Ancient Wooden Buildings Research Articles

Effect of slenderness ratio on axial compression behavior of circular wood columns strengthened with high-performance bamboo-based composites

Developing sustainable high-performance bamboo-based composites (HPBBC) with carbon sequestration benefits as reinforcement material is of great significance in promoting the application of HPBBC and securing ancient wooden buildings. Available column reinforcement methods have damage characteristics, which are unsuitable to be applied in ancient wooden columns because the ancient building needs to be preserved in the current conditions. The wooden column was bound with HPBBC and spaced steel strips to achieve damage-free strengthening. The slenderness ratio is an essential factor affecting the mechanical properties of wood poles, which is significant to be studied. The effect of the slenderness ratio on the axial compression behavior of circular wood columns strengthened with HPBBC was investigated in this study. The test results showed that the slenderness ratio significantly influences the failure mode, load-bearing capacity, and deformability of strengthened circular wood columns. The typical failure mode of short columns was a crushing failure, while the long columns were buckling failures. The load-carrying capacity and longitudinal strain of strengthened circular timber columns decrease significantly with increasing slenderness ratio. The lateral displacements or buckling appearance increases significantly with the increasing slenderness ratios of the strengthened timber column. A load-bearing capacity formula was proposed to predict the load capacity of strengthened circular wood columns based on their axial compression damage characteristics. The error between the calculated and tested results is less than 8.2 %.

Improving seismic performance for inclined historical building by using external protection structure: Case study of Yingxian wooden pagoda, China

Historical wooden buildings constitute a significant segment of the architectural heritage worldwide. However, these structures are susceptible to component deterioration and structural inclination, potential collapse due to material degradation and the impact of external loads. The fundamental objective in conserving these historical wooden buildings is to safeguard them from such catastrophic failures, thereby preserving their intrinsic value and extending their longevity. To address this issue, a scientific control method based on the principle of minimum intervention has been proposed, termed the “zero-interference method”. This approach is designed to mitigate the progression of structural inclination and enhance the seismic resilience of ancient wooden structures without imposing any disruptive influences. The ancient wooden building is surrounded by an external protection structure (EPS) that is connected to the inclined part. This study uses the FE model of the Yingxian wooden pagoda in China to analyze the structural responses in both pre- and post-reinforcement, validating the effectiveness of the method. Additionally, the parameters of the EPS are discussed. The results reveal that the zero-interference method can effectively mitigate the progression of structural inclination and reduce the seismic responses of the wooden pagoda. The maximum reduction of story drift can reach over 50 %. The wooden pagoda is connected to an EPSwith concentrically braced support by using BRBs, improving the seismic performance. Notably, this study offers a valuable contribution to the field, presenting a methodological framework for augmenting the structural rigidity and curtailing displacement in historical wooden buildings.

The organic–inorganic hybrid sol for the consolidation of decayed wood in architectural heritage

Generally, the mechanical property defects and surface cracks are often presented in partly decayed wood components that are treated with silicon-based inorganic consilidants. To solve the problem, an organic–inorganic hybrid sol for the conservation of decayed wood was developed in this work, in which the polyvinyl alcohol (PVA) was introduced into the silicon inorganic sol formed by the sol–gel process of ethyl orthosilicate and methyl triethoxysilane. The properties of decayed wood treated with the organic–inorganic hybrid sol were characterized by performance tester, microcomputer control electron universal tester, simulation of swelling-shrinkage and thermal gravimetric analyzer. The consolidation mechanism was affirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. The results revealed that the introduction of PVA into the hybrid sol led to a great improvement in comprehensive mechanical properties of the treated wood, accomplishing the swelling-shrinkage properties of the decayed area closer to those of sound area in wood. The improved properties could be ascribed to the hybrid gel coats formed on the surfaces of wood cells, which displayed a good performance in enhancing mechanical properties and thermostability. The hybrid sol can be used as a potential material to consolidate the partly decayed wood components for the protection of ancient wooden buildings.

