Cross-laminated Timber Structures Research Articles

Evaluation of different acoustic insulation methods in CLT structures

This study explores the efficacy of various structural noise insulation systems implemented in the construction of pilot houses made from Cross-Laminated Timber (CLT). Focusing on both vertical and lateral transmission, the research aims to evaluate the performance of different insulation methods in mitigating structural noise within these innovative wooden structures. The investigation involves a comprehensive testing regimen to assess the impact of insulation systems on noise reduction, considering both practical applications and theoretical considerations. The findings of this study contribute valuable insights into enhancing the acoustic performance of CLT pilot houses, thereby informing best practices for noise insulation in wooden construction systems.

COMPARATIVE ANALYSIS OF CALCULATION METHODS OF CLT STRUCTURES

One of the important tasks of modern construction is the search for new constructive solutions and the introduction of new construction technologies. Cross-Laminated Timber (CLT) technology is a new material for Ukraine that has proven itself in Europe and America as effective and environmentally friendly with many advantages. Since CLT panels are not widely distributed, studied and do not contain references in the normative literature in Ukraine, the study of these structures is extremely relevant. This paper presents a comparative analysis of the CLT calculation methods of panels: using the RFEM 6 and LIRA-FEM software and analytical calculation. The research concerns three types of panels: three-layer, five-layer, and seven-layer under the action of a load of 1.5 and 5.0 kN/m2. The main parameter under consideration is the vertical deflection of the panels. The results of all calculations are collected in one table, where you can analyze the discrepancy between different methods of calculating the CLT structures.

An innovative energy-dissipation angle bracket for CLT structures: Experimental tests and numerical analysis

The connection system controls the behavior of the Cross-laminated timber (CLT) structures under horizontal loads. This paper introduced an innovative energy-dissipation angle bracket for CLT structures, which takes advantage of the soft-steel bracket and high-damping rubber to provide superior ductility and energy-dissipating capacity. Experimental tests under monotonic and reversed cyclic loading were performed to investigate the failure mechanism and mechanical properties of this energy-dissipation connector. After validating the detailed finite element models based on the test results, numerical parametric analysis was conducted to evaluate the influence of several parameters. The results show that the energy-dissipation angle bracket connector mainly exhibits three failure modes, including the rupture of dissipative ribs, local bearing failure of the base, and the debonding of the internal rubber. The ribs’ rupture is the dominant failure mode, especially under cyclic loading, after which the connector can still work integrally because of the rubber that is tightly bonded to the steel skeleton. All the tested connectors show high ductility and great energy-dissipating capacity, as indicated by the ductility larger than 9.5 and the equivalent viscous damping ratio within 9 %− 26 %. According to the numerical parametric analysis, the load-carrying capacity of the energy-dissipation angle bracket is positively correlated with the steel skeleton’s thickness and ultimate strength, and the adoption of the washer, while the rubber’s height has little impact on the load-carrying capacity. The outcomes of this study provide valuable references for subsequent improvement and potential applications of the innovative angle bracket for CLT structures.

Full-scale shaking table tests of cross-laminated timber structures adopting dissipative angle brackets and hold-downs with soft-steel and rubber

Cross-laminated timber (CLT) has recently attracted significant interest in building timber or hybrid structures owing to the rapidly growing demand for low-carbon construction materials with excellent mechanical properties. To investigate the seismic performance of CLT structures adopting novel dissipative angle brackets and hold-downs with soft-steel and rubber (i.e., SRD-ABs and SRD-HDs), a series of shaking table tests were performed on two full-scale specimens, i.e., a benchmark specimen (Specimen Ⅰ) and a specimen with a multi-doorway at the ground (Specimen Ⅱ). Several representative ground motions, including the Turkey wave, El Centro wave, Wenchuan wave, and Shanghai artificial wave, were selected as excitations, whose peak acceleration increased gradually from 0.035 g to 0.80 g. The damage patterns of the structures were revealed, and the dynamic characteristics and responses were obtained and analyzed. The results show that the fundamental frequencies of Specimen Ⅰ and Specimen Ⅱ were 4.125 Hz and 3.625 Hz, respectively. The mode shapes of each specimen remained similar before tests with peak ground acceleration (PGA) of 0.51 g, with only a slight decrease of approximately 5 % in the fundamental frequency, indicating that the specimens only suffered minor damage because of the great energy-dissipating capacity of the SRD-ABs and SRD-HDs. After experiencing tests with PGA of 0.80 g, the specimen exhibited a maximum inter-story drift of 1/60 with a structural damping ratio of 13 %, and the damage was mainly exhibited at the SRD-ABs and SRD-HDs, which realized the performance objective of replaceability of dissipative connections and repairability of structures under the 9-degree rare earthquakes. Furthermore, non-linear numerical models were developed to duplicate the dynamic characteristics and responses of the test specimen, and the analytical results from the models show satisfactory agreement with the test results. Overall, the outcomes of this paper can provide valuable references for future research and applications of CLT structures with the SRD-ABs and SRD-HDs.

