In order to reach the ambitious decarbonizing goals set by the European Union for 2030, deep renovation of the existing European building stock is a key issue. Within this context, the recently ...funded H2020 project “e-SAFE” is investigating market-ready wooden envelope renovation solutions for non-historic buildings, which encompass both energy and seismic improvement. The research carried out in the project aims at developing, testing and demonstrating these solutions on a real pilot. More specifically, this paper presents preliminary analyses to verify that the solutions satisfy the requisites set by the national regulations in force in most European countries, in terms of hygrothermal and acoustic performance. The analysis, carried out following relevant technical European Standards and based on calculations, considers different climate conditions and existing wall structures, selected amongst those most commonly adopted in Europe. The results show that the addition of a Cross Laminated Timber (CLT) layer with some wooden-based insulation on the outer side allows reaching very good thermal and acoustic performance. However, interstitial condensation may occur in cold climates under high indoor humidity values. This aspect deserves further investigation accounting for the transient behavior of the walls and all vapor transport mechanisms.
This paper deals with the influence of the rolling shear deformation on the flexural behavior of CLT (Cross-Laminated Timber) panels. The morphological configuration of the panels, which consist of ...orthogonal overlapped layers of boards, led to a particular shear behavior when subjected to out-of-plane loadings: the low value of the shear modulus in orthogonal to grain direction (i.e., rolling shear modulus) gives rise to significant shear deformations in the transverse layers of boards, whose grains direction is perpendicular with respect to the tangential stresses direction. This produces increases of deflections and vibrations under service loads, creating discomfort for the users. Different analytical methods accounting for this phenomenon have been already developed and presented in literature. Comparative analyses among the results provided by some of these methods have been carried out in the present paper and the influence of the rolling shear deformations, with reference to different span-to-depth (L/H) ratios investigated. Moreover, the analytical results have also been compared with those obtained by more accurate 2D finite element models. The results show that, at the service limit states, the influence of the rolling shear can be significant when the aspect ratios became less than L/H = 30, and the phenomenon must be accurately considered in both deflection and stress analysis of CLT floors. Contrariwise, in the case of higher aspect ratios (slender panels), the deflections and stresses can be evaluated neglecting the rolling shear influence, assuming the layers of boards as fully-connected.
The structural behaviour of mass timber buildings under a load bearing element removal scenario is complex. To well understand this phenomenon and ultimately develop scientifically based design ...guidelines against progressive collapse for this type of buildings, there is a need to develop a Finite Element model which accurately captures the non-linear response, load redistribution mechanisms (alternative load paths) and failure modes of such buildings. As such, this paper presents for the first time how mass timber post-and-beam systems can be accurately modelled using Finite Element under edge and corner column removal scenarios. The model was validated against published 2D and 3D experimental tests performed on scaled-down substructures. The non-linear structural responses of the main structural connections were experimentally quantified and inputted into the model using the component method. Results show that the model accurately replicated load redistribution mechanisms, ultimate loads, failure modes, and strain developments. The use of the model was then illustrated by running parametric studies to quantify (i) the influence of the Cross Laminated Timber (CLT) floor panels layout and (ii) one alternative load path, typically ignored in design, on the progressive collapse resistance capacity.
•A FE model of mass timber post-and-beam timber buildings is detailed.•The accuracy of the model was verified against experimental tests.•The model allows the understanding of mass timber buildings under accidental loads.•The use of the model is illustrated by finding the influence of several alternative load paths.