Influence of Coal Mining on Historical Buildings: Case Study in Shanxi

Numerous historical buildings exist in Shanxi Province, a major coal producing area in China, so there exist many overlapping areas between ancient wooden buildings and coal mining. Coal mining in overlapping areas will lead to surface subsidence, which will have an impact on historical buildings. Based on the distribution of historical buildings and the distribution and mining of coal resources in Shanxi Province, this paper concludes that the overlapping areas of coal mining and ancient wooden buildings in Shanxi Province are mainly concentrated in Changzhi City, and the Lu'an mining area in Changzhi City is selected as the research object. In addition, using the gray correlation analysis method, the surface subsidence coefficient, which characterizes the intensity of mining subsidence, is used as the reference sequence. Seven factors selected from the geological conditions and mining conditions of the Lu'an mining area are used as the comparison sequence to calculate the gray correlation between each influencing factor and the surface subsidence coefficient, and to obtain that geological factors such as the nature of the overlying rock layer, bedrock thickness and dip angle of the coal seam, and mining factors such as mining height, average mining depth and working face size largely determine the surface subsidence coefficient. The surface subsidence in the overlap area could largely be influenced by geological factors such as the nature of the overlying rock layer, bedrock thickness and coal seam inclination, and mining factors such as mining height, average mining depth and working face size. Finally, we investigate the possible effects of surface subsidence on ancient wooden buildings in the overlapping area with the surface subsidence and formation mechanism and propose technical measures to reduce the effects of surface subsidence due to coal mining on historical buildings in the overlapping area.

Study on the mechanical characteristics of Xia-Ang in the Song-style Dou-Gong set on columns

As an important node in ancient wooden buildings, Dou-Gong serves functions such as energy dissipation and overhanging eaves. Xia-Ang plays an important cantilever role in Dou-Gong. To study the mechanical characteristics of Xia-Ang, we conducted horizontal quasi-static experiments and finite element numerical simulations to investigate two typical Song-style Dou-Gong sets on columns. The difference between the two types of Dou-Gongs is the presence of Xia-Ang components. The results of mechanical experiments showed that the hysteretic curves of the two types of Dou-Gong were in reverse “s” shape under the force from the beam direction, which has obvious pinch characteristics, and the Dou-Gong components were cracked to a certain extent. Under the force from the direction of the Fang, the hysteretic curve was complete, and no obvious splitting or warping components were found in the Dou-Gong. The influence of Xia-Ang on the mechanical characteristics of Dou-Gong was mainly reflected along the beam direction, but had no effect on the Fang direction. When the Dou-Gong was pushed by the beam, the horizontal stiffness of the Dou-Gong was strengthened by Xia-Ang, and the horizontal stiffness of the Dou-Gong with Xia-Ang was increased by 29.41% compared with that of the Dou-Gong without Xia-Ang. When the Dou-Gong was under tension, Xia-Ang weakened the horizontal stiffness by 23.75%. Two types of Dou-Gong were studied using the ABAQUS finite element method. The finite element model was verified and revised by comparing the simulation and experimental results. The numerical simulation results showed that when the beam was loaded, the horizontal stiffness of the Dou-Gong increased by 28.15% owing to the presence of Xia-Ang under the action of thrust. Under tensile force, the horizontal stiffness of Dou-Gong decreased by 24.26%.

Normal cloud model theory-based comprehensive fuzzy assessment of wooden pagoda safety

• It's the first time to apply normal cloud model into wooden pagoda safety assessment. • Two-way mapping of the "quantitative description-qualitative concept". • A four-level safety assessment index system. Currently the safety assessment of wood structure ancient buildings is mainly qualitative description, ignoring accurate quantitative calculation, and there are uncertain factors such as fuzziness and randomness that affect the results in the assessment process. Therefore, based on the cloud model theory of transformation between qualitative and quantitative uncertainties, this paper proposes a normal cloud model-based safety assessment approach for the protection research of wooden pagoda. A multi-level assessment system combining qualitative and quantitative indexes is constructed, and the comprehensive weight of the evaluation indexes is determined by combination weighting method. And combining with the scoring of evaluation indexes through quantitative analysis of point cloud, qualitative evaluation of experts, and published high-level papers, the comprehensive evaluation cloud model is constructed. According to the standard grade division, the criteria cloud model is constructed. And safety performance grade is determined by comparing the cloud similarity between the two clouds. Then this paper sets Yingxian wooden pagoda in China as an example, safety performance is quantified under this approach to determine its safety performance grade. The results show that the pagoda is the closest to third grade, in a certain dangerous state and consistent with the actual situation. The method takes into account the randomness and fuzziness factors, which makes assessment process more comprehensive and objective, provides a research paradigm for the safety assessment of ancient wooden buildings.