Research on Lateral Resistance Performance of Prestressed Cross-Laminated Timber-Concrete Composite Structures under Reciprocating Loads.

Cross-Laminated Timber (CLT) and concrete composite structures represent an architectural system that integrates the strengths of both materials. In this innovative configuration, the CLT and concrete collaborate synergistically, harnessing their individual merits to achieve enhanced structural performance and functionality. Specifically, the CLT offers a lightweight design, superior bending resistance, and immense engineering plasticity, while concrete boasts exceptional compressive strength and durability. This study investigates the mechanical performance of CLT-concrete composite structures through quasi-static reciprocating loading tests in three full-scale CLT shear wall samples. Designed with varying initial prestressing forces and dimensions of the CLT panel, the prestressed CLT-concrete structures demonstrated a reduced dependence on the steel nodes, resulting in an increase in yield load, yield displacement, and maximum load-carrying capacity. Maximum capacity increased by 39.8% and 33.7% under initial prestressing forces of 23 kN and 46 kN on steel strands. Failure occurred due to localized compressive failure on prestressed steel strands and anchor plates. ABAQUS finite element analysis established three refined models, revealing that the increased initial prestressing force moderately enhanced stiffness but reduced ductility under similar cross-sectional dimensions. Furthermore, under consistent CLT material, dimensions, prestressing force, and loading conditions, prestressed CLT-concrete structures exhibited a higher maximum load-bearing capacity than prestressed CLT-steel composite structures. This study proposes structural design recommendations based on experimental and simulation results, incorporating specific assumptions.

Impact of sound-insulated joints in the dynamic behavior of Cross-Laminated Timber structures

Cross-Laminated Timber (CLT) has gained an increasing success and widespread diffusion among wood products. Due to the novelty of the components and the dry-assembling techniques, certain aspects of its behavior and performance remain unexplored; among these, the use of sound-insulated joints and brackets, along with their possible drawbacks on mechanical performance.In this paper the authors discuss the results of dynamic identification (ID) tests carried out on twin full-size CLT mockups (two-story), one of which was furnished with sound-insulation details based on an elastomeric interlayer. Ambient (white noise and random excitations) and forced vibration (mass shaker) tests were carried out to identify modal parameters.The paper mainly aims at: i) assessing potential differences in the overall dynamic behavior of the two mockups, likely due to the introduction of acoustic insulation, ii) detecting possible drawbacks of insulation layers on mechanical performances, iii) increasing the knowledge about dynamics of CLT structures.The results of Operational Modal Analysis (OMA) are presented and the variations in the dynamics between the mockups are discussed. The construction of finite element (FE) models and their calibration – with joint properties variations – are then presented. The outcomes revealed a drop of modal frequencies values (at least 20 %) upon the introduction of elastomeric insulation, whilst no significant alteration was observed in the mode shapes. Model updating based on the FE models demonstrated that the dynamic response and the frequency variations were mostly associated with wall-to-wall and wall-to-diaphragms joints, and hold-down connections.

