Mortise-tenon Joints Research Articles

Experimental and Parametric Study on Rotational Performance of Through-Tenon Joints in Traditional Timber Structures

ABSTRACT The rotational capacity of mortise-tenon joints is crucial for stability in traditional timber structures. However, these joints are influenced by various factors such as environmental conditions and internal features, impacting their rotational performance over time. To assess these influences, four groups of through-tenon joints with different small and large tenon lengths were constructed and tested. Deformation characteristics, hysteresis, bearing capacity, stiffness, and energy consumption of the joints were investigated. Finite element models were created and verified through testing. An orthogonal design scheme analyzed the effects of parameters and their interactions on rotational performance. The results indicated that increasing the length of the smaller tenon improved tenon pull-out length and ductility, while simultaneously reducing bearing capacity, stiffness, and energy dissipation. Tenon dimensions and the ratio of small tenon length to total tenon length were found to significantly impact peak moment. Critical parameters affecting rotational performance included tenon length, elastic modulus perpendicular to the grain, and the gap between the tenon and mortise.

Margin of bearing capacity of one-way straight mortise-tenon joints based on inspection of apparent damage and rotation angle

In essence, safety evaluation of damaged mortise-tenon joints (MJs) involves checking whether the joints have sufficient residual bearing capacity. However, the load, which is necessary in the calculation process, is difficult to observe in practice, resulting in insufficient reliability of the evaluation results. Thus, this study proposes the concept of a margin of bearing capacity (MBC) of an MJ and presents a calculation method for assessing the safety of one-way straight mortise-tenon joints (OSMJs). In the calculating process, the load was replaced with the observed apparent damage and rotation angle. First, the MBC includes the influence of joint damage and rotation angle on the residual moment bearing capacity of the joint. Second, the apparent damage to an OSMJ is simplified to average section loss rates in the height and width directions, which reduces the amount and difficulty of data acquisition. Third, the damage model of an OSMJ included in the proposed calculation method establishes the transforming relationship between the measured average section loss rate and the damage setting on the model, and avoids the influence of uneven distribution of the actual size reduction on the calculation of the residual moment bearing capacity. The results of unidirectional pushover tests of several damaged and intact OSMJ models showed that most absolute errors between the calculated and measured MBCs were less than 0.04, indicating the accuracy of the proposed method for practical safety assessment of damaged OSMJs.

The Analysis of Impact on Fire Resistance of Mortise-tenon Joint in Different Connection Mode

In order to analysis of impact on fire resistance of mortise-tenon joint in different connection mode, four types of mortise-tenon Joints models are made by Pinus yunnanensis. And the combustion phenomena and carbonization of mortise-tenon joint are studied. Results of experiment show that the sequence of fire resistance in descending order is: Mantou mortise-tenon Joint, dovetail Joint, Ban mortise-tenon joint, Shizigutou mortise-tenon joint. The results can provide the theoretical base for fire protection of classical wood construction.

Experimental study on the seismic performance of a full-scale two-story traditional timber frame on sloped land

In traditional timber structures built on hilly areas, columns of varying lengths are utilized to accommodate sloped terrain. This structural feature renders these structures more susceptible to seismic damage than structures built on flat land. To investigate the seismic performance of traditional timber structures on sloped land, the quasi-static test was conducted on a full-scale two-story timber frame on sloped land (FSL), while an identical frame on flat land (FFL) was served as a comparative reference. This study analyzed the deformation characteristics, bearing capacity, and energy dissipation capacity of the frame on sloped land, as well as its weak positions and failure mechanisms. The test results indicate that the frame on the upper ground is the weak position compared to the frame on flat land. Short columns of the upper frame have greater inclination angles, leading to larger pull-out lengths of the mortise-tenon joints, and the column foot becomes more susceptible to slipping and lifting. Although the FSL has a greater bearing capacity than the FFL under the same horizontal displacement, it experiences a more significant deformation and is more prone to tenon failure and column foot sliding out of the foundation stone. With excessive deformation, gravity becomes a detrimental factor for structures on sloped land to resist horizontal overturning moments, which would accelerate the collapse of the structure.