Risk Assessment and Monitoring of Termites in the Forbidden City under Global Warming

ABSTRACT Historical heritage is facing enormous challenges as a result of global warming. Termites are a significant pest in ancient wooden buildings and their area of activity is also expanding. According to historical records, Reticulitermes chinensis Snyder and Reticulitermes speratus Kolbe are the main species of Reticulitermes present in Beijing. A 40-year record of meteorological data, termite damage information published by the Chinese government and indoor environmental data show that the risk of termite damage to the Forbidden City is increasing. In the first two decades of the twenty-first century, two termite infestations occurred in the Forbidden City. Monitoring and control systems were applied immediately, the risk to each object storeroom and other termite-susceptible area was classified and monitored, and the termites were controlled successfully. With the rapid development of information technology, an advanced termite monitoring system has been introduced that is based on non-closed-loop electromagnetic induction, is fully automatic and gives remote real-time monitoring. LoRa technology was used for signal transmission between the termite monitoring station and the information collection. This signal transmission technology can overcome the signal-blocking effect of the numerous walls inside the Forbidden City, ensuring that the signal can be transmitted quickly and accurately as soon as termite infestation is detected. The non-closed-loop design allows the electronic components to be fully encapsulated, improves resistance to soil moisture and salt erosion, prolongs service life and ensures accuracy. The risk assessment and remote real-time monitoring technology introduced in this paper are of great significance for protecting ancient buildings in the cities of northern China.

Vibration reduction and isolation performance of a platform foundation and column base of an ancient wooden structure based on the energy transfer analysis

Wooden structures, as the most representative structural types of the ancient Chinese architecture, are very common and have a long history. The special construction methods adopted in ancient wooden structures, such as the platform foundations and plinth connections, enabled the ancient buildings to stand for thousands of years. However, research on the vibration reduction and isolation of the unique structures is insufficient. Thus, this paper investigates the vibration reduction and isolation performance of the platform foundation and column base of ancient wooden buildings, taking the 1500-year-old Feiyun wooden pavilion as a case study. First, using the acceleration RMS, the traffic-induced vibrations were analyzed in the time domain. It was found that the platform foundation tends to amplify the horizontal vibrations, while the column base tends to reduce them. Furthermore, background vibrations were eliminated from the measured data by using the principle of energy conservation. A frequency domain analysis of the processed data showed that the horizontal traffic-induced vibrations below 16 Hz were reduced by the platform foundation, and the column base had an obvious effect on the vibration reduction and isolation below 40 Hz. Both the platform foundation and the column base demonstrated a good effect on the reduction of traffic-induced vibrations in the vertical direction. The reported research results can be used as a basis for further studies on the dynamic performance of ancient wooden structures.

Experimental Study on the Fire Resistance Performance of Partition Board under the Condition of Small Fire Source

Fire safety of ancient wooden buildings is one of the most important issues in the world. In this paper, partition boards with different thicknesses from 15 to 25 mm were heated by a 15-cm-diameter pool fire and a methane Bunsen burner. The temperatures and the carbonization rate of partition boards were measured and analyzed. The results show that when a pool fire was used to heat the wood sample at a distance of 30 cm, two flames appear on the sample surface. When a Bunsen burner heats the sample, the sample is burned until the center point is burned through. The thickness of the sample is increased by 5 mm, and the acceleration time of the temperature rise rate at the center is doubled. Under the condition of a pool fire, the thickness of the sample is increased by 5 mm, and the average carbonization rate at the center point is reduced by 40%. Under the condition of Bunsen burner, the average carbonization rate of the center point decreases exponentially when the thickness of the sample increases by 5 mm. In the case of the same fire source, the carbonization rate of the samples with different thicknesses has the same change trend in the horizontal and vertical directions. Compared with the pool fire, the burn-through time of the center point of the sample is reduced in the case of the Bunsen burner for a sample of the same thickness, and the average carbonization rate of each measuring point increases.

The Influence of Environment on the Settlement of Historic Buildings in China

Chinese ancient wooden buildings prefer fronting water and with hills on the back. Therefore, some ancient buildings were built on the bedrock of the mountain. The uneven height of the building platform from the bedrock causes the uneven settlement of the foundation. Due to the disturbance of groundwater, the uneven settlement of the building foundation will also change due to the groundwater. This paper takes the Song Dynasty Jinci Goddess Mother Hall as an example to compare the settlement of the original foundation and the settlement of the repaired foundation. Summarize the effect of groundwater and the bedrock location of the settlement of ancient building platforms under different strengthening methods. The Flac-3D simulation software was used to simulate the foundation and load of the building. The numerical simulation results show that the settlement value after reparation is reduced by 84% compared with that before. The values of the settlement trend are similar to actual data, which has to guide significance for the prediction of building settlement and the protection of the building. Authors can provide references for future protection and the foundation reinforcement of similar buildings by comparing the foundation reinforcement methods by actual measurement and numerical simulation.