People have erected buildings with the use of timber structures for a long time. The uses of timber constructions are very diverse—it is used for the production of exterior wall and roof ...constructions, window frames and doors, and it is used for dry as well as wet premises. Scandinavian countries have extremely vast experience of using timber structures. Latvia has a rather extensive timber processing and timber structure manufacturing sector. Many companies are involved in timber processing, however, to enable even more extensive use of timber structures, environmental and technically economic requirements of contemporary building must be taken into consideration. Environmental requirements for timber structures provide certain advantages in comparison to other building materials, but technically economic requirements are very important as well. The development of manufacturing of glued constructions and research of production processes of these constructions allows one to find solutions for the reduction in the cost of timber structures, and the results of such research can ensure significant development of the use of timber structures in building, as well as reduce total construction costs. The basic objective of the study is to investigate the residual materials arising as a result of processing cross-laminated timber constructions (CLT panels), material generated as a result of high levels of construction production, and research of the opportunities to reprocess the residual materials generated as a result of laminated timber structure manufacturing into materials suitable for production of building constructions. The majority of CLT panels are manufactured using 20, 30 and 40 mm thick boards, and, during the panel manufacturing process, there are various standard thicknesses of panels, for example, 60, 80, 100, 120, 140, 160 mm, etc. Various layers are used for the creation of various thicknesses depending on the necessary technical properties. Various arrangements of the thickness of a single panel will cause different structural and physical behaviour (i.e., impact of changes in moisture, fire resistance, etc.). During the research and for the purposes of testing of CLT panels, only residues with equal types and thicknesses of lamellae were selected. Two main purposes were included in the panel testing process: (1) Comparison of technical performance of the residues of CLT panels with the classic CLT panel. Curve strength and tensile strength tests were performed in accordance with LVS EN standards (LVS EN 16351: 2016 and LVS EN 408 + A1: 2012). All the samples were prepared according to the LVS EN standards. (2) To assess the impact of two resins (melamine urea formaldehyde (MUF) and polyurethane (PU)), widely used in industry, on structural properties of recycled CLT material. Results of the research show that recycling residues of glued wooden constructions may lead to good results, and manufacturing residues of CLT panels may be successfully used in construction and for the reduction in CLT panel manufacturing costs.
Cross laminated timber (CLT) panels have been gaining increasing attention in the construction field as a diaphragm in mid- to high-rise building projects. Moreover, in the last few years, due to ...their seismic performances, low environmental impact, ease of construction, etc., many research studies have been conducted about their use as infill walls in hybrid construction solutions. With more than a half of the megacities in the world located in seismic regions, there is an urgent need of new retrofitting methods that can improve the seismic behavior of the buildings, upgrading, at the same time, the architectural aspects while minimizing the environmental impact and costs associated with the common retrofit solutions. In this work, the seismic, energetic, and architectural rehabilitation of tall reinforced concrete (RC) buildings using CLT panels are investigated. An existing 110 m tall RC frame building located in Huizhou (China) was chosen as a case study. The first objective was to investigate the performances of the building through the non-linear static analysis (push-over analysis) used to define structural weaknesses with respect to earthquake actions. The architectural solution proposed for the building is the result of the combination between structural and architectonic needs: internal spaces and existing facades were re-designed in order to improve not only the seismic performances but also energy efficiency, quality of the air, natural lighting, etc. A full explanation of the FEM modeling of the cross laminated timber panels is reported in the following. Non-linear FEM models of connections and different wall configurations were validated through a comparison with available lab tests, and finally, a real application on the existing 3D building was discussed.
At the moment the human is trying to make the construction as efficient as possible, accelerate and facilitate the introduction of different types of innovations. Therefore, to the fore a new concept ...of prefabrication, which we call modern methods of construction MMC is coming. In this article, 3 prefabricated construction systems were chosen for the analysis of the construction of the family house. It is a system of Europanel SIP technology, CLT panels and ceramic panels. These are systems of euro panels' technology SIP, CLT panels and ceramic panels. The choice of construction systems has taken into account that all three systems fall under the MMC philosophy. Subsequently, selected parameters of individual structural systems were analysed, such as wall thickness, ceiling thickness, bulk density, compressive strength of walls, heat transfer coefficient, reaction to fire, fire resistance, usable area and price on a particular family house project.
The construction industry contributes significantly to the global environmental impacts, with a large amount of energy being consumed and various pollutants being released in the production and ...transportation of construction materials. Environmental evaluation methods can provide a quantified estimation of particular environmental impacts of construction materials, structures or whole buildings. This study aims at environmental evaluation of wooden panel structures with different insulation materials (expanded polystyrene, mineral wool, polyurethane rigid foam, wooden particle board and hemp fibres). Five variants of cross laminated timber (CLT) panel systems were compared using SimaPro software. IPCC method was applied to calculate the share of the material variants to climate change. In addition to the global warming potentials (GWP), basic parameters, such as the values of heat transfer coefficient U, the total thickness of the walls and the total weight of the materials were analysed. The CLT structure with the hemp-based insulation proved the best environmental performance while achieving the lowest GWP.
