Historic Timber Research Articles

Seismic Behaviors of Historic Timber Buildings Considering the Looseness of Mortise-Tenon Connections

ABSTRACT Due to the effects of the long-term loads, earthquakes, as well as aging and decay of the wood, existing historic timber buildings (HTBs) are inevitably damaged, especially by mortise–tenon loosening. Therefore, this paper aimed to investigate the seismic behaviors of HTBs considering the looseness of mortise–tenon connections. Shaking table tests were conducted on a 1/3.52 scale model of an intact HTB made by the Engineering Code of the Qing Dynasty to simulate seismic loads and study the seismic response of HTBs. The deformation characteristics, failure modes, and dynamic response of the test model were all studied. Furthermore, the modal and dynamic response analyses of all finite element models (FEMs) were used to investigate the influence of looseness on seismic behaviors of HTBs. The results show that with a larger damaged degree than 13.3%, the inter-story drift ratio (IDR) θ of the damaged model with looseness mortise–tenon connections resulted from earthquakes, is more than the IDR limit of 1/30 under an 8-degree rare earthquake, indicating that the HTBs must be strengthened and retrofitted immediately.

Timber harvesting was the most important factor driving changes in vegetation composition, as compared to climate and fire regime shifts, in the mixedwood temperate forests of Temiscamingue since AD 1830

ContextThe vegetation composition of northeastern North American forests has significantly changed since pre-settlement times, with a marked reduction in conifer-dominated stands, taxonomic and functional diversity. These changes have been attributed to fire regime shifts, logging, and climate change.MethodsIn this study, we disentangled the individual effects of these drivers on the forest composition in southwestern Quebec from 1830 to 2000 by conducting retrospective modelling using the LANDIS-II forest landscape model. The model was run based on pre-settlement forest composition and fire history reconstructions, historical timber harvest records, and climate reanalysis data. We compared counterfactual scenarios excluding individual factors to a baseline historical scenario.Results and ConclusionsOur results indicated that timber harvesting had the greatest impact on forest dynamics over the past centuries. In the absence of timber harvesting, pre-settlement species abundances were largely maintained, preserving key functional traits like fire and shade tolerance that contribute to ecosystem resilience. Increased fire activity during the settlement period contributed to the increase of early-successional aspen (Populus tremuloides), but timber harvesting played the dominant role. Fire exclusion had no influence on vegetation composition, suggesting mesophication unfolds over longer timescales than those captured in this study. Climate change, characterized by modest increases in temperature and precipitation, had a minor effect on vegetation shifts, as increased precipitation might have mitigated the adverse effects of rising temperatures. However, future climate change is projected to become a more significant driver of forest composition. These findings underscore the importance of forest restoration and continued research on past forest dynamics to better understand current and future changes.

Bending Properties and Lateral Resistance of Historic Timber Foundation Piles in Amsterdam, Netherlands

Bending Properties and Lateral Resistance of Historic Timber Foundation Piles in Amsterdam, Netherlands

Digital Twins in Structural Health Assessment and Monitoring: Applications in Historical Timber Buildings

ABSTRACT This paper explores the application of Digital Twins (DTs) for supporting the structural health monitoring (SHM) of timber buildings, with a particular emphasis on historical timber structures. It reviews technologies and methods for DT creation, examining how geospatial data and Building Information Modeling (BIM) serves as foundational elements in developing digital twins. The paper discusses integrating these elements with various data and models to enhance SHM tasks, detailing actionable DT approaches for documenting, analyzing, simulating and predicting structural behavior. The study highlights that while high-fidelity geometric models are well developed, their application for advanced SHM tasks remains limited. Integration of sensor data into BIM frameworks is promising but still faces challenges such as limited automation and difficulties in handling real-time and long-term data. Additionally, the paper notes that the implementation of DTs for the simulation of the effects of hygrothermal phenomena on the long-term behavior and durability of timber structures is underexplored. Multi-dimensional BIM models and machine and deep learning techniques in data-driven, physics-based models are promising approaches for timber cultural heritage management and beyond.