Novel Ti3C2Tx MXene/epoxy intumescent fire‐retardant coatings for ancient wooden architectures

AbstractMost of the ancient buildings are made of inflammable wooden structures, which have serious potential safety hazards. Applying fire‐retardant coating is one of the simplest and most effective means of fire prevention in ancient wooden buildings. In this work, we have demonstrated that the Ti3C2Tx transition metal carbide/carbonitride (MXene) was applied as the synergetic agent, waterborne epoxy resin as the film‐forming agent, ammonium polyphosphate, dipentaerythritol, and melamine (P‐C‐N system) as the intumescent fire‐retardant system to prepare Ti3C2Tx/epoxy intumescent fire‐retardant coating (TEIFC). The results showed that MXene has significantly improved the fire‐retardant performance of the coating. By incorporating 3 wt% Ti3C2Tx (TEIFC‐3, with 62 wt% P‐C‐N system), the coating displayed UL‐94 V‐0 rating with the limiting oxygen index value of 38%. In addition, the combination of Ti3C2Tx and P‐C‐N system enhanced the Shore hardness of the coating to 95 SHD (TEIFC‐3). Furthermore, TEIFC‐3 presented high thermal stability with the THRI of 177.0°C and Tdmax of 380.5°C. This work provides a novel strategy for the design and preparation of intumescent fire‐retardant coating, which will greatly broaden the industrial applications of MXene‐based polymer composites in the field of fire prevention of ancient buildings.

Application and Progress of Reinforcement Technology for Chinese Ancient Buildings with Wood Structure

The ancient wooden buildings have been preserved after years of wind and rain, as well as damaged to different degrees. Most of the ancient wooden buildings are important cultural resources of the country; they are precious cultural heritages, and not recoverable. Therefore, it is particularly important to protect these ancient buildings. This paper analyzes and discusses the destruction form, repair principle and reinforcement method of ancient wooden buildings, and puts forward the shortcomings of existing technology, hoping to provide reference for effective protection of ancient wooden buildings in the future.

The predictive research of ancient wooden building internal defects compressive bearing capacity based on nondestructive testing methods

131 small specimens and 10 scaled wood column specimen (including 2 complete specimen and 8 with different defect locations and sizes and the type is core cavity) are made with the reference to Building Formulas to research the ancient wooden building internal defects compressive bearing capacity prediction. Some researches on the relationship between the small specimens wave resistance modulus and mechanics, nondestructive testing and internal defects wood column compressive bearing capacity prediction as well as dangerous section judgment and so on. The test result suggests that there is a significant positive correlation between the wave resistance modulus and the compressive strength (r2 = 0.635), which is more accurate than single parameter; internal defect specimens with various locations have an impact on overall compressive bearing capacity and with the defect sectional area expanding, the compressive bearing capacity decreases continuously, the cross-sectional area of the defect is proportional to the attenuation of the relative resistance value; nondestructive method can better predict wood column ultimate compressive bearing capacity and the error is predicted less than 10%. Nondestructive testing method can better determine the most dangerous section of the test piece compared with destruction morphology results. The wooden components quality can be safely evaluated on the premise that the originality of the ancient buildings is preserved and valid data references can also be provided for renovation and reinforcement of ancient buildings wooden components.

Research on damage and identification of mortise-tenon joints stiffness in ancient wooden buildings based on shaking table test

Based on the shaking table tests of a 1:3.52 scale one-bay and one-story ancient wooden structure, a simplified structural mechanics model was established, and the structural state equation and observation equation were deduced. Under the action of seismic waves, the damage rule of initial stiffness and yield stiffness of the joint was obtained. The force hammer percussion test and finite element calculations were carried out, and the structural response was obtained. Considering the 5% noise disturbance in the laboratory environment, the stiffness parameters of the mortise-tenon joint were identified by the partial least squares of singular value decomposition (PLS-SVD) and the Extended Kalman filter (EKF) method. The results show that dynamic and static cohesion method, PLS-SVD, and EKF method can be used to identify the damage degree of structures, and the stiffness of the mortise-tenon joints under strong earthquakes is reduced step by step. Using the proposed model, the identified error of the initial stiffness is about 0.58%-1.28%, and the error of the yield stiffness is about 0.44%-1.21%. This method has high accuracy and good applicability for identifying the initial stiffness and yield stiffness of the joints. The identification method and research results can provide a reference for monitoring and evaluating actual engineering structures.