The so-called inerter is an attracting device that offers a solution to the goal of realizing or improving structural control devices with high mass ratios while avoiding the undesirable increase in ...dead load. The research presented here focuses on evaluating the performance of a fluid inerter in mitigating vertical vibrations of structures that exhibit multi-modal behavior, such as plates. First, a numerical study based on previous experimental data investigates the properties of the connection between the inerter and the structure to be controlled. Considering that a flexible connection has been shown to introduce a linearization effect, while a rigid connection of the inerter to the controlled structure can achieve significant displacement reductions, the influence of these two connection types over different inertance ratios is analyzed. To evaluate the practical suitability of the flexible connection to reduce the inherent nonlinear effects associated with the device, a novel application of the fluid inerter for vibration control in multi-modal structures is presented, exemplified by a cross-laminated timber panel, and compares its control performance with that of a conventional Tuned Mass Damper (TMD). This provides insight into the effectiveness of the inerter in controlling vertical vibrations. In addition, optimization procedures are employed to determine connection parameters that enhance the effectiveness of both the TMD and the inerter in mitigating vertical vibrations.
•Assessment of the connection properties of a fluid inerter.•Experimental testing on a fluid inerter for vertical vibration control.•Performance control comparison with a traditional Tuned Mass Damper.•Optimization of the devices’ for multi-modal structures control.
•The effectiveness of CLT panels for the seismic retrofit of RC buildings is investigated.•Full-scale masonry-infilled RC frames are tested as-built and retrofitted with timber panels.•The ...experimental performance of different CLT-based retrofit configurations is investigated.•Construction details of the timber retrofits and a step-by-step application procedure are reported.
This paper presents the results from an experimental study on an innovative timber-based seismic retrofit solution for existing reinforced concrete (RC) buildings. The intervention aims at enhancing the overall seismic resistance of RC framed structures with a light, cost-effective, sustainable, and reversible approach, allowing possible integration with energy efficiency upgrades. The retrofit technique relies on cross-laminated timber (CLT) panels mechanically connected through steel fasteners to the RC frame. This strengthening technique is investigated experimentally for the first time in this paper. The study examines two intervention configurations with different degrees of invasiveness: the first (RC-TP) involves replacing the existing masonry infill wall with a CLT panel, whereas the latter (RC-TPext) consists in applying the panel to the outer face of the frame. Both retrofit configurations were assessed experimentally through cyclic quasi-static in-plane tests on full-scale single-storey, single-bay RC frames. The frames were identical in geometry and characterised by poor mechanical material properties and steel reinforcement details, promoting the development of a strong-beam-weak-column mechanism. The experiments comprised tests on four specimens: a non-retrofitted masonry-infilled frame employed as a reference specimen and three frames strengthened with CLT panels as infills or externally connected retrofitting elements. The paper presents construction details of the strengthening interventions, demonstrates a step-by-step application procedure, and summarises the main observations from the tests, illustrating the evolution of structural damage, the ultimate failure mode, and the cyclic hysteretic response of the specimens. The experiments showed promising results, proving that both retrofit configurations improved the seismic behaviour of the RC frames considerably. Specifically, the RC-TP and RC-TPext retrofit interventions increased the lateral strength of the reference frame by approximately 169% and 104%, respectively. At the same time, both configurations prevented the shear collapse of the columns.
•CLT panels and tempered glass strips were considered for strengthening timber floors.•The tempered glass strips were either adhesively bonded or screwed to the timber joists.•The procedure was ...evaluated by performing four-point bending tests on old timber floor joists.•A significant increase in the effective bending stiffness was achieved.•The bending test results were compared with analytical and numerical calculation results.
This article deals with the procedure for strengthening existing timber floor joists with CLT panels and additional tempered glass strips. The proposed strengthening procedure was investigated on eight old timber floor joists from the historical Zgornja Polskava manor from Slovenia. The glass strips were adhesively bonded or screwed to the joists, while the CLT panels were screwed to the joists with self-tapping screws. The proposed procedure was evaluated based on four-point bending tests of the joists. The efficiency was determined by comparing the bending test results of the strengthened and unstrengthened joists. The bonded glass strip variant always resulted in a higher load-bearing capacity and a higher effective bending stiffness, while the screwed glass strip also always resulted in a higher effective bending stiffness, but only in some instances increased the load-bearing capacity. The experimental results were compared with analytical and numerical calculation results. The results showed good agreement, despite the joists being visually severely damaged, which was also demonstrated by performing acoustic tomography on a timber joist sample.
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