This study investigated the seismic performance of multi-story traditional hybrid pavilion-style timber structures through shaking table tests and numerical modelling. A 1/4.5 scaled model of the Guangyue Tower in Northern China was fabricated and subjected to shaking table tests. Three ground motion records with different intensity levels were selected as seismic excitations. The damage patterns, dynamic characteristics, and responses of the model were analyzed based on the test results. The results showed that significant joint loosening and cracking were observed in the model under strong seismic excitation, which led to a 22.8

The brick wall-timber frame system in traditional dwellings is a core structural form that carries historical and cultural value while ensuring building safety. However, the out-of-plane mechanical performance of the system is affected by the properties of connecting components. Improper parameter design of metal connectors is prone to induce out-of-plane collapse failure of brick walls, which seriously threatens the safety of building structures. To reveal the influence mechanism of metal connector parameters on the out-of-plane mechanical performance of this system and clarify the regulatory effect of key parameters of metal connectors on the cooperative working performance between brick walls and timber frames, this study established 4 sets of 1:2 scaled brick wall-timber frame systems using ABAQUS finite element software. The accuracy of the models was verified by comparison with experimental data. Based on this, the influence laws of the thickness, width, length, and material properties of the diamond-shaped anchorage end of metal connectors on the out-of-plane mechanical performance and failure mechanism of the system were investigated. The results show that the width and length of the diamond-shaped anchorage end of metal connectors have the most significant influence on the out-of-plane deformation of brick walls, with the maximum reduction of 24.6% in the out-of-plane deformation of brick walls. Metal connectors with large diamond-shaped anchorage ends play a more prominent role: the peak stress of through-wall reinforcement is increased by up to 3.09 times, and such connectors significantly reduce the peak relative displacement between columns and brick walls, with the maximum reduction of 42.9%. And the recommended value range of the ratio of the diamond-shaped anchoring end area to the wall area is proposed. The research results provide a theoretical basis for the out-of-plane mechanical performance improvement and reinforcement of brick wall-timber frame systems.

This study fabricated historical brick column specimens with mortar joint spalling. Modified composite sticky rice-lime mortar and natural hemp fiber rope were adopted and horizontal mortar joint grouting and fiber rope reinforcement were implemented to prepare performance-enhanced historical brick column specimens. The compression failure morphology and mechanical properties of the specimens with different strengthening conditions were studied, and the variation patterns of mechanical performance indicators with the strengthening conditions were analyzed. The calculation formula for the compressive strength was proposed, and the full stress-strain relationship model under compression and the crack length development model were established. The results show that the non-strengthened brick columns exhibit brittle failure morphology under compression, and the compressive strength and deformation modulus decrease with the increasing mortar joint spalling depth. The crack development process of reinforced brick columns under compression presents ductile characteristics. The compressive strength and crack density increase obviously and mortar joint grouting-fiber rope reinforcement significantly enhances the elastoplastic deformation capacity. The compressive strength, crack density, and elastic modulus of brick columns with the 12.5% grouting depth ratio and 0.125% reinforcement ratio increase by 57.4%, 7.9%, and 29.4%, respectively. The proposed strengthening method provides good engineering applicability.

This study investigated the seismic performance of multi-story timber structures using the Guangyue Tower as a prototype. A 1:4.5 scale model was fabricated and subjected to a series of shaking table tests. The Taft and El Centro records and synthetic ground motions were applied as input seismic excitation, where the peak ground acceleration (PGA) was set to 0.138 g, 0.375 g, 0.525 g, and 0.775 g. Measured dynamic responses included natural frequencies, damping ratios, acceleration amplification factors (AAFs), inter-story drift angles, inter-story shear forces, and energy dissipation, all of which were analyzed to assess structural performance. The results indicated that as PGA increased, the first-and second-mode natural frequencies of the model decreased by 22.8% and 7.8% respectively, while the corresponding damping ratios increased by 59.3% and 18.7%. For all input motions and stories, AAFs remained below 1 and decreased with increasing PGA. For a rare earthquake of seismic intensity 7, the maximum inter-story drift angle was 1/29, and no evident tilting damage occurred. Story energy dissipation increased with PGA and attained a maximum of 2048 J, which indicated a substantial seismic energy dissipation capacity. This structural model exhibited excellent seismic performance. The first and second floors were identified as weak stories and should be prioritized for renovation and structural reinforcement.