CONCEPTS FOR TIMBER-SPECIFIC MEP INSTALLATIONS AND SEALINGS IN BATHROOMS OF MULTI-STORY RESIDENTIAL BUILDINGS

The European market for cross-laminated timber (CLT) is rapidly growing in the field of multi-story residential buildings. However, water leaks repeatedly lead to severe moisture damage in timber buildings. Undetected moisture damage may result in biological degradation of the CLT structure, is difficult to repair, and incurs high costs. Currently, there is a lack of awareness of the fact that timber buildings require different mechanical, electrical and plumbing (MEP) installation methods than buildings made with mineral construction materials. In addition, too little attention is given to protecting the wooden structure by applying appropriate sealing measures that actually work in practice. Lack of planning and uncoordinated construction work exacerbate this problem. Presenting 2D drawings and 3D BIM models, the paper illustrates concepts that can be used to optimally design and safely integrate MEP installations in bathrooms in multi-story residential timber buildings. A special focus is placed on a holistic view of the topics structure, pipe installation, sealing, and fire protection. The concepts presented are based on an analysis and classification of over 1100 bathroom layouts. Therefore, they are applicable to a wide range of bathrooms in practice. The presented results were developed in the research project CLT_Plumbing_Design. They contribute to the development of standardized, timber-specific solutions for pipe installation and sealing in bathrooms, and can help reduce moisture damage in timber construction. In addition, these concepts form a basis for a new automated planning process in the area of bathroom planning, for which a brief outlook is given.

CONCEPTS FOR TIMBER-SPECIFIC MEP INSTALLATIONS AND SEALINGS IN BATHROOMS OF MULTI-STORY RESIDENTIAL BUILDINGS

The European market for cross-laminated timber (CLT) is rapidly growing in the field of multi-story residential buildings. However, water leaks repeatedly lead to severe moisture damage in timber buildings. Undetected moisture damage may result in biological degradation of the CLT structure, is difficult to repair, and incurs high costs. Currently, there is a lack of awareness of the fact that timber buildings require different mechanical, electrical and plumbing (MEP) installation methods than buildings made with mineral construction materials. In addition, too little attention is given to protecting the wooden structure by applying appropriate sealing measures that actually work in practice. Lack of planning and uncoordinated construction work exacerbate this problem. Presenting 2D drawings and 3D BIM models, the paper illustrates concepts that can be used to optimally design and safely integrate MEP installations in bathrooms in multi-story residential timber buildings. A special focus is placed on a holistic view of the topics structure, pipe installation, sealing, and fire protection. The concepts presented are based on an analysis and classification of over 1100 bathroom layouts. Therefore, they are applicable to a wide range of bathrooms in practice. The presented results were developed in the research project CLT_Plumbing_Design. They contribute to the development of standardized, timber-specific solutions for pipe installation and sealing in bathrooms, and can help reduce moisture damage in timber construction. In addition, these concepts form a basis for a new automated planning process in the area of bathroom planning, for which a brief outlook is given.

Numerical parametric study of cross-laminated timber diaphragms under in-plane loading

Cross-Laminated Timber (CLT) is a mass timber product that has gained recognition as a viable structural product for tall and large structures. While CLT provides several advantages, such as being eco-friendly, lightweight, and improving thermal insulation compared to other primary structural materials, its application in the horizontal diaphragms, specifically for floors and roofs, has not been thoroughly investigated. This paper presents the development of a detailed finite element (FE) model capable of simulating the response of CLT diaphragms under in-plane loading. The accuracy of the developed models was evaluated through comparison with available experimental data. Additionally, a comprehensive parametric study was conducted to examine the influence of various factors, including connection stiffness, boundary condition, panel installation pattern, and panel thickness, on the in-plane deflection of the CLT diaphragm. The research indicates that panel-to-panel connections play a more critical role in determining the stiffness of CLT structures than panel-to-beam connections. Furthermore, it was demonstrated that the deflection of CLT panels was influenced by different parameters depending on the orientation of the applied load. When the load is applied perpendicular to the panel length, panel thickness influences the diaphragm deformation. Conversely, when the load is applied parallel to the panel length, the panel-to-panel connection stiffness has a more significant effect on the deformation of the diaphragm. Findings also revealed that staggered CLT panel layouts provided more load distribution and higher capacity compared to non-staggered layouts when the load was applied perpendicular to the panel length.

Impact of Insulation Strategies of Cross-Laminated Timber Assemblies on Energy Use, Peak Demand, and Carbon Emissions

Cross-Laminated Timber (CLT) panels have many structural benefits but do not have much thermal resistance. We have developed a solution to insulate CLT structures that uses high-performance insulation panels that provide R-values up to R40/inch. The CLT panels are made of layers of wood laminates (three, five, seven or more). The solution replaces some of the wood laminates in the CLT production with the insulation panels in a staggered fashion so that the wood laminates maintain contact throughout the panel, ensuring the CLT panel’s structural integrity. The insulated CLT panels have factory-installed water-resistive barriers reducing the installation time by eliminating installing insulation and water-resistive barriers on site. Per simulations, the CLT/insulation panel achieved code-required insulation levels with commonly available insulation materials. The significance of the thermal mass of CLT/insulation hybrid building envelopes was quantified by comparing the whole building energy performance and peak demand of traditional low mass and CLT wall assemblies resulting in up to 7% reduction in peak demand for cooling in Knoxville, TN, in a multifamily building. Buildings contribute over 40 percent of carbon emissions. The proposed CLT/insulation hybrid building envelope addresses both operational and embodied carbon by having high thermal resistances due to the embedded insulation sections and eliminating the use of high embodied carbon materials such as steel and concrete. The carbon benefit is estimated.

