Tall mass-timber buildings utilize engineered wood panels to form their main gravity and lateral load resisting systems, which makes them lighter and very flexible. As a result, frequent exposure to ...excessive wind-induced vibrations can cause occupant discomfort and unserviceability due to horizontal floor acceleration and excessive deflection. Therefore, the objective of this and the companion paper is to assess the serviceability performance of tall mass-timber buildings probabilistically. For this purpose, the Alan G. Davenport Wind Loading Chain is adapted as a probabilistic Performance-Based Wind Engineering framework. The framework is applied to quantify the serviceability performance of a 102-m tall mass-timber building. In this paper, a complete tall-mass timber building structural design process is outlined. Wind loads are obtained from aerodynamic wind tunnel tests conducted at the Boundary Layer Wind Tunnel Laboratory at Western University. The design process involves preliminary strength design using the provisions of building codes, design revisions using wind load from wind tunnel tests, and serviceability checks. The structural design of the case study tall mass-timber building considers the axial compression, in-plane-shear, and in-plane and out-of-plane bending moment demands, along with their interactions due to gravity and wind loads. Dynamic analysis is carried out to assess the drift performance of the case study mass-timber building. The results show that the building satisfies the drift requirements prescribed by the building codes with a small safety margin. For the designed tall mass-timber building, an in-depth probabilistic serviceability-performance assessment and vulnerability estimations are presented in the companion paper.
•A complete structural design process of tall mass-timber building is provided.•The design of mass-timber building considered axial, in-plane shear, and in-plane and out-of-plane bending moment demands.•Modified HSK connection systems are used as shear and hold-down connectors.•Wind tunnel testing at 1:200 geometric scale is conducted for two exposure conditions and 36 wind angles of attack.•Drift performance assessment results show that the building satisfies the building code requirements.
Steel and concrete are traditionally used as structural materials for non-residential and multi-housing buildings. However, wood can meet the same structural property requirements, and a variety of ...multi-story buildings have recently been built all over the world using this key material. In this study, the main motivations and barriers to wood adoption for structural uses in non-residential buildings are highlighted, based on an analysis of grey literature concerning some well-known buildings and on scientific literature. The motivations found were linked to sustainability, lack of expertise, costs, rapidity of erection, and aesthetic of wooden structures. In contrast, the barriers preventing its use encompass building code implementation, technology transfer, costs, material durability and other technical aspects, culture of the industry, and material availability. Furthermore, an analysis of non-residential timber building meeting minutes for nine projects is also presented to support the identification of problems and concerns related to site assembly issues, the conception of the building, the scheduling, and stakeholders’ relationships. With a better understanding of the expectations and challenges concerning wood usage in non-residential construction projects, companies will be able to adapt their business models and use the resource even more in the future to develop innovative structures.
Life cycle assessment (LCA) has been widely used to determine the environmental impact of mass timber construction (MTC) as a substitute for conventional construction. This article presents a ...systematic review of MTC from a life cycle assessment perspective. The goal and scope definition, life cycle inventory analysis, impact assessment and interpretation are examined and analyzed in 62 peer-reviewed articles. The results show the variety in scope, lifespan, system boundary, data sources and indicators. Studies on MTC have been conducted at the building material, component, structure, and entire building levels, as well as at the urban level. The majority of studies compare the LCA of reinforced concrete (RC) and cross laminated timber (CLT) buildings. The global warming potential (GWP) and life cycle energy are the most frequently evaluated category indicators among the articles. It is found that the average embodied energy of mass timber buildings is 23.00% higher than that of RC alternatives, while the average embodied greenhouse gas (GHG) emissions of RC buildings are 42.68% higher than that of mass timber alternatives. There is a clear general trend that mass timber buildings generally have lower GWP and life cycle primary energy (LCPE) than RC and steel buildings. Eventually, sensitivity analysis, carbon storage and outlook of the mass timber are also reviewed and discussed in the literature.
