Search Results (27)

The increased interest in tall timber buildings has led to the need for more accurate prediction models. With inherently low mass and stiffness properties, multi-story buildings made of timber are susceptible to wind-induced vibrations, which can result in discomfort for the occupants. Multiple experimental and numerical studies investigating natural frequencies and mode shapes of timber buildings can be found in the literature. However, modeling the damping properties in timber buildings has not been studied fully yet. This study presents a framework for the estimation of the global damping ratio of glue–laminated-frame buildings by use of linear-elastic finite element modeling. Using stiffness-dependent Rayleigh damping and the dynamic analysis in the time domain, it was demonstrated that the predictions of the FE model for the damping ratio were within the range of the results obtained by on-site measurements. The case study of the tallest all-timber building in the world (Mjøstårnet, Norway) was used to demonstrate the framework using extensive small- and large-scale experimental data. The parametric study identified the damping ratio in the diagonals and material damping ratio in the glue–laminated timber as the key parameters influencing the damping ratio of the whole building. Full article

Timber–concrete hybrid structures are commonly employed in multi-story timber buildings; however, further research is necessary to fully understand the seismic performance of these structures as well as the dynamic properties of the floor. The two dynamic concerns, seismic effects and the vibration of floors in hybrid structures, are key issues, in view of which this study aimed to investigate the small-seismic-response spectra and elastic time histories in a high-rise timber hybrid building, specifically the medical technology building of Jiangsu Provincial Rehabilitation Hospital in China. The dynamic characteristics of a localized cross-laminated timber (CLT) floor were tested in situ, and the impacts of human-induced vibration were quantified. Comprehensive theoretical analysis results reveal that the basic vibration pattern of the structure was mainly translational in nature and that the period ratio, inter-story displacement angle, and shear-to-weight ratio all met the demands of the Chinese timber building design code. The experimental test results show that the vertical natural frequency of the CLT floor was about 15.96 Hz and thus met appropriate requirements with respect to natural frequency. However, peak floor acceleration was found to be high under the conditions of a single person walking quickly, a single person trotting, and multiple persons walking randomly. In light of these findings, the floor should be paved with a fine-grained concrete building surface, according to design requirements, so that its serviceability might be improved. Overall, the relevant analytical methods presented in this paper provide guidance and practical reference for the seismic analysis of timber hybrid structures, as well as vibration serviceability analysis for CLT floors. Full article

To date, the existing literature lacks any studies that compare timber and concrete apartment buildings in the Finnish context regarding their carbon footprint, handprint, and the cost of frame structures. This study rigorously analyzes and calculates the carbon footprint, carbon handprint, and costs associated with various structural solutions in a proposed multi-story building located in Laajasalo, Helsinki, Finland. While the primary focus is on wooden frame construction, exploring both its challenges and opportunities, this study also includes a comparative assessment with concrete frame construction. In Finland, regulations require a sprinkler fire extinguishing system to be installed inside. Also, weather protection is typically added to the top of building in connection with the construction of wooden apartment buildings. When the costs of a sprinkler system and weather protection are taken into account, the cost of achieving positive climate effects through a concrete frame is 290% higher than that of a solid wood frame. Our findings will provide a robust basis for assessing the sustainability and feasibility of construction methods, offering valuable insights into environmental and economic considerations for decision-makers in Finland and beyond as regulations evolve and awareness of climate impacts grows. Full article

In the Changxi River Basin in eastern Fujian, a few stone elements remain and Buddhist buildings with one bay in width and three bays in depth have been preserved dating from the timespan of the Tang to the Song dynasty. These features are characterized by a regional form of early Buddhist architecture seldom seen in Chinese history. The article focuses on the reconstruction of a Song dynasty Buddhist building at the Gonghoulou Temple site in Huotong Town, Jiaocheng District, Ningde City, and aims to analyze the potential characteristics and rules of single-bay Buddhist architecture. From the styles of the remaining stone columns, the direction of the lotus carving at the column base, and the mortises of the plinth stone, a spatial arrangement is indicated that includes an open front corridor and a closed rear section. A “reconstruction” of the ruler used in the original building reveals the possibility that a local Fujian ruler was used, shorter than the standard measurement device employed elsewhere. The analysis of the frame construction indicates that this hip-gable roof-covered Buddhist hall utilizes the horizontally layered logic of multi-storied palatial-style halls. Key elements include its gentle roof slope, restraint from the practice of shortening the roof ridge, use of the traditional chuji method, and the interior columns use of internal longitudinal architraves secured to beam supporting brackets. This research brings to light a unique architectural type that has disappeared in the course of history and was previously unknown to the academic community. It holds significant importance and value for deepening the understanding of the history of timber frame architecture technology in Fujian. Full article