Using cellulose fiber and fly ash as modifiers of traditional sticky rice lime paste, this study prepared six groups of modified sticky rice lime composites with different modifier proportions. Consistency measurements, mechanical tests, freeze-thaw (F/T) cycle tests, and F/T-chloride erosion coupling cycle tests were conducted on the composites. XRD, SEM/EDS, and NMR were performed before and after F/T-chloride erosion for further analyses. The performance enhancement mechanisms of the composites and their deterioration under the coupled effects of F/T and chloride erosion cycles were systematically investigated. The results indicated accelerated hardening, improved mechanical strength, and effectively inhibited microcrack propagation during F/T cycles by cellulose fiber. However, excessive cellulose fiber compromised the F/T resistance of the composite. The cellulose fiber-fly ash combination produced a dense microstructure by significantly refining the pore of the composite and reducing its porosity. Meanwhile, the pozzolanic reaction products adsorbed and immobilized chloride ions while simultaneously improving fiber-matrix interfacial adhesion and interfacial transition zone compactness, thereby substantially enhancing the durability of the composite under the coupled effects of F/T cycles and chloride erosion. The composite paste with 1% cellulose fiber addition and a 25% fly ash substitution ratio exhibited favorable mechanical strength and excellent resistance to the coupling F/T and chloride erosion cycles, while also achieving substantially reduced CO2 emissions during production. The findings could provide theoretical insights and practical references for developing repair binders for historical masonry restoration.

The effects of replacing calcined clay with sewage sludge ash (SSA) treated under room temperature and high temperature ranging from 500 °C to 900 °C in limestone calcined clay cement (LC3) have been investigated in this paper. The optimal calcination temperature for SSA was found to be 800 °C based on the results of strength and microstructure observations. The main inorganic components of sludge ash are Fe2O3, SiO2, Al2O3, and CaO, which are very similar to the components of calcined clay in LC3, but with a very high content of Fe2O3 (55–61%) and P2O5 (9–10%). With different levels of the replacement of calcined clay with calcined SSA, setting time, compressive strength, XRD, TG/DSC, and SEM analyses of the modified LC3 pastes were conducted to identify the chemical compositions, physical properties, hydration products, microstructure, and the heavy metal contaminants within the pastes, which were compared to the results for normal LC3 paste. The incorporation of SSA significantly altered the morphologies of Ca(OH)2 and CaCO3, as well as modified the microstructure of the LC3 paste. In comparison to the pure OPC group, the LC3 pastes containing SSA exhibited a reduced Ca(OH)2 content and an increased CaCO3 content. Furthermore, the modified LC3 pastes with calcined SSA effectively facilitated the immobilization of heavy metal ions in SSA. The findings indicate the potential viability of utilizing calcined SSA as a replacement for calcined clay in LC3.

This study investigated the dynamic performance of a multi-story Chinese traditional timber structure with seismic damage through shaking table testing. A 1/4.5 scaled model of the Guangyue Tower that located in Northern China was fabricated. The model was first shaking table tested to produce seismic damage, and then second time subjected to earthquake excitations. Test results, including damage patterns, dynamic characteristics and responses of the intact and damaged models, were obtained. Shear force resistance and energy dissipation capacity of both models were also evaluated. The impact of the seismic damage on the model's seismic performance was indicated. The results showed that the intact model mainly happened with coordination failure of timber infill walls and frames. With the timber infill walls demolished, the damaged model was observed with significantly looseness and cracking in joints after experiencing strong earthquakes. Although the model had no remarkable residual lateral deformation, its fundamental frequency after damaged decreased 18.6 %. The seismic damage decreased the model acceleration response by 11.1 %, and increased the maximum interstory drift up to 47.8 %. As a result of the moderate acceleration response, the base shear force of the model reduced 20.2 %, but the energy dissipation increased 28.9 % owing to larger lateral deformation. The findings of this study could provide reference in the seismic protection and rehabilitation of multi-story traditional timber structures.

