A novel approach is introduced for reinforcing mortise-tenon joints in timber structures using knee-brace-type viscoelastic dampers (KBVDs). Mechanical property tests were conducted systematically to evaluate the performance of the KBVDs. Quasi-static cyclic loading tests were conducted on joints reinforced using various strategies, including unilateral reinforcement (with and without a pin) and bilateral reinforcement. The hysteresis behavior, stiffness degradation, energy dissipation, tenon pull-out, and overall performance enhancement of the specimens were analyzed. Results indicate that KBVDs exhibit exceptional hysteresis and fatigue performance. All three reinforcement strategies improved the load-bearing capacity, stiffness, and energy dissipation of the joints to varying degrees compared to the unreinforced counterparts, with bilateral reinforcement yielding the most pronounced enhancement, increasing ultimate capacity by up to 562%, late-stage stiffness by 493%, and cumulative energy dissipation by 437%. Further quantitative comparison among the three strategies shows that the addition of a central pin to the unilateral configuration has a negligible effect on force-based metrics, with capacity, stiffness, and energy dissipation ratios between the pinned and unpinned configurations ranging from 0.94 to 1.33; its primary function is to mechanically restrain tenon pull-out. Bilateral reinforcement, in contrast, outperformed the pinned unilateral configuration by factors of 1.6-3.1 in ultimate capacity, 1.6-3.3 in late-stage stiffness, and 1.6-4.5 in cumulative energy dissipation, while providing equivalent tenon pull-out control. Bilateral reinforcement with KBVDs is therefore recommended as the preferred retrofitting strategy, with pinned unilateral reinforcement as a viable alternative under spatial constraints. Unilateral reinforcement without a pin is inadvisable owing to the aggravated tenon pull-out risk.

This study proposes a rotational viscoelastic damper (RVED), installed on the side faces of traditional timber mortise-tenon joints, to dissipate seismic energy via torsional shear deformation activated by joint rotation. Two RVED configurations with different material compositions were fabricated and examined through damper characterization tests and quasi-static cyclic loading tests on bare and RVED-retrofitted T-shaped joints. Key seismic performance indices were evaluated and compared, and an analytical moment-rotation (M-theta) model for the strengthened joints was established based on the experimental observations. The results indicate that the RVEDs exhibit stable hysteretic responses and good fatigue resistance. The bare joints showed pronounced pinching, limited moment capacity, substantial stiffness degradation, and only moderate energy dissipation at large deformations. By contrast, the strengthened joints developed markedly fuller hysteresis loops: the average stiffness increased to 2.54 and 4.55 times that of the bare joints (ZQ1 and ZQ2, respectively), while the final cumulative dissipated energy increased by factors of 2.42 and 4.34, respectively. The proposed M-theta model predicts the experimentally observed peak moments with good accuracy, providing a practical analytical basis for RVEDbased retrofitting of traditional timber structures.

This study investigated the seismic performance of Chuandou-type timber structure buildings intended for seismic fortification in a high-intensity zone. An earthquake simulation shaking-table test was conducted on a two-layer Chuandou-type structure constructed in Yunnan, China. The El Centro, Kobe, and artificial waves were used as input excitations. The natural frequency, stiffness, acceleration response, and displacement response to the earthquake events were determined. The experimental results indicate that as the acceleration intensity of the earthquake increases, the natural frequency and stiffness of the model structure decrease. The acceleration amplification coefficient of each layer varied from 0.47 to 1.95. The energy dissipation of column foot slip, mortise-tenon joint friction and extrusion were visible, and the dynamic amplification coefficient of the first layer was less than one except for Kobe wave excitation. When the input peak acceleration is 0.63 or 0.95 g, the model shocks violently and exhibits a spectacular whiplash effect, with the model's maximum inter-story drifts being 1/23 and 1/26, respectively. However, the model did not tilt or collapse, which displays that the Chuandou-type structure had an overall good deformation and self-centering ability. Additionally, it satisfies the standards of the Chinese Code for Seismic Design of Buildings (GB2011-2010).

