal conductivity values, which leads to improving the insulation capacity of the composite samples