Traditional timber structures in East Asia are of great historical and cultural value. This study investigated the seismic performance of Guangyue Tower (GYT) in Northern China combined in-situ dynamic test and numerical modelling. An ambient test was carried out to identify the natural frequencies and model shapes of the tower. Then a numerical model, whose mechanical parameters were determined based on existing experimental research on traditional joints, was developed and validated by the ambient test results. Time history analysis was performed to assess the seismic performance of GYT. The in-situ dynamic test indicated that the first and second-order natural frequencies of the GYT were about 1.6 Hz and 3.3 Hz, and the first and second-order mode shapes corresponded to the shear and shear-bending modes, respectively. The numerical analysis indicated that the acceleration amplification coefficients of each story were generally less than 1.0, and decrease with increasing seismic wave intensity. The maximum story drift of the structure was about 1.4% under the excitation of a rare earthquake, indicating excellent seismic resistance of GYT. This study proposed a useful method to assess the seismic performance of traditional timber structures.

This paper evaluated the rotational performance of glulam post-to-beam joints with concealed beam-hanger (CBH) connectors through tests, numerical analyses, and theoretical derivations. Six monotonic and three cyclic tests were conducted to study the influence of the length of tensile screw and stiffener shape on the connection's rotational performance. The test results highlighted two distinct failure modes: (I) Withdrawal failure of screws, and (II) Tensile failure of screws. The stiffened CBH connection demonstrated a 76.3 % increase moment resistance and a 171.2 % increase in initial stiffness compared to non-stiffened connection, with 40.0 % reduction in ductility. Two simulation approaches were proposed to model the rotational performance the CBH connection, including three-dimensional detailed finite element (FE) models developed in ABAQUS and simplified models established in OpenSees. Parametric analysis of the detailed models demonstrated that the moment resistance of the CBH connections exhibited an approximately linear relationship with the screw diameter. Finally, an analytical model was proposed, offering slightly conservative estimates of the moment resistance for stiffened CBH connections.

This study investigates the utilization of Bayer red mud (BRM) from Shandong Xinfa Group as a partial cement replacement, with replacement levels of 0.5%, 1%, 5%, 10%, and 15% by mass. The effects of BRM incorporation on setting time, compressive strength (at 3 and 28 days), and microstructural properties were systematically evaluated. Results indicate that the addition of BRM prolongs setting times but remains within standard limits. Compressive strength remained comparable to the control group at replacement levels up to 5%, while higher substitutions (10% and 15%) led to significant reductions. Microstructural analyses with XRD, TG/DTG, and SEM revealed that BRM primarily acts as a micro-filler and nucleation site, participating partially in hydration reactions. Leachability tests (TCLP) confirmed that all heavy metal concentrations in BRM-blended mortars were below regulatory thresholds, demonstrating minimal environmental risk. The findings support the feasibility of using Xinfa BRM as a supplementary cementitious material at doses below 10%, contributing to sustainable solid waste management in the alumina industry.

This study fabricated ancient brick column specimens with two different mortar joint spalling depths based on the common material deterioration mode of ancient masonry. Specifically, modified composite sticky rice-lime mortar and natural hemp fiber rope were used as the raw materials, and horizontal mortar joint grouting and fiber rope reinforcement methods were adopted to prepare performance-enhanced ancient brick column specimens with six different strengthening conditions. Through uniaxial compression tests, the compression failure morphology and mechanical properties of the specimens under different strengthening conditions were studied, and the variation patterns of mechanical performance indicators with the strengthening conditions were analyzed. The calculation formula for the compressive strength of performance-enhanced ancient masonry was proposed, and the full stress-strain relationship model under compression and the crack length development model were established. The results show that the non-strengthened brick columns exhibit brittle failure morphology under compression, and the compressive strength and deformation modulus decrease with the increasing mortar joint spalling depth. The crack development process of reinforced brick columns under compression presents ductile characteristics. The compressive strength and crack density increase with an increasing grouting depth and mortar joint grouting-fiber rope reinforcement significantly enhances the elastoplastic deformation capacity of brick columns under compression. Under the 25% grouting depth ratio, the characteristic stress and corresponding deformation modulus of the stress-strain curve increase first and then decrease with the increasing fiber rope reinforcement ratio. The compressive strength and crack density of ancient brick column with the 12.5% grouting depth ratio and 0.25% reinforcement ratio increase by 57.1%, 24.7%, respectively. The established formula and models can clearly describe the evolution of mechanical properties of ancient masonry, offering good engineering applicability.