Experimental study on seismic performance of Chinese traditional mortise and tenon joints with different lengths that tenons pull out of mortise

This paper presents the results of a study on seismic performance of mortise-tenon joints with different lengths that tenons pull out of joints. Three 1:3.52 scaled mortise-tenon joint specimens were fabricated: one with through-tenon joints, one with half-tenon joints, and one with dovetail joints. Seismic data of the joints, such as hysteretic curves, skeleton curves, stiffness degradation rules, and energy dissipation capacity curves, were obtained by low-cycle reversed loading test. The influence of lengths that tenons pull out of joints on the mortise-tenon joints was analyzed. The seismic performance of three types of mortise-tenon joints was compared. The results showed that all hysteretic loops are z shaped. The seismic performance of the through joint was the best among three types of mortise tenon joint. The length that the tenon pulls out of the joint significantly affected the performance of the mortise and tenon joints.

Earthquake wonders: High school investigation in mortise tenon structures

Frequent global earthquakes lead to catastrophic property damage and casualties due to building collapses. However, the 1976 Tangshan Earthquake showcased an exception: the Forbidden City, constructed with wooden materials and featuring mortise-tenon structures, remained unscathed among surrounding destruction. This study investigates the earthquake-resilient attributes of wooden mortise-tenon joints utilizing economical high school equipment. An innovative low-cost sensor system, featuring custom instrumented hammer, is developed and validated. Calibration of the hammer's impact force employs correlation with acceleration data from a standardized scale weight during impact. The system's reliability is tested by comparing resonance frequencies from Finite Element modal analysis and experimental data for a cantilever beam. Impact hammer tests assess frequency response and damping across buildings with various joint configurations. Mortise-tenon joints display augmented frictional damping due to internal displacement. Through simulated vibration acceleration responses, a crucial finding emerges---integration of mortise-tenon joints translates to an impressive 11.0% reduction in earthquake vibrations. This research underscores the potential of accessible high school devices in advancing seismic engineering insights.

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

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

Application of Additive Manufacturing Technology for Chair Parts Connections

Additive manufacturing (AM) is a potential technology to be applied for replacing wood joints in the furniture industry. Overall, 3D-printed connectors have a lot of advantages in chair construction: the possibility of improving the design by using colored materials and new concepts with no limits of shape and size, avoiding the use of synthetic materials such as adhesives and finishing materials. The present research shows the results of the research conducted on 3D-printed connectors for a chair leg-stretchers joint. Larch (Larix decidua Mill.) wood was used for chair components and selective laser sintering (SLS) technology was employed for the 3D-printing connector designed to assemble the chair elements. Diagonal tensile and compression tests were performed on the L-type joints with 3D-printed connectors and the bending moments were determined and compared to the results obtained after testing the leg-stretchers mortise–tenon joints made of larch wood, taken as a reference. Micrograph investigation was finally performed on the broken areas of the 3D-printed connectors as a result of mechanical testing failures. The results show that the SLS printing technology applied to build the connector does not ensure enough strength to the assembly, and changes in printing parameters are needed for further research, in terms of laser power and scan speed.

Mechanical Behavior of a Novel Precast Concrete Beam–Column Joint Using the Mortise–Tenon Connection

The construction industry has been a significant contributor to global carbon emissions. Fortunately, it is well known that precast concrete structures possess the benefit of reducing carbon emission, of which the beam–column joint plays a crucial role in resisting severe loads. Nowadays, the cast-in-place joint is mostly adopted for beam–column joint The authors declare no conflict of interests of precast concrete structures, and the building industrialization degree is insufficient. In light of this, a novel precast concrete beam–column joint using the mortise–tenon (MT) connection is proposed inspired by traditional timber structures, and the contrastive analysis of mechanical behaviors of this joint and the same-sized cast-in-place joint is conducted by the finite element method. The results indicate that the proposed MT joint has a better mechanical behavior by comparing with the corresponding cast-in-place joint as the beam–column joint. Meanwhile, the MT connection mode has the characteristics of standardized construction, in line with the concept of sustainable development, which can greatly save the construction period. This research demonstrates the feasibility of MT joints in traditional timber structures as beam–column joints in precast concrete structures, and the application of MT joints may be promoted if the size and shape of that are further optimized. Furthermore, this in turn helps research and innovation of precast building construction technology and promotes the sustainable development of the construction industry in the direction of energy conservation and environmental protection.