Experimental and numerical study on fire development process and fire risk assessment of historic timber lounge bridges

Historic timber lounge bridges are precious architectural heritages. But they are sensitive to fire. In order to obtain an adequate understanding of the fire vulnerability of historical timber lounge bridges for their better conservation, this paper proposes a framework based on experiment and computational fluid dynamics (CFD) analysis. Dengyun Bridge, a typical timber lounge bridge with cantilever beams, was chosen to carry out study on the fire development process and fire risk assessment. Firstly, the structural form and fire loads of the bridge were obtained by conducting on-site survey, and then a complex pyrolysis model of ancient wood was established in the Fire Dynamic Simulator (FDS) according to the pyrolysis characteristic of the ancient wood replaced from the bridge during its renovation. Secondly, the fire development process in Dengyun Bridge was simulated and four crucial fire events were defined. Finally, the comprehensive fire risk index for the Dengyun Bridge under those fire events was calculated by applying the Analytic hierarchy process (AHP) and Entropy method, and some mitigation and prevention strategies were discussed accordingly. The obtained results indicated that the flashover point was a boundary of fire development. After the flashover, the comprehensive fire risk index increased and reached its peak value rapidly. In the 1084 s (peak heat release rate), the comprehensive fire risk index was about 1.7 times of that in 847 s (flashover point). Mitigation strategies, such as the flame-retardant treatment and water-mist extinguishing system, were proved to be effective to retard the developed fire. The results of this study can provide a scientific basis for fire risk assessment and conservation of inherited timber lounge bridges.

Combination of LiDAR detection and green integral method for calculating irregular cross-section geometric properties of deteriorated components in timber historic buildings

Timber components in historic buildings are susceptible to deterioration due to the complex external environment. The loss of material in these components and changes in their cross-section geometry significantly impact the stability and load-bearing capacity of historic buildings. A portable LiDAR device is utilized to acquire the cross-section geometry of the deteriorated components. The irregular cross-section profiles are extracted using point cloud slicing and the Alpha-Shape algorithm. Geometric characteristics such as cross-section area, moment of inertia, and moment of resistance are calculated using Green's integral method. The performance of this method is evaluated by measuring eight groups of deteriorated components with different cross-section characteristics and comparing it with five traditional methods. The results demonstrate that the proposed method improves the calculation accuracy by 1%–21% relative to traditional methods, thereby enhancing reliability by 9%–54%. Additionally, it reduces manual calculation workload and human error, while promoting calculation efficiency. The method exhibits excellent applicability and high efficiency, with an error below 3% when compared to the true value. This method proves valuable in evaluating the extent of deterioration in historic timber components and provides essential data for preventive conservation and restoration of historic timber buildings.

Precision detection and identification method for apparent damage in timber components of historic buildings based on portable LiDAR equipment

For the purpose of preservation and restoration of historic timber buildings, it is critical that damage to timber components must be detected and identified accurately since proper detection and identification lay the foundation for scientific utilization and preservation of cultural heritage. Portable smart devices with integrated LiDAR sensor technology have significantly advanced, enabling them to be major pedestals for damage detection. An iPhone Pro based technique is therefore suggested for the precise detection and diagnosis of apparent damage to the timber components. The study consists of three major procedures. First, an apparent data collection of the timber components was conducted. A high-resolution triangular mesh model was utilized for precision detection and identification. Point cloud and texture data were the main constituents of this data collection. Second, a technique for image processing and apparent damage analysis was proposed for crack detection in historic timber buildings. This approach can be used to identify, recognize,and assess damage to timber components such as cracks, rotting, and knots. Finally, actual measurements of the timber components in Datong, Shanxi Province, at the Great Temple Corner, proved the effectiveness of the iPhone 12 Pro as a substitute approach to the conventional inspection equipment. The findings indicate that the iPhone 12 Pro, which has a built-in LiDAR sensor, performs exceptionally well in terms of effectiveness, accuracy, and graphical interpretation when identifying apparent damage to historic timber components. Moreover, it has the potential to substitute traditional measurement, 3D scanning, and other detection and identification techniques. Even though damage detection and identification of historical timber buildings has reached a mature stage in terms of portable, refined, and digital transformation, such technique can serve as a compatible addition as a safe, affordable, and paradigm shifting technical solution for detection and identification of historic building components.

A dendroarchaeological tree-ring dataset of Abies alba Mill. from historic buildings in the French Pyrenees

Key messageThis article presents ring width chronologies derived from samples extracted from historical timber buildings in the French central Pyrenees. Two chronologies for fir (Abies alba Mill.) were dated for two periods: 1446–1655 and 1679–1952 AD. These chronologies are suitable for dendroarchaeological and paleoenvironmental studies, or for reconstructing past climates. Dataset access is at https://doi.org/10.48579/PRO/KH6HPC and associated metadata at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/edba546e-3769-4f06-959b-f0d8db7fbcdb.