Sludge is a semi-solid waste generated during the process of wastewater treatment. Due to the addition of polymerized ferric chloride in the flocculation process, the sludge produced by the sewage treatment plant in Liaocheng Jiaming Industrial Park contains a high content of iron oxide. In this paper, chemical analysis and particle size analysis of local sludge and sludge ash were conducted. In order to assess the potential of substituting cement as cementitious material with different dosages of sludge or sludge ash with high iron oxide content, setting time, compressive strength, microscopic analysis using microscopic testing (XRD, TG/DTG, SEM) and a toxicity characteristic leaching procedure (TCLP) were analyzed. These procedures determined the physical properties, compressive strength, hydration products, microstructure, and heavy metal contaminants of cement slurries replaced by local sludge or sludge ash with different dosages of high iron oxide content. The results show that less than 5% of local sludge or sludge ash can be incorporated into cement slurry as an alternative cementitious material for solid waste disposal.

Aiming at the limitations of the curvature mode index for structural small damage identification, a new method of structural damage identification based on the combination of curvature mode and wavelet transform is proposed in this paper, which has significant damage identification capability. By combining numerical simulation and experimental analysis, the applicability of the wavelet coefficient difference index to wood beams and wood frames at different damage locations and degrees is investigated. The results show that the method determines the damage location of the structure based on the sudden peak of the wavelet coefficient difference index and estimates the damage degree of the structure by fitting the relationship equation between the wavelet coefficient difference index and the damage degree.

In situ dynamic testing is conducted to study the dynamic characteristics of the wooden structure of the North House main hall. The velocity response signals on the measurement points are obtained and analyzed using the self-interaction spectral method and stochastic subspace method, yielding natural frequencies, mode shapes, and damping ratios. This study reveals that the natural frequencies and damping ratios are highly consistent between the two methods. Therefore, to eliminate errors, the average of the results from both modal identification methods is taken as the final measured modal parameters of the structure. The natural frequencies of the first and second order in the X direction were 2.097 Hz and 3.845 Hz and in the Y direction were 3.955 Hz and 5.701 Hz. The modal frequency in the Y direction of the structure exceeds that in the X direction. Concurrently, a three-dimensional finite element model was established using ANSYS 2021R1, considering the semi-rigid properties of mortise–tenon connections, and validated based on in situ dynamic testing. The sensitivity analysis indicates adjustments to parameters such as beam–column elastic modulus, tenon–mortise joint stiffness, and roof mass for finite element model refinement. Modal parameter calculations from the corrected finite element model closely approximate the measured modal results, with maximum errors of 9.41% for the first two frequencies, both within 10% of the measured resonant frequencies. The adjusted finite element model closely matches the experimental results, serving as a benchmark model for the wooden structure of North House main hall. The validation confirms the rationality of the benchmark finite element model, providing valuable insights into ancient timber structures along transportation routes.

The assessment of concrete structure durability in chlorine environments is significantly impacted by the uncertainty inherent in existing durability models. It introduces an integrated approach for updating these models based on the detection information of existing structures. This approach narrows the gap between theoretical predictions and observed structural durability. Specifically, we refined the probability model of critical chloride content by analyzing steel bar corrosion sample proportions using Bayesian theory for greater accuracy. The enhanced model enables more reliable life expectancy prediction, forming a solid foundation for maintaining and strengthening existing structures. This method was demonstrated through a case study of a reinforced concrete industrial building with a service life of 12 years.