Experimental and Theoretical Investigation of Rotational Behavior of Straight Mortise-Tenon Joints Considering Local Compression Perpendicular to Grain

Experimental and Theoretical Investigation of Rotational Behavior of Straight Mortise-Tenon Joints Considering Local Compression Perpendicular to Grain

Shaking table tests on single-bay timber-framed wall specimens with fired brick and adobe block infills and mortise-tenon joints

In-plane uniaxial shaking table tests were carried out on full-scale single-bay timber-framed masonry wall specimens characteristic of Ottoman-period mansions in mainland Greece. The posts were connected to the sill-beam with cylindrical mortise-tenon joints. Two infills were investigated: solid fired clay bricks with lime-cement mortar and adobe blocks with earth mortar. Both specimens proved able to withstand significant base accelerations up to 1.0 g with little damage, exhibiting rocking behavior, with the post tenons lifting up from the mortises due to exceedance of friction at the contact surfaces. The earth material specimen presented higher uplift, top displacement and acceleration. A short comparison with static monotonic and cyclic tests is also presented.

Experimental study on fracture damage and seismic performance of loose through-tenon joints in ancient timber structures

A looseness is typical damage of mortise-tenon joints in ancient timber structures. Brittle fractures of loose joints are likely to occur, leading to joint failure during earthquakes. This study conducts pseudo-static tests on three groups of full-scaled through-tenon joints to examine the fracture damage and seismic behavior of the loose mortise-tenon joints and determines fracture damage modes of through-tenon joints with different looseness. It uses the acoustic emission method to measure the ring count on the tenon surface, along with each joint's critical load and critical energy release rate and then analyzes the fracture damage performance of different tenon joints. In addition, this research investigates the hysteretic and skeleton curve, stiffness degradation curve, and tenon pulling quantity of the joint under various fracture damage states. The results showed that the fracture failure mode of the through-tenon joint is a fracture in the variable cross-section and along the local tenon neck. During the loading process, the critical energy release rate initially increases and then decreases as the looseness grows. In addition, with the increase of crack mouth opening displacement (CMOD) and crack length, the bending moment of the joint firstly increases and then decreases. When the variable cross-section breaks and the tenon neck partially cracks, the joints' bending moment and stiffness reduce with increasing looseness. With the increase in local embedment compression in the lower side of the beam end and the mortise, the amount of tenon pull-out of loose joints decreases under positive and negative loading.

Application of SPO2IDA in Seismic Performance Evaluation of Ancient Timber Structures

ABSTRACT Ancient timber structures have a high cost for conducting dynamic time-history response analysis due to the presence of many nonlinear components, such as mortise-tenon joints and Dou-Gon. To enhance the efficiency of evaluating the seismic performance of ancient timber structures through dynamic analysis, a simplified dynamic response analysis method based on SPO2IDA was adopted to evaluate the seismic performance of a timber frame palace with nine-purlin in Qing Dynasty of China and the results were compared with those obtained using the traditional pushover analysis method. The results showed that there were only slight differences in the seismic response of the ancient timber structure determined by the two methods when the structure was in a nonlinear stage. During a Ⅸ degree rare earthquake, the displacement response differed by 0.004 m, while the median seismic intensity during the third level of damage limit state differed by 0.079 g. The traditional pushover analysis method may underestimate the seismic resistance of the ancient timber structure, but the SPO2IDA algorithm can better capture the uncertainty of the structural vulnerability model at different limit stages caused by ground motion input, achieving the goal of quickly evaluating the seismic performance of the ancient timber structure with acceptable accuracy.

Experimental study on seismic performance and deformation damage of loose dovetail-tenon joints in ancient timber structures

A looseness is typical damage for mortise-tenon joints in ancient timber structures. The tenon of the loose dovetail-tenon joints is prone to be pulled out, leading to joint failure in the earthquake. Hence, it is necessary to investigate the seismic performance and deformation damage of loose dovetail-tenon joints. This study conducts pseudo-static and acoustic emission (AE) tests on three full-scaled dovetail-tenon joints to determine the four stress stages of each joint, including slight damage, medium damage, severe damage, and nearly failure. It examines the hysteretic and skeleton curve, stiffness and strength degradation, energy dissipation performance, and the variation raw of the amount of tenon pulled out at each stage. The deformation damage mode, damage degree, and damage evolution equation of the joint at each stage are obtained based on the AE characteristic parameters measured at each stage. The results indicate that as the rotation angle increases, each joint's stiffness and energy dissipation capacity decrease, while the joint bending moment rises and then reduces, and the amount of tenon pulled out increases. The greater the degree of looseness, the lower the bearing capacity of each joint, and the more pronounced the degradation of stiffness and strength. At each stage, the maximum decrease of initial stiffness is 85.75%, and the maximum amount of tenon pulled out is 93 mm. The failure modes of joints are mainly tenon pulled out failure, and extrusion deformation greatly influences the tenon pulled out failure. As the degree of looseness grows, joints are more prone to severe deformation damage under large rotation angles. At the slight and medium stages, the joints primarily suffer from tensile damage of material, but at the severe damage and nearly failure stage, they mainly suffer from shear damage of material. The damage value of each joint increases with the relative stress ratio, and looseness significantly impacts the damage degree of the joint.