An accurate prediction of floor accelerations is crucial for estimating damages to contents and non-structural components in a building. Oversimplifying the nature of acceleration demands might ...result in biased estimates of building damages and, consequently bias in the calculation of economic losses. However, given the relative novelty of multi-storey tall timber buildings, dedicated studies and models of their seismic acceleration demands are lacking. The need for these is stressed further when we recognise that the behaviour of walled timber structures is decidedly different from that of other conventional structural types. In this study, we apply modern data-driven approaches to evaluate efficient intensity measures (IMs) and develop regression models for predicting the peak floor acceleration (PFA) of multi-story cross-laminated timber (CLT) buildings. Twenty-four IMs are evaluated and their prediction performance is compared. The sensitivity of acceleration demands to different IMs over a wide range of CLT buildings is investigated. We perform a systematic feature selection process using three different data-driven techniques. The selected features are then used to develop nine regression models to estimate PFA. Various modelling techniques, consisting of conventional regressions (Linear and Polynomial regressions) as well as machine learning algorithms (Decision trees, Random forest, K-nearest neighbor, and Support vector regression) are used. The dataset used to train the models is obtained from numerical results of 69 CLT building models with variations in building height, panel fragmentation levels, and q-factors (ductility levels) subjected to a large set of strong earthquakes. After assessing the accuracy of our model predictions, the PFA estimates obtained from the proposed models are compared against previous research and design codes. Finally, simplified expressions for estimating peak floor accelerations in CLT structures are provided for practical purposes.
•Nine machine learning models for the prediction of seismic accelerations in tall timber buildings are developed.•Various feature selection algorithms are used to select the best features among candidates to be used as efficient response predictors.•Feature importance and partial dependence plots as well as accumulated local effects provide evidence of the strong linear coupling between PFA and PGA.•The response is markedly different for low and high-intensity earthquakes.•Consistencies and differences between our ML estimations and previous models and code provisions are identified and discussed.
The choice of materials may play an important role in achieving the common European aims of near zero energy demand and greenhouse gas (GHG) emissions in the lifecycle of buildings. The production of ...timber materials demands lower emissions than concrete and steel. To guide political and industrial priorities, it is vital to estimate the emission effects of increased use of timber.The article reports on a broad study that had the following aims: To forecast the number, types, floor area, and location of new buildings that will be built in Oslo and Akershus counties between 2015 and 2030.To estimate how many of these new buildings (a) will be and (b) could be built with timber as the main construction material.To compare these timber potentials to the present and future availability of nationally and sustainably sourced and manufactured timber.To estimate the effect on GHG emissions when substituting concrete and steel with timber in the production of new buildings in Oslo and Akershus counties between 2015 and 2030.The research is based on official prognoses for population growth. They are combined with building predictions derived from municipal statistics and plans. A GHG reduction factor is extracted from existing studies of the effects of conversion to timber. This factor is used to estimate the GHG saving potentials of different scenarios for timber use.Main results:The forecast of building numbers, categories, sizes and location is a useful tool when discussing environmental, urban, industrial and architectural strategies.Housing in 2–8 stories, not high-rise buildings, represents the biggest potential for increased use of timber in Norway.Scientific consensus is not established regarding timber buildings and emissions. Especially the effects of carbon storage in long-lived products and use of residues for biofuel substitutes fossil fuel are still debated. To convey an order of magnitude, the different emission-saving effects are separated.The estimates of GHG mitigation indicate that conversion to use of timber may have significant effects, but measures in the transport sector are more important for reaching the ambitious emission targets in Oslo and Akershus counties.To be robust, the argument for timber buildings must include the perspective of a green industrial shift based on renewable resources and innovative technology, design and architecture.The vicinity of Norway's biggest and most rapidly growing market for timber buildings and the country's largest forests and timber-based industries represents a unique opportunity for sustainable urban and regional development.
Buildings are responsible for 37 % of global Greenhouse Gas (GHG) emissions. Subsequently, stakeholders in this sector have introduced different strategies to reduce the environmental impact of ...buildings. One strategy focuses on increasing the use of wood in buildings as a low-impact material with the potential to act as a carbon sink. Although research shows a tendency towards lower GHG emissions from wood structures compared to conventional constructions, the existing literature is typically challenged by methodological inconsistencies and only assesses a limited number of building projects at a time. As a result, uncertainties are introduced about comparisons between them, how their background and modeling assumptions may vary, as well as the integrity of the assessed solutions. Hence, this study analyses 45 cases of buildings applying the same methodology to enable a comprehensive understanding of the environmental performance of wooden buildings, identifying common trends, challenges, and best practices. This study finds that the embodied impacts contribute highly to the environmental impact and thus remain essential to consider. However, there is a very weak correlation between the quantities of wood used in the buildings and the environmental impact for wooden buildings, but a strong correlation between the quantities of insulation, plastics, composites, and POCP, ODP, ODP and EP, respectively. Therefore, the use of these materials should be optimized to further reduce the environmental impact of wood buildings.