Charring of and Chemical Changes in Historical Wood under Thermal Loading

Research in historical timber assessment is hindered by the limited availability of samples, yet understanding the fire resistance of historic wood is crucial for preservation efforts. There is an opinion that historic wood behaves similarly to contemporary wood in terms of fire resistance. The aim of this paper is to observe the rate of charring of historical pine wood during the experiment, the color changes in the sample that occurred due to thermal loading, and the changes in the chemical composition of pine wood. Test samples made from historic pine wood were loaded with a 50 kW∙m−2 radiation panel for 60 min. The charring process was faster at the beginning of the charred layer formation. The charring rate at the beginning of the test at a depth of 10 mm from the exposed side reached values from 1.28 mm∙min−1 to 3.16 mm∙min−1. At a depth of 30 mm from the exposed side, the individual charring rates approached a value of 1 mm∙min−1 (0.99 mm∙min−1 to 1.08 mm∙min−1). Observations during medium-scale testing revealed distinct layers forming on the exposed side: a charred layer, charring base, pyrolysis layer, and intact wood. The chemical composition of the wood changed under the influence of the thermal load. The relative contents of extractives and holocellulose decreased with the increasing temperature while the lignin content increased. The highest value of combustion heat was measured in the charred layer of the sample. Correlation analysis demonstrated a negative relationship between the combustion heat and holocellulose, while a positive correlation was found with the lignin content. Chemical changes were also monitored using the FTIR method. These findings provide valuable insights into the behavior of historic pine wood under thermal loading, which is essential for understanding and preserving historical structures.

Numerical simulation and safety assessment of fires in historic timber structures based on fire load investigation

Historic timber structures face substantial fire loads and complex fire risks. Subsequent renovations and utilization may influence their fire safety performance. Therefore, accurately predicting indoor fire development in historic buildings and assessing their fire safety performance is crucial. Numerical fire simulation is currently at the forefront of analyzing and assessing fire risks in historic buildings. However, there is a shortage of globally accessible historic building fire data. This paper proposes a method to determine fire scenarios, peak heat release rates, and development curves of indoor fires in wooden historic buildings through a fire load investigation. Using the Guangzhou ancestral hall as an example, PyroSim fire dynamics simulation software is employed to calculate fire development and assess the available safe evacuation time. The simulation results are subsequently input into the Pathfinder evacuation simulation software to ascertain the required safe evacuation time for indoor occupants. A comparative assessment is conducted to evaluate the fire safety performance before and after the renovation of historic buildings. The research findings indicate that installing closed glass curtain walls in the courtyards of ancestral hall buildings in Guangzhou accelerates the infiltration of smoke during fires, leading to rapid fire spread and long-distance ignition, significantly reducing the time available for safe evacuation. Therefore, when renovating and utilizing the ancestral hall buildings in Guangzhou, the installation of ventilation and smoke extraction systems should be prioritized to slow down fire development. Additionally, controlling the number of indoor occupants is an effective management measure to mitigate fire damage in historic buildings.

An Analysis of the Fire Performance of Small-Scale Canadian Heritage Hardwood and Softwood

A common consideration in the rehabilitation of historic timber structures is addressing the concerns for fire safety. Heritage structures can have softwoods but depending on the time they were built they may also have hardwoods present. Currently, there is a lack of knowledge on the char rate of heritage hardwood and softwood. This study presents initial findings into the charring of these historic materials as they would be encountered in practice through samples taken from pre-existing aged timber structures in Canada that are greater than 100 years old. The materials were tested in a cone calorimeter following a modified ASTM 1354 procedure. Hardwood samples typically exhibited a faster charring rate than the softwoods but the charring rates converged at 1.05 mm/min when exposed to higher fluxes of 50 kW/m2. As rehabilitation and readaptation may require performance-based approaches such as structural fire modelling, a provisional framework for a numerical model using LS DYNA for historic timber members is presented. The objective is to identify future research and testing areas to develop a higher certainty model. In the a-priori model presented, results showed conservative charring rate results with charring trends seen in the experiment generally being followed.