Experimental research on lateral performance of CLT shear walls with novel dissipative angle brackets and hold-downs

Cross-laminated timber (CLT) structures offer a prospective solution to mid- and high-rise buildings. This paper reports experimental research on the lateral performance of CLT shear walls with novel dissipative angle brackets and hold-downs adopting soft-steel bracket and rubber. Quasi-static tests were performed on seven full-scale walls, comprising five walls with dissipative connections, one with in-situ replaced dissipative connections on already used CLT panels, and one with conventional metal connections, to investigate the influence of vertical load distributions, aspect ratios, and reparability. Failure modes, mechanical properties, and energy dissipation capacity were obtained and analyzed. The results show that the damage of the walls with dissipative connections primarily occurred at the connections, and these walls have excellent lateral deformation capacity, whose inter-story drift ratio can be up to 4.35%. Compared with the conventional metal connections, the walls with dissipative connections exhibit 26% higher ductility, 37.6% greater energy dissipation capacity and higher equivalent viscous damping ratios. Meanwhile, the repaired CLT shear walls maintained similar mechanical properties as the original wall, showing satisfactory reparability. Furthermore, non-linear numerical models were established to predict the walls’ lateral behavior, and the analytical hysteresis curves agree well with the test results.

Regression algorithms-driven mechanical properties prediction of angle bracket connection on cross-laminated timber structures

The construction of structures using cross-laminated timber (CLT) has grown in popularity as a result of its environmentally friendly and high-strength characteristics. The primary function of angle bracket connections is to resist the force of CLT structures under horizontal forces, which is essential to ensure the seismic resilience and ductility of CLT structures. A regression algorithms-driven method for predicting the mechanical performance of angle bracket connections is introduced in this study. As input parameters, the geometric dimensions of the angle bracket connector, the connection method of the connector with the wall and floor slabs, and the properties of the CLT panel are utilized to predict the yield load, the maximal load, the initial stiffness, and the ductility ratio of the angle bracket connection. Prediction models were developed using the collected data from 110 angle bracket experiments, and each prediction model's performance was discussed in depth. Lastly, the permutation importance and SHapley Additive exPlanations (SHAP) value analysis were used to interpret the prediction models. The results showed that the extreme gradient boosting (XGB) algorithm could accurately predict the maximum and yielding load of the angle bracket connection, with R2 reaching 0.968 and 0.939. Furthermore, in predicting the initial stiffness of the angle bracket, the XGB algorithm performed the best with an average ratio of predicted to actual values of 0.985. The results indicated that this study proposed an accurate and efficient method for angle bracket connection to predicting its mechanical properties and confirmed the trustworthiness and feasibility of the prediction models.

Moisture safety strategy for construction of CLT structures in a coastal Nordic climate

To reduce the carbon impact of new buildings, wood is seeing increased use as a structural material. Cross-laminated timber (CLT) and glue-laminated wood (glulam) elements allow the construction of multi-storey buildings. However, wood is vulnerable to moisture, especially when naked wood is exposed to weather during the construction process. This paper presents the moisture strategy employed during the construction of a four-storey CLT/glulam building in Trondheim, Norway. The building was constructed without the use of a weather-protective tent, requiring alternative protective measures. The construction of the main structure was scheduled to be as short as possible. Local protective measures were employed to protect the structure from rain and free water was removed after rain events. The project was closely supervised by the client, with particular care for moisture control. Moisture was regularly measured at 50 points throughout the building. No wooden surfaces were encapsulated until a wood moisture content below 15 weight-% was measured. The performance of the moisture strategy was evaluated using measurements of wood moisture, indoor climate, airtightness, and visual inspections. The wood moisture content quickly decreased as the building envelope was assembled, indicating that drying was well facilitated. In the first year after construction, gaps between the flooring and baseboards were observed, suggesting that the wooden elements have experienced some shrinkage. The moisture safety strategy is deemed to have been generally successful. The overall experiences were important in the development of new recommendations in the SINTEF Building Research Design Guides for CLT structures.

