Explore the vast range of titles available.

Timber structures and structural members have undergone rapid development in recent decades and are now fully competitive with traditional structures made of reinforced concrete or structural steel in many areas. Low self-weight, high durability, rapid construction assembly, and a favourable environmental footprint predispose timber structures for wider future use. A persisting drawback is the often-complicated joining of individual elements, especially when moment resistance is required. For CLT panels, this issue is more urgent due to their relatively small thickness and cross-laminated lay-up. This paper presents experimental research investigating parameters related to the actual behaviour of a moment-resisting embedded joint of CLT panels. The test programme consisted of four series (12 specimens) loaded in four-point bending to failure. The proposed and tested joint consists of high-strength steel rods glued into the two connected parts of the CLT panel. In addition to a detailed investigation of the resistance and stiffness of the joint, this research evaluates the effect of composite action with a reinforced-concrete slab on the performance of this type of joint. The experimental results and their detailed analysis are also extended to propose a framework concept for creating a theoretical (mechanical) model based on the component method.

The Italian building heritage is aged and inadequate to the high-performance levels required nowadays in terms of energy efficiency and seismic response. Innovative techniques are generating a strong interest, especially in terms of multi-level approaches and solution optimizations. Among these, Nested Buildings, an integrated intervention approach which preserves the external existing structure and provides a new structural system inside, aim at improving both energy and structural performances. The research presented hereinafter focuses on the strengthening of unreinforced masonry (URM) buildings with cross-laminated timber (CLT) panels, thanks to their lightweight, high stiffness, and good hygrothermal characteristics. The improvement of the hygrothermal performance was investigated through a 2D-model analyzed in the dynamic regime, which showed a general decreasing in the overall thermal transmittance for the retrofitted configurations. Then, to evaluate the seismic behavior of the coupled system, a parametric linear static analysis was implemented for both in-plane and out-of-plane directions, considering various masonry types and connector spacings. Results showed the efficiency of the intervention to improve the in-plane response of walls, thus validating possible applications to existing URM buildings, where local overturning mechanisms are prevented by either sufficient construction details or specific solutions.

This study aimed to investigate the effects of wood species and lumber quality grades on the mechanical properties and costs of cross-laminated timber (CLT) panels. Various combinations of lumber with different quality grades were utilized in the layers to identify the optimal configurations for producing CLT panels with high mechanical performance and low costs. In the study, spruce and Scots pine lumber of three different quality grades (Grades 1, 2, and 3), classified according to TS 1265 standards, were used. Some mechanical properties of the CLT panels produced from lumber of varying quality grades were determined following the TS EN 408 standard. Additionally, cost analyses of the CLT panels were conducted based on the calculation of raw material costs. The results show that while higher-grade lumber improves mechanical performance, lower-grade combinations still can meet structural needs at lower costs. Mixed-grade configurations offer a balance between strength and affordability. These findings can help CLT producers optimize material selection and reduce costs while maintaining structural integrity. Using lower-grade lumber can address shortages and reduce reliance on expensive timber. Policymakers can promote sustainable forestry and lower production costs, making mass timber construction more viable and environmentally sustainable.

In the present paper, an integrated intervention system applicable to concrete-framed buildings is presented. The purpose of the intervention is to improve both the seismic and the energetic behaviour of such buildings using cross-laminated timber (CLT) panels. Two alternative intervention configurations with different levels of invasiveness are described. Considering a double-wythe masonry-infilled frame, the most invasive configuration consists in the replacement of the external masonry wythe with the CLT panel, while the least invasive configuration consists in the arrangement of the CLT panel from the outside without removing the wythes. The technical details and implementation procedures were studied, considering functionality and disturbance to occupants. An isolated one-storey-one-bay frame was used as a reference for the seismic and thermal analyses. Subsequently, the two intervention configurations were applied to a case-study building by identifying two alternative intervention strategies. The obtained results showed that the proposed integrated intervention approach can significantly reduce both the seismic vulnerability and the energy consumption of concrete buildings.

Timber structures are currently more important for solving tasks in construction practice. For this reason, there is an opportunity for research in the area of physical tests and numerical models. This paper deals with the determination and comparison of the deformation properties of cross-laminated timber (CLT) panels based on laboratory tests, analytical calculation and numerical modeling. CLT panels are structural building components consisting of cross-oriented solid timber layers. Three types of panels with different geometry and number of layers (three, five and seven) were experimentally tested using a four-point bending test, where load–deformation curves were recorded. The results of the experimental testing of the three-layer panels were subsequently compared with a numerical model in SCIA Engineer, a numerical model in ANSYS Workbench and an analytical calculation. The research shows a good agreement in bending behavior between the laboratory tests, the analytical calculation according to the standard and two different approaches in numerical analysis.

Cross laminated timber panels (CLT) are promising building structures that are actively used in the construction of buildings around the world. In Russia the construction is rarely used, despite the existing factories for their manufacturing. In regulatory documents there are no specific data on the elastic modulus for these structures. As a method for determining this calculated characteristic, a numerical experiment in the SCAD Office software package is proposed. During the experiment, panels of various thickness and different numbers of layers are considered. Based on the obtained displacements from the action of the applied load, the values of the elastic modules are determined and summarized in the table. According to the results of the calculation, graphs of dependences of the reduced elastic modules on the thicknesses and the number of layers are constructed and analyzed.

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.

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 study presents analytical solutions grounded in three-dimensional (3D) thermo-elasticity theory to predict the bending behavior of cross-laminated timber (CLT) panels under thermo-mechanical conditions, incorporating the orthotropic and temperature-dependent properties of wood. The model initially utilizes Fourier series expansion based on heat transfer theory to address non-uniform temperature distributions. By restructuring the governing equations into eigenvalue equations, the general solutions for stresses and displacements in the CLT panel are derived, with coefficients determined through the transfer matrix method. A comparative analysis shows that the proposed solution aligns well with finite element results while offering superior computational efficiency. The solution based on the plane section assumption closely matches the proposed solution for thinner panels; however, discrepancies increase as panel thickness rises. Finally, this study explores the thermo-mechanical bending behavior of the CLT panel and proposes a modified superposition principle. The parameter study indicates that the normal stress is mainly affected by modulus and thermal expansion coefficients, while the deflection of the panel is largely dependent on thermal expansion coefficients but less affected by modulus.

This study is dedicated to the production of Cross-Laminated Timber (CLT) panels using pine wood, treated through in situ polymerisation with raw pine resin, with a primary focus on evaluating their resistance against termite attacks. The effectiveness of the treatment was assessed based on density gain. The CLT specimens underwent exposure to subterranean termites through a choice feeding test, and subsequent mass losses were meticulously documented. Mechanical behaviors, both pre and post-termite attack, were comprehensively analyzed through tensile and compression tests. The treatment demonstrated a notable increase in termite resistance, resulting in significantly larger compressive properties. While tensile properties exhibited comparable averages between treated and untreated specimens, the treatment showcased its efficacy in preserving the mechanical integrity of CLT. Treated specimens retained their mechanical properties in both compression and tension even after termite attacks, in stark contrast to untreated counterparts, which displayed a significant impairment in their properties. These findings underscore the potential of in situ polymerisation with raw pine resin as an efficient method to bolster termite resistance and safeguard the mechanical strength of CLT panels. The study contributes valuable insights for the construction industry, especially in regions where termite infestation poses a significant challenge to wooden structures, emphasizing the promising application of environmentally friendly treatments in enhancing the durability of construction materials.