Automatic completion of geometric models from point clouds for analyzing historic timber roof structures

Automatic completion of geometric models from point clouds for analyzing historic timber roof structures

Experimental investigation of transition composite connections in historic style buildings

Historic timber buildings possess immense historical, artistic, and scientific value, but a few of them have survived after thousands of years of natural disasters and wars. Historic style buildings with modern construction material, imitating historic timber buildings forms, have emerged to inherit and promote traditional culture. To investigate the seismic performance of transition columns commonly used in historic style buildings, two full-scaled composite column transition (CCT) connections between steel reinforced concrete (SRC) square column and reinforced concrete (RC) circular column were designed and tested under invariable axial load and cyclic lateral load. Both failure patterns and force mechanism were studied based on the test process of the CCT connections. Then, the influence of axial compressive ratio on the mechanical behaviour of the CCT connections was assessed by looking at the hysteretic curves, backbone curves, characteristic loads, ductility, energy dissipation capacity and strength degradation. The results demonstrated that the failure patterns of the CCT connections were typical flexural failure, with the failure zone occurring at the upper column-root. The CCT connections exhibited excellent capacities of deformation and energy dissipation. As axial compression ratio increases, the failure of the CCT connection becomes more severe, leading to enhanced energy dissipation capacity. However, the strength and ductility of the CCT connection decrease. Based on the experimental results, an equation for calculating the lateral stiffness of CCT connections between SRC square column and RC circular column in historic style buildings was proposed, and verified to be accurate. The findings can provide necessary basis for the rational design and widespread application of historic style buildings.

Dendroarchaeology in Greece – From humble beginnings to promising future

It was back in the early 1960s when Bryant Bannister recognized the potential of dendrochronological research on wooden cultural heritage in Greece. More than two decades later, in the late 1980s, P.I. Kuniholm and C.L. Striker started collecting and analyzing tree-ring series from several historical buildings, forests, and archeological sites in Greece and the surrounding Aegean region. Despite highly promising results, especially from the northern and western parts of the country, dendroarchaeology did not attract much attention in the subsequent decades. It was only near the end of the 2000s that dendroarchaeology was reintroduced: first in Crete through the Cretan Dendrochronology Project, and then by another independent project concerning the restoration of a historical building on the island of Euboea. These isolated case studies inspired a five-year systematic research program called the “Balkan-Aegean Dendrochronology Project: Tree-Ring Research for the Study of Southeast-European and East Mediterranean Civilizations” (BAD Project). Dendroarchaeological surveys of historical buildings and archaeological sites were conducted throughout Greece with an emphasis on regions that had been previously ignored, such as the southern part of the country and the Aegean islands. Priority was given to buildings under restoration since in such cases original timbers were usually accessible and the architects, structural engineers, and archaeologists in charge were willing to collaborate. Our goals were not only to date timbers or provide information about the species used or the possible origin of the wood, but also to document the date, evolution, interventions and even the construction phases of historical buildings, as well as to help all those interested parties (academics, non-academics, researchers, professionals, local communities, etc.,) see the value of such information and how dendroarchaeology can contribute to the reconstruction of local history and the protection of cultural heritage. Tree-ring analysis led to the development of 18 chronologies from historical timbers and forests for six different species and different parts of the country from remote mountainous areas to small islands across the Aegean. The current dataset covers more than a thousand (1000) years and demonstrates the further potential of dendroarchaeology in the region.

TOWARDS AUTOMATIC DEFECTS ANALYSES FOR 3D STRUCTURAL MONITORING OF HISTORIC TIMBER

Abstract. Stability of historic wooden constructions is changing with time and should be inspected appropriately for risk assessment and prevention. The stability or strength values of built-in historic timber are difficult or even impossible to be derived without invasive investigation, but this is particularly problematic for the monitoring of heritage objects. Luckily there are some visible timber surface features, like knots and cracks, which can act as individual evidence to estimate the wood strength as well as to adjust its grade class indicator. In the final project, we aim to compare different approaches for 3D digital documentation of historic wood timbers and focus on automatic knot detection using AI techniques. A first feasibility study reported here provides a scientific baseline for the development of an automated method to analyse historic timber stability using 3D surveying and recognised surface features. First results about texture and resolution properties are discussed here.

Improvement effects of knee-bracing friction dampers on cyclic behavior of steel joints in antique buildings