Study on loose damage monitoring of mortise-tenon joints in traditional wooden structures based on piezoelectric active sensing

In traditional Chinese wooden structural buildings, mortise-tenon joints are used as connection nodes. Under the erosion effects from wind and rain, such nodes are prone to aging and loosening. If they are not tracked and repaired in time, they are likely to cause structural damage when they encounter sudden loads such as earthquakes. In accordance with engineering practice, one mortise-tenon joint specimen with a penetrating straight tenon and one mortise-tenon joint specimen without a penetrating tenon were constructed. Active sensing technology based on piezoelectric ceramics was used to identify the loosening state of tenon and mortise joints. The amplitude of the piezoelectric signal, wavelet packet energy, information entropy, and damage index based on the root mean square deviation were analyzed. It was found that with the increase in loosening damage, the amplitude of the signal gradually decreases, and the information entropy gradually increases. When the damage reaches a certain extent, the changes in the monitoring signal characteristics is limited. The proposed monitoring method can be used to identify the damage state for mortise-tenon joints effectively, and the research results can provide a valuable guideline for the repair of mortise-tenon joints used in traditional wooden structures.

A Parametric Optimized Method for Three-Dimensional Corner Joints in Wooden Furniture

The three-dimensional corner joint is a type of joint in wooden furniture structures with complex parameter relationships and many constraints. Traditional furniture structure design requires repeated modifications of geometric models to determine parameter dimensions, which is inefficient and challenging and severely impacts the development of the digital design and manufacture process. Based on the ideal value range of mortise–tenon joints, this study derived a parametric optimized method of three-dimensional corner joints in wooden furniture and refined the theoretical value range of at least four main parameters: the width of the beneficial mortise (B2), the depth of the cede mortise (C1), the margin thickness from the cede tenon to the rail1 reference edge (bt1), and the margin thickness from the beneficial tenon to the rail2 reference edge (bt2). With case verification, the results show that in the axial direction of the cede tenon, the maxC1 decreased by 5.4 mm and the combination of B2,C1 reduced at least 23 kinds. In the cases of different post widths and the margin thickness from rail2’s reference edge to the post’s reference edge (Btm2), the value range and value quantity of bt2 were narrowed and decreased in various degrees. In the axial direction of the beneficial tenon, the value range and quantity of available values of the margin thickness from the cede tenon to the rail1 reference edge (bt1) decrease with decreasing margin thickness from the rail1 reference edge to the post reference edge (Btm1) when Btm1 is less than constant z. The parametric optimized method of three-dimensional corner joints in wooden furniture can effectively reduce the parameter dimensional value range, both theoretically and practically, and more refined value ranges can be obtained by setting more standard values. This method also provides ideas for the digital and standardized design of wooden furniture structures.

Lateral performance of mortise-tenon jointed frames in multi-story traditional heavy timber structures: Mechanism and quantification

This study isolated and quantified the lateral load-resisting mechanism of mortise-tenon jointed frames in multi-story traditional heavy timber structures. By decomposing the lateral performance of the mortise-tenon jointed frames, three rocking frame specimens and a moment-resisting frame specimen were half-scaled designed. Lateral resistance from timber columns and mortise-tenon joints was directly obtained by reversed cyclic loading tests, respectively, and was compared to quantify the mechanism of the mortise-tenon jointed frames in different stories. Characterized models were proposed for the lateral resistance from the columns and joints, respectively. A model-based parametric study was further conducted to indicate the influence of the column height and diameter on the mechanism of the mortise-tenon jointed frames. Test results showed the columns dominated both in the lateral load-resisting capacity and energy dissipation capacity of the frames at small drift, and the columns still contributed over 50% of those capacities before a drift of 10% with the increase of loading amplitude. The characterized models well captured the evolution features of the load–displacement curves of the tested specimens. The parametric study indicated that by increasing 30% of the column height, the lateral load contribution of the mortise-tenon joints ranged from 60% to 90% at a drift of 12%. Moreover, a decrease of 30% in the column diameter led to a significant drop in the load-resisting capacity and deformability of the columns, making the mortise-tenon joints dominate in the lateral capacity of the frames after a drift of 8%.