Development of laboratory experiments to determine critical moisture condition of CLT constructions

There is an increased interest in using Cross-laminated timber (CLT) in construction, but many buildings are erected without weather protection, which poses a risk of moisture impact if wood is exposed to precipitation during construction. The construction industry argues that there are no documented critical moisture levels for CLT and no specific test method. In the study, a laboratory test set-up was developed to study mould growth under realistic and controlled climatic conditions after exposure to distilled water and spore suspension. In the experiments, small test specimens of CLT structures were exposed to distilled water for 1 day or 1 week. During the development of the method it was found that exposed for one day and then given the opportunity for open drying did not give rise to mould growth. On the other hand, growth occurred on surfaces that could not dry immediately, for example at connection points. For specimens exposed for one week, mould growth arose regardless of whether the surfaces could dry immediately or not. The conclusions apply primarily to the climates studied. The methodology needs to be further developed, with other scenarios being studied, and calibrated against samples exposed to outdoor air, dust, dirt and rainwater.

Out-of-plane shear performance of a novel non-metallic CLT dovetail joint subjected to monotonic and cyclic loading

Timber structures have garnered increasing attention owing to their sustainability and assemblability. Particularly, engineered wood products like cross-laminated timber (CLT) coupled with digital fabrication technologies have promoted the application of traditional mortise-tenon joints in modern mass timber structures. In this paper, a novel non-metallic dovetail joint was proposed to connect the perpendicular CLT wall and lintel. A total of nine specimens were tested under monotonic and cyclic loading to investigate the out-of-plane shear behavior with different widths of the tenon head. The failure modes of the joints were presented, and the mechanical properties including stiffness, strength, ductility and energy dissipation were compared and analyzed. A simplified strength model was developed to evaluate the shear strength of the joint. The experimental results revealed that the specimens mainly failed by timber splitting and crushing under monotonic loading due to the shear force and additional bending moment. The increase in the tenon head width of the dovetail joint from 70 mm to 105 mm resulted in a significant improvement in both stiffness and strength, with enhancements of more than 42 % and 54 %, respectively. All specimens exhibited similar failure modes but more severe timber crushing under cyclic loading. Due to the damage accumulation, the stiffness and strength of the dovetail joint degraded significantly. The specimen with the tenon head width of 84 mm exhibited the highest energy dissipation and relatively low strength degradation under cyclic loading. Additionally, it is recommended to use a ratio of tenon head width to CLT panel thickness at 4/5. The proposed strength model underestimated the load-carrying capacity of the joint generally due to the neglect of the contribution of the bending moment. This study provides base guidelines for the application of dovetail joints in CLT structures.

Seismic acceleration demands in tall CLT buildings, predictive models and intensity measures

An accurate prediction of floor accelerations is crucial for estimating damage to contents and non-structural components in a building. Oversimplifying the nature of acceleration demands might result in biased estimates of building damage 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-storey 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 (Linear and Polynomial regressions) as well as machine learning algorithms (Decision trees, Random forest, K-nearest neighbour, 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, their PFA estimates obtained are compared against previous research and design codes. Finally, simplified expressions for estimating peak floor accelerations in CLT structures are provided for practical purposes.

The impacts of sustainable design practices and cross laminated timber structures on acoustic design

More projects in Australia are prioritizing sustainable design practices throughout their building life cycle. Environmental Sustainable Design (ESD) rating tools such as WELL, Green Star, and the Living Building Challenge (LBC) have existed for a decade or more, with some receiving wide adoption in Australia. These rating tools require the assessment of the ingredients, volatile organic compounds (VOCs), and embodied carbon of the materials specified on the project. In addition, cross-laminated timber (CLT) buildings are becoming a more attractive development option due to lower embodied carbon, a reduction in the structural requirements of the foundations, and an increased speed of construction. These sustainable practices are reviewed using a recent project example that combines these recent developments in sustainability: a commercial office fitout in a hybrid steel and cross-laminated timber structure that is targeting WELL Platinum and the Living Building Challenge. The challenges of specifying materials to meet sustainability targets, potential gaps in available products, and the acoustic design challenges of achieving high levels of sound insulation in cross-laminated timber structures are discussed. With a better understanding of sustainable design practices, acoustic designers can improve sustainability outcomes on all projects.