Modular timber construction embodies a pioneering and eco-friendly methodology within the building sector. With the notable progress made in manufacturing technologies and the advent of engineered wood products, timber has evolved into a promising substitute for conventional materials such as concrete, masonry, and steel. Beyond its structural attributes, timber brings environmental advantages, including its inherent capacity for carbon sequestration and a reduced carbon footprint compared to conventional materials. Timber’s lightweight nature, coupled with its versatility and efficiency in factory-based production, accelerates modular construction processes, providing a sustainable solution to the growing demands of the building industry. This work thoroughly explores contemporary modular construction using wood as the primary material. The investigation spans various aspects, from the fundamentals of modularity and the classification of modular timber solutions to considerations of layout design, structural systems, and stability at both the building and module levels. Moreover, inter-module joining techniques, MEP (mechanical, electrical, and plumbing) integration, and designs for disassembly are scrutinized. The investigation led to the conclusion that timber modular construction, drawing inspiration from the steel modular concept, consistently utilizes a structural approach based on linear members (timber frame, post-and-beam, etc.), incorporating stability configurations and diverse joint techniques. Despite the emphasis on modularization and prefabrication for adaptability, a significant portion of solutions still concentrate on the on-site linear assembly process of those linear members. Regarding modularity trends, the initial prevalence of 2D and 3D systems has given way to a recent surge in the utilization of post-and-beam structures, congruent with the ascending verticality of buildings. In contrast to avant-garde and bold trends, timber structures typically manifest as rectilinear, symmetric plans, characterized by regular and repetitive extrusions, demonstrating a proclivity for centrally located cores. This work aims to offer valuable insights into the current utilization of modular timber construction while identifying pivotal gaps for exploration. The delineation of these unexplored areas seeks to enable the advancement of modular timber projects and systems, fully leveraging the benefits provided by prefabrication and modularity. Full article

In recent years, the use of timber as a building material in larger construction applications such as multi-story buildings and bridges has increased. This requires a better understanding of the material to realize such constructions and design them more economically. However, accurate computational simulations of timber structures are challenging due to the complexity and inhomogeneity of this naturally grown material. It exhibits growth inhomogeneities such as knots and fiber deviations, orthotropic material behavior and moisture dependence of almost all physical parameters. Describing the creep response of wood under real climate conditions is particularly difficult. Changes in moisture content, plasticity and viscoelasticity affect moisture-induced stresses and potentially lead to cracks and structural damage. In this paper, we apply a material model that combines time and moisture-dependent behavior with multisurface plasticity to simulate cross-sections of different dimensions over a 14-month climate period. Our findings indicate that considering this long-term behavior has a minor impact on moisture-induced stresses during the drying period. However, during the wetting period, neglecting the time- and moisture-dependent material behavior of wood leads to a significant overestimation of tensile stresses within the cross-section, resulting in unrealistic predictions of wetting-induced fracture. Therefore, simulations during wetting periods require a sophisticated rheological model to properly reproduce the stress field. Full article

Driven by climate change and the need for a more sustainable construction sector, policy is increasingly demanding and promoting timber hybrid construction methods. In the German state of Baden-Württemberg, every new public building has to be of timber or timber hybrid construction (Holzbauoffensive BW). The objective of multi-story buildings with large floor spans can only be achieved in a resource-efficient way by hybrid constructions combining timber and steel components. A research project recently completed at the Karlsruhe Institute of Technology was aimed at the development and systematic investigation of hybrid bending beams in which an advantageous combination of the materials steel and timber is used. For this purpose, steel profiles are integrated into timber cross-sections in a shear-resistant manner by adhesive bonding. As part of the experimental, numerical and analytical investigations, different cross-sections of steel and timber, as well as different construction materials, were considered (GL24h, LVL48p, LVL80p, S355 and S420). The results of large-scale four-point bending tests illustrate the potential of this new hybrid construction method. Depending on the geometry and material combinations tested, the bending stiffness could be increased by up to 250%, and the load-carrying capacity by up to 120%, compared to a glulam beam with identical dimensions. Full article

Floor vibration, although not a safety concern, is a prevalent performance complaint in multi-story structures. With the increasing use of mass timber construction, various types of long-span timber floors (LSTFs), including plain cross-laminated timber (CLT), CLT with secondary beams (ribbed-deck), and hybrid systems such as timber–concrete composite (TCC) and CLT on-steel-support beams, are gaining popularity. However, due to limited knowledge regarding their vibration characteristics and acceptance criteria, these construction types are often overlooked during the design stage by architects, engineers, and builders. Existing standards and guidelines primarily calibrated for steel and concrete floors lack a validated and calibrated method for evaluating the vibration performance of LSTFs. Nonetheless, it is essential for structural engineers to address vibration concerns during the design stage and potentially investigate excessive vibration in existing buildings, providing mitigation solutions. This article provides a comprehensive overview, discussion, and analysis of the measurement, analysis, design, perception, and acceptability of vibration of timber floors as outlined in international standards and commonly used guidelines. Experimental and theoretical case studies, including vibration measurements of a CLT floor and a comparison of vibration acceptability in lightweight timber floors using different methods, are reported. The results highlight discrepancies between simplified equation calculations and modal analysis observations, underscoring the limitations of relying solely on simplified equations. Furthermore, it is observed that current modal superposition methods tend to be conservative in predicting floor acceleration and velocity responses. Recommendations are provided for future research in the field to enhance floor vibration assessment techniques, aiming for improved design optimization and occupant comfort. Full article

