Timber-concrete hybrid buildings are an innovative solution to increase the amount of timber materials used in modern buildings. This study presents a dynamic evaluation of a nine-storey ...timber-concrete hybrid residential building during construction. The building has an irregular shape and consists of three to seven storeys of cross-laminated timber (CLT) on top of two storeys of concrete. In order to study the influence of non-structural elements and a heavily increased slab load in construction, ambient vibration tests were conducted seven times during the 13-month construction period. The results show a clear decrease in the natural frequencies of the building as the building gets higher and more elements are installed. However, a slight increase in the natural frequency was observed following the installation of the non-structural walls in the final construction stage. A corresponding finite element analysis is presented for each test, providing additional insights into the parameters typically used in the structural design process. The study demonstrates the importance of properly selecting reduction factors for CLT elements in a dynamic finite element analysis. It also shows the importance of considering non-structural walls, both regarding weight and stiffness, even in buildings where the number of non-structural walls is relatively small compared to structural walls.
•Modal properties of an irregularly shaped nine-storey timber-concrete hybrid building are presented.•AVTs were performed during construction, quantifying the influence of non-structural elements on the natural frequencies.•The in-plane shear stiffness of CLT walls significantly influences the dynamic response.
This paper explores the seismic behavior of the corner Dou-Gong (DG) bracket in ancient Chinese timber buildings. A full-scaled DG was tested by the pseudo-static test to study the failure mode, ...hysteretic characteristic, stiffness and strength degradation, energy dissipation and deformation capacity of the entire DG as well as the displacement of the DG components. A numerical model verified by the test was established to analyze the stress distribution of the DG and components. Parameter analysis of loading direction, wood grain direction, vertical load, and friction coefficient was also conducted. Results indicate that the positive bearing capacity, stiffness, and deformation capacity of the DG are inferior to the negative, whereas the energy dissipation capacity is excellent. The component's rotation displacement in the overhanging and oblique 45° direction rises with the loading process. The higher the component, the larger the rotation displacement, but the component's sliding displacement does not follow this law. From top to bottom of the DG, the proportion of the component's rotation displacement and sliding displacement decreases and increases respectively. The larger amount of the corner DG components makes its seismic behavior better than the Pingshenke DG. The DG exhibits its maximum positive load in the width direction and the minimum negative load in the oblique 45° direction. The grain direction of Da-Dou and Pingban-Fang can affect the bearing capacity of the DG. Increasing vertical load and friction coefficient enhances the bearing capacity of the DG.
•The corner Dou-Gong's positive seismic behavior is inferior to the negative.•The higher the upper components, the larger the component's rotation displacement.•From top to bottom of component, proportion of rotation displacement decreases.•Loading direction and wood grain direction affect Dou-Gong's bearing capacity.
The accurate characterization of environmental effects, especially temperature and humidity, on historical timber buildings is essential for the timely detection of deterioration and structural ...performance damage. This research aims to effectively exclude environmental impacts in future structural state assessments by constructing an integrated model based on combining the Prophet and extreme gradient boosting (XGBoost) methods. This hybrid model integrates the two single algorithms based on their specialties. Prophet is applied to time series analysis with the addition of humidity effects to characterize their impact on series periodicity, and XGBoost based on improved Bayesian optimization (BayesOpt) is used to describe the effects of ambient temperature and humidity on the structural responses. The hybrid model is constructed by a new optimized weighting method. The performance of the proposed model is compared with that of single models, singular spectrum analysis and polynomial regression (SSA-PR) model and two traditional weighting-based hybrid models on data collected from the structural health monitoring system of the Feiyun Wood Pavilion (FWP). The results show that the inclusion of humidity effects enables the model to more accurately characterize the relationships between environmental factors and strain, and the predictive performance of the proposed hybrid model is better than that of other models.
•Modal properties of hybrid timber-concrete building were experimentally obtained.•Masonry cladding and foundation are important when modelling dynamic properties.•CLT wall shear stiffness ...underestimated when non-structural elements are neglected.
Serviceability of tall timber and hybrid timber buildings under wind-induced vibrations has become their leading design criterion. Accurate finite element models for predicting their modal properties are crucial for designing buildings that satisfy the current serviceability criteria. It is a challenge for structural engineers to decide what to include in the structural modelling. This is because elements that are typically considered non-structural (partition walls, plasterboards, screed, façade, etc.) have been shown to act structurally and can significantly influence the modal properties of timber buildings.