The seismic response of palace-style timber structures is closely related to the rocking characteristics of column. To accurately describe the dynamic characteristics of timber structures, a nonlinear rotational spring is employed to simulate the rocking behavior of column base joints under seismic excitation. Firstly, a spring-rigid rod analysis model that comprehensively considers the nonlinear properties of column base joints, mortise-tenon joints, and bracket set joints is proposed, and a simplified lumped mass model is obtained through centroid method and equivalent stiffness method. The accuracy of the simplified model is verified through shake table tests, and nonlinear dynamic response time-history analysis of the structure is conducted. Based on the verified simplified model, the influence of tenon-mortise joint reinforcement on the seismic displacement response of the structure was further investigated. It was found that carbon fiber sheets reinforcement increased the initial stiffness of the joints by 1.45 times and reduced the displacement response of the structure by 15%. Additionally, the optimal stiffness enhancement of column frame mortise-tenon joints range from 4 to 6 times.

This study explored the characteristics and freeze-thaw resistance of traditional sticky rice-lime paste modified with metakaolin and hemp fibers. Eight types of sticky rice-lime composites were fabricated. Their physico-mechanical properties, freeze-thaw cycling resistance, and resistance against the coupling effect of freeze-thaw and chlorine salt erosion were fully evaluated. The mineralogical, infrared spectral, morphology, and pore distribution characteristics of composites were investigated through XRD, FTIR, SEM, and NMR analyses. Moreover, the mechanisms of performance enhancement and durability failure were examined. The results demonstrated improved consistency, shrinkage, surface hardness, and mechanical strength of modified composites. Metakaolin and hemp fiber effectively enhanced compressive and flexural deformability, but hemp fiber adversely affected flexural stiffness. Gelatinized sticky rice regulated calcium carbonate crystalline phases. By incorporating hydrophilic hemp fiber and pozzolanic metakaolin into composites, the pore structure was refined, the porosity was reduced, and a dense microstructure was formed. After freeze-thaw cycles, 1% fiber addition could facilitate desirable surface alteration, mass variation, RDEM, and strength and stiffness retention. In addition, 25% metakaolin substitution enhanced the resistance of pore structure against chlorine salt corrosion. These results indicate that the prepared fiber-reinforced hydraulic sticky rice-lime composites have excellent conservation properties.

In the paper, a simple-supported wooden beam is used as the research object to identify the damage of the wood beam by finite element analysis and experimental research. First, ANSYS was used to establish the solid finite element model of the wood beam before and after the damage, and then the discrete wavelet transform was performed on the curvature mode of the wood beam before and after the damage, and the wavelet coefficient difference index was obtained after obtaining the high frequency wavelet coefficients. Then, the damage location of the wood beam was judged according to the sudden peak of the wavelet coefficient difference index, and the damage degree of the wood beam was estimated by fitting the relationship between the wavelet coefficient difference index and the degree of damage. Finally, the index was verified by the wooden beam test. The results show that the wavelet coefficient difference index can accurately identify the damaged location of the wood beams. The degree of damage to the wood beams at the damage location can be quantitatively estimated by fitting the relationship between the wavelet coefficient difference index and the degree of damage at the damage location. The research results provide a theoretical basis to identify wooden beam damage.

In order to better explain the phenomenon of wood cracking, based on the related literature at home and abroad, this paper summarizes the research status of the causes of wood cracking from the aspects of wood micro–properties, such as the release of wood growth stress, anisotropy, water gradient and the response of wood micro–structure to the change of external air temperature. The microscopic essence of wood cracking lies in the rupture of cell wall, and wood is influenced by factors such as wood species, interception position, tree height,growth ring density, etc., which makes it easy to form residual stress such as growth stress, shrinkage stress and drying stress in wood, which leads to wood cracking. Finally, the research prospect of longitudinal growth of trees,constitutive relation of wood properties, factors affecting wood cracking, etc.