To reduce carbon emissions, holistic approaches to design, plan, and build our environment are needed. Regarding multi-story residential buildings, it is well-known that (1) material choices and construction typologies play a fundamental role in the reduction of carbon footprint, (2) shifting from concrete to timber will reduce significantly the carbon footprint, and (3) a building designed to be disassembled will increase the potential of achieving zero-carbon emissions. However, little has been said about the consequences of such shifts and decisions in terms of building architecture and structural design, especially in seismic-prone regions. In this study, an existing 9-story reinforced concrete (RC) multi-story residential building is redesigned with cross-laminated timber floors and glue-laminated timber frames for embodied carbon reduction purposes. Firstly, the reasons behind design decisions are addressed in terms of both architecture and structure, including the incorporation of specially steel concentrically braced frames for seismic-resistance. Then, the outcomes of life cycle assessments and pushover analyses show that the RC residential building emits two times more carbon than the hybrid steel-timber residential building, and that while the hybrid building’s lateral load-capacity is less than in the RC building, its deformation capacity is higher. These results highlight the relevance of considering the carbon footprint in combination with the design decisions, which seems to be the key to introducing circular projects in seismic-prone areas. Full article

In recent years, the performance of the construction industry has highlighted the increased need for better resource efficiency, improved productivity, less waste, and increased value through sustainable construction practices. The core concept of sustainable construction is to maximize value and minimize harm by achieving a balance between social, economic, technical, and environmental aspects, commonly known as the pillars of sustainability. The decision regarding which structural material to select for any construction project is traditionally made based on technical and economic considerations with little or no attention paid to social and environmental aspects. Furthermore, the majority of the available literature on the subject considered three sustainability pillars (i.e., environmental, social, and economic), ignoring the influence of technical aspects for overall sustainability assessment. Industry experts have also noted an unfulfilled need for a multi-criteria decision-making (MCDM) technique that can integrate all stakeholders’ (project owner, designer, and constructor) opinions into the selection process. Hence, this research developed a decision support system (DSS) involving MCDM techniques to aid in selecting the most sustainable structural material, considering the four pillars of sustainability in the integrated project delivery (IPD) framework. A hybrid MCDM method combining AHP, TOPSIS, and VIKOR in a fuzzy environment was used to develop the DSS. A hypothetical eight-story building was considered for a case study to validate the developed DSS. The result shows that user preferences highly govern the final ranking of the alternative options of structural materials. Timber was chosen as the most sustainable option once the stakeholders assigned balanced importance to all factors of sustainable construction practices. The developed DSS was designed to be generic, can be used by any group of industry practitioners, and is expected to enhance objectivity and consistency of the decision-making process as a step towards achieving sustainable construction. Full article

Cross-laminated timber (CLT) has been widely discussed as a relevant industrialized construction solution. Numerous publications have considered CLT as a structural wood-based panel, but other documents have mentioned it as a building or even a construction system. Many authors address its application in multistory buildings, although single-family houses and lower building applications have become desirable topics as well. Given these gaps, this review study addresses a systematic method to evince the functions of cross-laminated timber in construction. The elucidation and discussion were led by technical and scientific contents through publications present in scientific websites and the Google web search engine. Intricate perceptions about the knowledge and reference of CLT functions were identified. From prospections, it was possible to state that CLT is a timber-forest product created in Europe, whose function acts as a structural composite panel of the engineered wood product category. However, CLT has been mentioned by many publications as a building or a construction system. Suggestions were raised to clarify to all readers with respect to misconceptions, and elucidate the construction systems capable of using it as the main resource. Discussions evinced the characteristics and potentials of this wood product. Even with its increasing application in tall buildings, the commercial application of CLT in low-rise buildings may be boosted by the possibility of large-scale production of industrialized houses. Full article