A comparative cradle-to-grave life cycle approach for addressing construction design choices: An applicative case study for a residential tower in Aalborg, Denmark

Energy demand reduction targets and sustainable design paradigms are fueling the search for more and more effective design solutions in the building sector, and new technologies and construction systems are being presented. However, each design solution has its own consequences for the environmental impact of the building. The use of Building Information Modelling (BIM) and Life Cycle Assessment (LCA) can be profitably adopted for supporting the decision-making process. This paper reports a comparative methodology developed to analyse the impacts of alternative structural solutions for timber-based high-rise structures. Embodied, operational, and end-of-life environmental impacts based on two structural frame types, a reinforced concrete (RC) structure and cross-laminated timber (CLT) are explored. Two main inputs are used for performing a comprehensive cradle-to-grave LCA for the whole building: the bill of quantities from a Revit BIM model and the energy demand from DesignStudio. Then, an LCA is performed using the One Click LCA tool for a service life of 50 years and 12 impact categories. The environmental impacts of building materials are based on Environmental Product Declarations (EPDs) directly embedded in the tool. The method is then applied to a case study in Aalborg, Denmark. Results indicate that the total emissions for the considered case study are 9.6 kg- CO2 eq./m2/y for the CLT structure against 10.8 kg- CO2 eq./m2/y for the RC structure. The production stage of building materials, including building systems and installations, accounts for around 55% of the total emissions, while energy use (B6 phase) during the in-use stage of the building recorded a lower environmental impact (45%). The outcomes confirm the opportunity to base the discussion on alternative design options on more objective and data-based elements to support the different positions which already involve a wide range of architectural, functional and financial criteria. This is of great relevance in achieving balanced and informed decisions which do not simply follow green-labelled ideas but are grounded on evidence-based considerations.

Seismic performance evaluation of self-centering balloon-framed CLT building

Balloon-framed cross-laminated timber (CLT) construction has a number of advantages when compared to platform-type construction; however, many international standards only include provisions for the latter as there is little research reported on the seismic performance of the former. In this paper, a seismic fragility assessment of a 4-storey balloon-framed CLT building in Vancouver, Canada, is presented. This structure is the first in North America that adopts a self-centering friction-based technology for the hold-downs (HDs). The seismic performance of the building was assessed by performing incremental dynamic analysis (IDA) on a three-dimensional finite element model using Cascadia Subduction Zone ground motions, and compared to a second building model with conventional dowel-type HDs. The analyses at the design intensity level showed that the self-centering building had an average maximum inter-story drift ratio of 0.67%, well below the 2.5% drift limit specified in the National Building Code of Canada. Based on the IDA and taking into account uncertainties, the building had a collapse margin ratio of 2.96 and a 5.2% probability of collapse at the design level. Compared to the conventional HDs, the friction-based HDs did not improve the building’s collapse capacity, but reduced the building drift by more than 20% at lower damage states, demonstrating the effectiveness of designing balloon-framed CLT structures with a resilient self-centering HDs in high seismic zones.

Seismic control of cross laminated timber (CLT) structure with shape memory alloy-based semi-active tuned mass damper (SMA-STMD)

Cross laminated timber (CLT) is becoming increasingly popular for constructing multiple-story buildings due to its alignment with Sustainable Development Goals of United Nations. However, such structures can be susceptible to excessive vibrations during earthquakes. While tuned mass dampers (TMDs) can be used to control these vibrations in CLT structures, their effectiveness can be reduced due to the lightweight nature of CLT and changes in its structural mass or deterioration of the wood. To address this issue, this paper proposes the use of shape memory alloy-based semi-active tuned mass dampers (SMA-STMDs) for controlling vibrations in CLT structures. This study includes the design and experimental testing of a full-scale, novel spring-pendulum combined SMA-STMD system, which utilises the mechanical properties of SMAs that change with temperature to achieve semi-active control. Finite element method simulations demonstrate that the proposed SMA-STMD system can effectively reduce structural seismic vibrations in CLT structure. By adjusting the SMA temperature, the SMA-STMD system can effectively address the issue of TMD system off-tuning caused by changes in the CLT structural properties. Overall, the proposed SMA-STMD system offers a promising solution for seismic control in CLT structures and has the potential to promote the development of CLT structures.