•Embodied impact contributes highly to the impact of wooden buildings.•The quantity of wood correlates weakly with the environmental impact of buildings.•The quantity of insulation correlates with the impact on POCP.•The quantity of plastics correlates with the impact on ODP.•The quantity of composite correlates with the impact on ODP and EP.
In the move towards sustainable construction, timber and wood-based products are becoming increasingly important structural materials. The introduction of mass timber products with excellent load ...carrying characteristics allows timber to be used in larger, more complex structures. Cross-laminated timber (CLT) panel products have developed to the stage where they can be considered as economic and more sustainable alternatives to traditional materials. In this paper, the characteristics and design of CLT structures are described. Recent developments in mid- and high-rise CLT construction are reviewed and future opportunities identified. Current and future research needs are highlighted.
Currently, there is limited knowledge of the dynamic response of taller glue laminated (glulam) timber buildings due to ambient vibrations. Based on previous studies, glulam frame connections, as ...well as non-structural elements (external timber walls and internal plasterboard partitions) can have a significant impact on the global stiffness properties, and there is a lack of knowledge in modeling and investigation of their impact on the serviceability level building dynamics. In this paper, a numerical modeling approach with the use of “connection-zones” suitable for analyzing the taller glulam timber frame buildings serviceability level response is presented. The “connection-zones” are generalized beam and shell elements, whose geometry and properties depend on the structural elements that are being connected. By introducing “connection-zones”, the stiffness in the connections can be estimated as modified stiffness with respect to the connected structural elements. This approach allows for the assessment of the impact of both glulam connection stiffness and non-structural element stiffness on the dynamic building response due to service loading. The results of ambient vibration measurements of an 18-storey glulam timber frame building, currently the tallest timber building in the world, are reported and used for validation of the developed numerical model with “connection-zones”. Based on model updating, the stiffness values for glulam connections are presented and the impact of non-structural elements is assessed. The updating procedure showed that the axial stiffness of diagonal connections is the governing parameter, while the rotational stiffness of the beam connections does not have a considerable impact on the dynamic response of the glulam frame type of building. Based on modal updating, connections exhibit a semi-rigid behavior. The impact of non-structural elements on the mode shapes of the building is observed. The obtained values can serve as a practical reference for engineers in their prediction models of taller glulam timber frame buildings serviceability level response.
•An alternative approach to model connections in taller glulam timber frame buildings with “connection-zones” is proposed.•The impact of non-structural elements on the serviceability level response is explored.•The semi-rigid behavior in glulam timber connections has been shown and estimates of the stiffness range for these connections are provided.
In the protection of heritage buildings, computational models are an innovative technology for the implementation of effective preservation strategies. These models can manage both data obtained from ...the buildings and data from the knowledge base of professional experts. The preventive conservation of heritage buildings requires cooperative efforts, where the professional experts' opinions are paramount, to analyse multidisciplinary knowledge. In this respect, the incorporation of new protocols, which can help decision makers prioritize interventions and avoid restoration actions that are unnecessarily invasive or might cause irreparable loss of the properties, is urgently needed. The aim of this study is to establish a new approach concerning a digital management system that is based on artificial intelligence (fuzzy logic). Application of the model reveals that the sample (42 buildings) was classified into two vulnerability conditions: (i) medium-level affections and (ii) high-level vulnerability affections. The results obtained in this study will be useful to stakeholders who are responsible for the maintenance of heritage buildings, since this methodology allows reducing their probability of failure. This new digital management tool will help in the establishment of possible mitigation strategies that are focused on preventive future maintenance programmes of a set of heritage buildings in South Chile.
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