Cyclic behavior of Chinese ancient wooden frame with mortise–tenon joints: friction constitutive model and finite element modelling

The beams and columns in Chinese ancient wooden buildings were connected with mortise–tenon joints, which are semi-rigid due to the friction and squeezing deformation between mortise and tenon. In this paper, a friction constitutive model for the friction behavior between mortise and tenon was proposed based on the modern frictional theory. A series of surface topography and hardness tests were conducted to obtain some parameters used in the friction constitutive model. A finite element (FE) model of a Chinese ancient wooden frame with mortise–tenon joints under reversed cyclic loading was performed based on the proposed friction constitutive model, and a FE model using a constant friction coefficient was also carried out. Experimental results were used to validate the results modeled by the two models, and better agreement of the proposed model was observed.

Dynamic field monitoring data analysis of an ancient wooden building in seismic and operational environments

The engineering background of this article is an ancient wooden building with extremely high historic and cultural values in Tibet. A full understanding of the dynamic behaviour of this historic building under in-service environments is the basis to assess the condition of the structure, especially its responses to earthquake, environmental and operational loading. A dynamic monitoring system has been installed in the building for over one year and the large amounts of high quality data have been obtained. The paper aims at studying the dynamic behaviour of the wooden building in seismic and operational conditions using the field monitoring data. Specifically the effects of earthquake and crowd loading on the structure´s dynamic response are investigated. The monitoring data are decomposed into principal components using the Singular Spectrum Analysis (SSA) technique. The relationship between the average acceleration amplitude and frequencies of the principle components and operational conditions has been discussed. One main contribution is to understand the health condition of complex ancient building based on large databases collected on the field.

Ancient wooden buildings as monuments of technique and technology

The most valuable monuments of the architecture and vernacular wooden buildings testify the progress of the development of building techniques during the period of time when they were created. Wooden vernacular objects which survived can be recognized as documents of fundamental professional knowledge of builders and their own innovations. During the conservation process of a wooden building we ought to recognize and protect all visible traces of old building techniques used at that time. The properties and ways of using the building materials which were usually not durable or good enough have to be taken into account nevertheless.

Typical Brackets Dimensional Numerical Simulation of the Wooden Structure

Brackets is the ancient Chinese wooden building unique ways and one of the main features of the structure. Its dual function of both structural and architectural: An important component of both the structure itself, because of its flexible features tenon, the dynamic response of the structure can absorb greater energy, play a good role in the earthquake; But it is also a special architectural ornament, can play the effect of beautifying buildings. Therefore, this paper based on the finite element software ABAQUS brackets by the force of the mechanism of failure modes and numerical simulation analysis for the brackets and the whole structure of the wood to provide a scientific assessment and reinforcement.

Material Properties Test of Wooden Architecture and its Mechanical Properties

Ancient Chinese architecture is the most representative in Chinese ancient civilization. Now preserved ancient ruins are extremely valuable in historical and cultural value, artistic value and scientific value, so the research on the characteristics of ancient building structures in China and its seismic performance have important realistic significance. On the basis of the existing Chinese ancient wooden buildings, the paper discusses the structure performance of Chinese Ancient Timbering Buildings. According to the existing theoretical knowledge, the paper elaborates the reasons for using the wood of Chinese ancient architecture and analyses the basic characteristics of the ancient wood as building materials. We take the experiment of wooden mechanical property test to study the characteristics of material better, and emphasis narrates the whole process of wood bending strength test, then get the results of wood mechanical characteristics.

Aseismic Constitution Problems and Strengthening Methods of Chinese Ancient Wooden Buildings

Chinese ancient wooden buildings have good aseismic constitutions to survive sorts of natural disasters. However, under earthquakes damages still occur on some of them. To protect Chinese ancient wooden buildings, typical aseismic constitution problems as well as strengthening methods of their members were studied by classification and statistical methods. Based on survey results on large number of Chinese ancient wooden buildings, typical aseismic constitution problems were summed up, causes for the problems were analyzed and the corresponding strengthening methods were proposed. By 2 compared examples, typical strengthening methods were further demonstrated. Results show that typical aseismic constitution problems of Chinese ancient wooden buildings include decay of column root, slack of Tou-Kung, tenon pulled out of mortise, cracks of beam and column and so on; to solve these problems, methods such as replacement, wrap, connection, ensemble and so on are feasible.