This paper discusses the importance of including certain entities in finite element models of timber and hybrid timber buildings. A case study of a 5-storey hybrid timber-concrete building with masonry cladding is presented. Full-scale in-situ dynamic tests were performed on the building, using forced vibration testing with a shaker. Frequency-response-function-based modal identification resulted in 3 modes of vibration, identifying natural frequencies, mode shapes and damping ratios. A detailed finite element model was developed that estimated the measured natural frequencies with an error of slightly more than 11%.
With an extensive sensitivity analysis was found that modelling of the foundation, the effect of the adjacent abutting building in contact, and the masonry cladding was needed. After model updating, it was found that the shear stiffness of CLT walls was initially underestimated, concluding that non-structural elements such as plasterboards and partition walls might influence the dynamic properties of this hybrid timber-concrete building.
Wood is one of the most commonly-used and sustainable construction materials, but it is flammable in nature. Pre-charring is an ancient approach used to protect wooden construction materials against ...biochemical impacts, but its effectiveness in improving fire performance is still poorly understood. This work proposes a novel method to generate engineered wood with a uniform and robust surface char layer through slow pyrolysis under low thermal irradiation of 20 kW/m2. We found that the flammability of the pre-charred wood can be significantly reduced under higher irradiations up to 50 kW/m2 by increasing the ignition time by up to seven-fold and doubling the ignition temperature to about 670 °C. For the tested wood species (Merbau), we quantify a minimum char-layer thickness of 6 ± 1 mm to achieve effective fire retardancy. The fire hazards of pre-charred wood are also mitigated significantly, where observed flames become weaker, thinner, and bluer than that of the virgin wood. The peak heat release rate of burning pre-charred wood is reduced by over 50%, helping maintain the fire resilience of timber structures. This work quantifies the fire performance of pre-charred wood, highlighting a promising direction toward fire-safe timber construction materials.
•Novel engineered woods (Merbau) with robust pre-charred layers are developed.•Minimum char-layer thickness to achieve effective fire retardancy is 6 ± 1 mm.•Thermal inertia (fire-retardant performance) is extraordinarily improved.•Ignition delay time, ignition temperature and ignition heat flux all increase.•Fire hazards of the pre-charred wood are reduced significantly.
Mass timber (MT), a group of large engineered structural wooden panels such as cross-laminated timber (CLT), glue-laminated timber (Glulam), laminated veneer lumber (LVL), etc., is becoming ...increasingly popular due to sustainable construction. Despite the numerous benefits of MT-based buildings, such as low-carbon emission, short construction time, and cost-effectiveness, the concerns regarding the durability of MT may limit their market acceptance. In this review, we discuss the advantages and opportunities of applying MT in tall buildings, as well as the durability issues associated with MT application. We examine the traditional wood protection techniques including, preservative treatment, thermal and chemical modification, and discuss the potential of applying these techniques for MT protection. We survey the recent studies on MT durability evaluation, as well as the recent progress in MT structure protection through a moisture control strategy. Finally, we highlight the MT protection strategies through the preservative, thermal, and chemical treatment approaches, review the effects of these treatment methods on the properties of MT such as wettability, glue penetration, bonding strength, etc., and discuss the future of the field.
•Numerous opportunities that exist for mass timber in construction were given.•The implementation of current wood protection protocols to mass timber was explored.•The pros and cons of mass timber protection were discussed.•Further recommendations on evaluating the durability of mass timber were given.•The impacts of treatment on the properties of MT were discussed.
This paper presents a literature overview of the acoustic studies dedicated to lightweight wooden constructions. The reviewed articles contain prediction models, laboratory and field measurements, ...finite element or computational investigations as well as subjective survey describing the vibro-acoustic behaviour of a large range of wooden structures. The review analyses different type of timber constructions and investigates the acoustic research methodologies highlighting the following aspects: airborne sound insulation, impact noise reduction, flanking transmissions, human perceptions and pros and cons of the presented methods. Furthermore, an in-depth analysis of impact noise of bare floors focuses on how impact sound reduction could not be as efficient as in heavyweight constructions; the comparison between the different approaches on prediction of airborne sound insulation of multilayer timber partitions compared to traditional heavy building materials is shown. Finally a subjective method survey is provided, underlining the weakest point of timber buildings: low frequency sound insulation.
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