This study aims to understand the views and experiences of Tampere residents in Finland about multi-story timber-framed apartments and wooden structures through a questionnaire. The 151 responses highlighted two main issues: (1) multi-story timber-framed apartments were rated as a good product in terms of user satisfaction, which was based on the following findings: (1a) for most of the respondents, the apartment had fresh air and a suitable temperature on cold winter days; (1b) the majority felt safe living in a multi-story timber-framed apartment; (1c) respondents generally were satisfied with the soundproofing, except for the disturbing noises from the upper floor and the stairwells; (1d) residents’ opinions were mainly positive regarding most of the functional features such as storage facilities, the location and access roads of the building, exterior facade, and wood visibility level; (2) there exists a demand for multi-story timber-framed residential buildings in the market, especially in the customer segment, which is defined as ‘environmentalist’. This was based on the following findings: (2a) living in an environmentally friendly, low-carbon, natural-material apartment, cozier living in a timber-framed apartment, and meaningful use of wood in interiors were notably more important for the extremely satisfied residents; (2b) building facades, and floors and ceilings inside the apartment were the places where the use of wood was most desired in the apartment. This article is intended to be a guide for key construction experts, e.g., architectural designers and developers to better understand and meet the demands and needs of timber-framed apartment residents in Finland. Full article

Fire safety greatly contributes to feeling safe, and it is a key parameter for the selection of building materials. The combustibility of timber is one of the main reasons to have the strict restriction on timber for use as a building material, especially for multistory buildings. Therefore, the main prerequisite for the use of timber in buildings is to ensure adequate fire resistance, using passive and active fire protection measures. This article contains the results of mechanical and fire experimental tests of both normal and innovative hollow glued laminated timber beams. A total of 10 timber beams were tested at ambient temperature, and 3 timber beams in fire conditions, which differed in cross-section type but also in the applied fire protection. The first beam was a normal GL beam without fire protection, the second a hollow beam covered by intumescent paint, while the third was also hollow, additionally protected by mineral wool infill inside the holes. The load-carrying capacity of the hollow beam in ambient conditions was estimated at 65% of the load-carrying capacity of a normal GL beam. Fire tests indicated that hollow timber beams with both intumescent paint and mineral wool infill failed at a similar time as a normal GL beam without fire protection. One-dimensional β₀ and notional charring rates β_n were obtained. Time to the protective material failure was 17 min. The main cause of failure of hollow beams was the appearance of delamination due to the reduction of the lamella bonding surface. Full article

Cross-laminated timber (CLT) floors with supplementary layers or floating floors comprise a common solution in new multistory timber structures. However, bare CLT components provide poor sound insulation, especially in low frequencies during structure-borne sound propagation. Thus, floor configurations in wooden buildings deploy more layers for improved acoustic behavior. Twelve contemporary CLT floors were analyzed after laboratory measurements of airborne sound reduction and impact sound transmission utilizing the following indicators: $R_w$, $R_{w, 100}$, $R_{w, 50}$, $L_{n,w}$, $L_{n,w,100}$, and $L_{n,w,50}$ (per ISO 10140, ISO 717). An increase in sound insulation was achieved thanks to added total mass and thickness, testing layers of the following: elastic mat for vibration isolation, wool insulation, gypsum boards, plywood, concrete screed, and wooden parquet floor. The results indicate that multilayered CLT floors can provide improvements of up to 22 dB for airborne sound and 32 dB for impact sound indicators compared with the bare CLT slab. Floating floor configurations with dry floor solutions (concrete screed) and wooden parquet floors stand out as the optimal cases. The parquet floor provides a 1–2 dB improvement only for impact sound indicators in floating floor setups (or higher in three cases). Full article

The use of parametric and multi-objective optimization (MOO) as a new way of approaching architectural design has been growing in line with current breakthroughs in computational architecture. Wood, on the other hand, is a living and unique building material that provides durability, manufacturing flexibility, and local availability. One of the structure types that provides high structural stability is the hyperboloid. However, the exploration of hyperboloid structures in building design, together with the building daylight objective, is still limitedly reported. This paper presents the application of the parametric approach and multi-objective optimization in optimizing the structure and daylight objectives of a hyperboloid two-story wooden house in Japan, made of 105 mm × 105 mm × 4000 mm Japanese timber. The method involves iterating dynamic parameters such as radius bottom, offset distance, timber members, twisting level, building height, radius-top, and roof slope to optimize the structural objective of minimizing normal force average, displacement, and cost while simultaneously maximizing building volume. Regarding daylight objectives, unit movement and glazing ratio that control the glazing strategies were explored to optimize useful daylight illumination (UDI) in summer and winter. The optimization and exploration yielded 10,098 solutions in structural analysis and 406 solutions in daylight exploration. Based on the data analysis, the proposed methodology has successfully produced the best design solution, discovering the balance between the objective trade-offs. In addition, the most influential parameter that shapes the value of design objectives has been identified. The findings of this research were expected to contribute to and enhance the performance-based design optimization, and support design decision-making process in the early design stage of a wooden house with a hyperboloid structure. Full article