To inherit the unique characteristics of historical timber architecture, the steel antique building (SAB) imitating ancient Chinese timber structures has been constructed using contemporary steel materials and fabrication techniques. These buildings typically exhibit premature yielding cracks and weak energy dissipation at the beam ends under seismic loads. To improve the seismic performance of SABs, two different types of friction dampers were deployed at the knee-bracing region around beam-column joints in SABs. First, cyclic loading tests on dampers indicate that both shear friction dampers and rotational friction dampers exhibit full hysteretic behavior, demonstrating an excellent and stable energy dissipation capacity. The friction coefficient of dampers with brass pads was theoretically calculated to be 0.35. Second, the quasi-static test showed that failure of steel joint specimens with knee-bracing dampers primarily occurred at replaceable angles in the beam-column connection region, which demonstrates that the repairability of steel joints in SABs can be greatly improved without overcomplicated labor. Adding knee-bracing dampers effectively postpones damage to the replaceable angles, which improves the strength, stiffness, and energy dissipation capacity of the steel joints significantly. The shear damper exhibits a more pronounced improvement in the overall structural seismic performance compared to the rotational damper with the same frictional sliding force. Moreover, numerical simulations showed that the strength of the proposed joints with knee-bracing friction dampers decreases with an increase in the axial compression ratio, while increasing the thickness of angles or the sliding force of dampers can effectively improve the seismic performance of the steel joints in SABs.

Comparative Study on Complete Characterisation of Elastic–Ductile Compressive Behaviour of Aged and New Norway Spruce Timber

ABSTRACT Material properties of historical timber structures may change over time due to decay, change of chemical composition of material, biological agents, climatic conditions, etc. Adequate bending performance requires stiffness and strength both in tension and compression, as well as sufficient ductility in compression. While the focus of most research is on the former quantities, the latter one is generally disregarded. This study gives a comparative analysis on complete characterization of compressive behaviour of recent and 60-years-old aged spruce timber (Picea abies). Parallel-to-grain compressive tests on small-sized specimens were conducted to obtain stress – strain diagrams and to determine failure modes. All material properties of stiffness, strength, and ductility were calculated for each specimen. It was concluded that elastic stiffness, elastic limit stress, and compression strength are virtually invariable after sixty years of service while the ductility decreased and the post-peak behaviour became more brittle. It is also found that end-rolling failure mode can yield the same elastic and stiffness properties as the standard kinkband failure. Climatic changes increase the risk of material deterioration prompting for more thorough monitoring and study of historical timber structures.

Developing millennial tree-ring chronology for Turku (Åbo) and comparing palaeoclimaticsignals inferred from archaeological, subfossil and living Pinus sylvestris datain Southwest Finland

Archaeological and living tree data were used to construct tree-ring chronologies over the medieval (AD 1183–1430) and recent (AD 1812–2020) periods in Turku, which is historically an important population centre in Southwest Finland and the country. Comparisons between the two tree-ring assemblages, and between the previously built chronologies from the Åland (historical timber) and Tavastia (lacustrine subfossils and living trees) sites, provided ways of understanding the growth patterns and their linkages to climatic, environmental, and edaphic factors. Tree growth in and around Turku was affected by warm-season precipitation and winter temperature. Similar relationships were previously evident also in the Åland tree rings, whereas the data from a wetter Tavastia site did not exhibit similar precipitation signal. The site conditions influence also the correlations which are higher between Turku and Åland than between Turku and Tavastia chronologies. Construction of long continuous chronology is impaired by human-related activities, the Great Fire of Turku in 1827 and logging, which have diminished the availability of dead and living-tree materials, respectively. These conditions lead to hardships of filling the gap between the medieval and recent periods and updating the archaeological datasets with compatible living-tree data, which are both demonstrated by our results.

Contemporary Fire Safety Engineering in Timber Structures: Challenges and Solutions

As environmental conservation and sustainability gain prominence globally, modern timber structures are receiving increased focus. Nonetheless, the combustible nature of timber raises significant fire safety concerns. This review explores the recent advancements in fire safety engineering for timber structures, emphasizing both contemporary high-rise buildings and historical timber constructions. It covers topics like inherently safer design principles, fire risk prediction, and evacuation methodologies. The review emphasizes the criticality of selecting suitable materials, structural design, firefighting systems, and advanced sensor technologies for early fire detection. Additionally, we analyze and compares various evacuation strategies, offering insights into the challenges and future directions for fire safety in modern timber structures.

Species and deterioration of woods used in a traditional Turkish house

This study identified the wood species and evaluated the weathering and biological degradation of historical timber from a traditional Turkish house in Konuralp, Türkiye. The wood material was obtained from the floorboards, window frames, cabinets, cripple studs, ceiling boards, and joists. The species were identified as Pinus spp. for the cabinet, window frame, and cripple stud, Abies spp. for the floorboards, Populus spp. for the ceiling boards, and Quercus spp. for the joist. The macroscopic observation revealed multiple types of degradation caused by weathering, fungi, and insect attacks. The cripple studs made of pine and the floorboards made of fir had become completely unusable due to insect damage. Relatively less biological damage was observed on the cabinet made of pine wood and the ceiling boards made of poplar wood.