Influence of the axial load ratio on the mechanical behaviour of prefabricated concrete shear walls with Mortise–Tenon joints

Prefabricated concrete shear walls with mortise–tenon joints (MTJ shear walls), as innovative fully prefabricated concrete shear wall structures without extended reinforcements, can meet the development needs of the current construction industry in China. One cast-in-place concrete shear wall and four MTJ shear walls with different axial load ratios (ALRs) were tested by performing pseudostatic tests. The mechanical behaviour of the MTJ shear walls and the influence of the ALR were studied. The test results show that the construction of the mortise–tenon joint in the MTJ shear walls was reasonable and that the connection was reliable. The failure process of the MTJ shear walls was different from that of the cast-in-place concrete shear wall. Vertical cracks formed along the bottom of the transverse grooves, which weakened the integrity of the MTJ shear wall and contributed to improving the deformability. The damage to the MTJ shear walls was mainly concentrated around the mortise–tenon joints, resulting in a reduction in the concrete crushing area at the root of the cast-in-place concrete boundary elements (CBEs) on both sides of the shear wall. With an increase in the ALR, the yield load and peak load of the MTJ shear wall gradually increased, but the displacement ductility coefficient decreased. However, when the test ALR was 0.30, the displacement ductility coefficient of the corresponding MTJ shear wall still reached 3.73, exhibiting good deformability. Reasonable numerical analysis models were established with ABAQUS to systematically analyse the influence of the ALR on the mechanical behaviour of MTJ shear walls. The ALR limit value of the MTJ shear wall was recommended to be 0.45.

Seismic behavior and theoretical analysis of mortise–tenon joints reinforced with steel components

Wood structures have been vigorously popularized and developed because they have low carbon emissions and acceptable earthquake resistance. To solve the general pull-out failure of mortise–tenon joints (MTJs) under earthquake loads, reinforcement techniques, such as steel strip plate (SSP), hollow rectangular steel plate (HRSP), U-shape steel plate (USP), and T-shape steel plate (TSP) methods, have been proposed. Low cyclic loading tests were conducted on five joints to investigate the effect of reinforcement methods on the seismic behavior of MTJs. Furthermore, the peak bearing capacity of reinforced MTJs was theoretically analyzed based on European, American, and Chinese specifications; the calculations were compared with the test results. To verify the accuracy of the theoretical analysis, ABAQUS software, a finite element simulation application, was used. The test results show that the failure modes of joints with or without reinforcements are tenon pull-out, self-tapping screw pull-out, and shear failure. Moreover, the USP-reinforced MTJ exhibited the best seismic performance, followed by the MTJs reinforced with TSP, HRSP, and SSP. The theoretical calculation and test results are in good agreement. The simulation results indicate that the proposed calculation methods can accurately predict the peak bearing capacity of steel-reinforced MTJs.

Shear Force Capacities of H-Type Furniture Joints Constructed of Various Heat-Treated Wood Species

The aim of this study was to investigate the effect of wood species, heat treatment, adhesive type and joint technique on shear force capacity of H-type furniture joints. For this purpose, an experimental design that consisted of 3 wood species, 2 treatment processes (untreated, heat-treated), 2 adhesive types (polyurethane (PUR), polyvinyl acetate (PVAc)) and 2 joint techniques (dowel, mortise-tenon (MT)) and 5 replications for each group were prepared, and accordingly, a total of 120 specimens were tested under static shear loads. Siberian pine (Pinus sibirica), Iroko (Chlorophora excelsa), and common ash (Fraxinus excelsior), which are commonly used in furniture constructions, were used as wood species. In general, iroko showed the highest shear force capacity between the wood species. The specimens constructed of heat-treated wood species showed lower shear force capacity by approximately 15 % in comparison to the same untreated specimens. MT joints showed better performance than dowel joints higher by approximately 21 %. PVAc adhesive gave higher values than PU adhesive by around 5 %. According to the results of four-way interactions, highest shear force capacities of H-type joints were obtained from “Common ash-PVAc-MT” combination in groups of untreated specimens and from “Iroko-PU-MT” combination in groups of heat-treated specimens.