In order to investigate the seismic performance of dovetail mortise-tenon joints involving lateral tightness between mortise and tenon, three full-scale mortise-tenon joints were fabricated as a prototype of the "one seal" traditional timber structure in southwestern China. Based on experiments of three specimens under pseudo-static test, the failure process of the specimens was observed and analyzed, and the hysteresis, skeleton, energy dissipation and stiffness degradation curves were obtained. Additionally,The hysteretic behavior of dovetail mortise-tenon joints with different lateral tightness was simulated using the Pinching4 material model in OpenSees, and a multi-objective optimization algorithm(NSGA-II)was employed to identify the model parameters.The results indicate that the lateral tightness significantly influenced joint energy dissipation, ultimate bearing capacity, initial stiffness, and ductility. Specifically, the brittle behavior becomes more pronounced as the tenon gets tighter to the mortise. The area of the hysteresis loop, ultimate bearing capacity, and initial stiffness of the joints with lateral gaps gradually decreased as the damaged degree increased. Furthermore, the size relationships of the equivalent viscous damping coefficient were as follows: moderate joint > tight joint > loose joint. The minimum limit angle for all joint models exceeded 0.12 rad.Compared to the test results, the pinching4 material model accurately characterizes the strength degradation,unloading stiffness degradation, pinching behaviour and asymmetry of the hysteretic curve. The proposed parameter identification procedure is verified to be applicable in the field of traditional dovetail mortise-tenon joints. The test results of bending capacity and energy dissipation of mortise and tenon joints were compared with the simulated values with an error of less than 5 %.

The precise determination of the critical force for frame structures usually necessitates iteratively solving intricate transcendental characteristic equations. The energy method can approximately calculate the critical force, but it is very difficult to establish and solve the energy equation. In the present study, a model employing a spring-pendulum column is introduced to delineate the internal and external stiffness of a structure. The formula for the separated column's internal and external stiffness is formulated. By exploiting the principle that the internal stiffness equals the external stiffness during frame instability, a practical formula for directly computing the critical bearing capacity of the original frame structure is derived. This methodology significantly streamlines the resolution of the critical force. The formula is an algebraic equation adept at accommodating the story-to-story support effect and the inter-column support effect within the same story. Compared to finite element analysis, this method exhibits excellent precision and accuracy, rendering it suitable for engineering design and theoretical calculations. To summarize, this paper presents a lucid concept and a practical calculation formula for determining the critical force of frame structures. The proposed method streamlines the solution process and resolves several shortcomings of existing approaches, thus making a valuable contribution to the field.

A mortar overlay on damaged adobe masonry is employed for its load carrying capacity improvement and low skill requirement. Nevertheless, delamination between the adobe wall and mortar has been commonly observed due to bonding failure. Physical enhancement (groove, shear dowel, and wire mesh) and chemical enhancement (a novel biological and traditional Chinese binder, sticky rice pulp, SRP) are carried out to enhance the bonding between mortar and adobe. The high-moisture adsorption mortar is also utilized to alleviate water accumulation resulting from the application of mortar on earthen buildings. Four adobe walls with different retrofitting methods are subjected to in-plane lateral cyclic loading tests to analyse the failure mode, hysteretic load-displacement response, skeleton curve, ductility behaviour, energy dissipation and stiffness degradation. It indicates that the retrofitting effectiveness of adobe walls coated only with mortars is limited, as their peak load increases are comparatively modest compared to other retrofit wall systems. However, employing additional bonding enhancement methods significantly enhances the peak load capacity. Specifically, a combination of physical and chemical enhancements results in a remarkable 114% increase on the positive side and an astonishing 500.1% increase on the negative side.

This paper proposes the utilization of support-type viscoelastic dampers to enhance the seismic performance of traditional timber mortise-tenon joints. Four viscoelastic dampers and three Tshaped mortise-tenon joints were manufactured, with two dampers designated for performance testing and the remaining two dampers installed on the mortise-tenon joints. Subsequently, cyclic loading tests were carried out on the reinforced mortise-tenon joints and two control mortisetenon joints. A comparative analysis was conducted on the changes in the moment-rotation hysteresis curve, skeleton curve, stiffness, and energy dissipation capacity before and after joint reinforcement. Based on the observed deformation characteristics of the joints during the tests, a theoretical moment-rotation model for the reinforced mortise-tenon joint was derived and juxtaposed with the experimental results. The study demonstrates that the viscoelastic dampers exhibit stable stiffness and exceptional energy dissipation under cyclic loading. In contrast, the stiffness of the mortise-tenon joints from the control group degrades significantly with increasing rotational deformation, whereas the joints with dampers maintain relatively stable stiffness. The installation of dampers led to a remarkable improvement, with the maximum moment-bearing capacity and average stiffness increasing by 2.3 times and 1.5 times, respectively. The total energy dissipation of the reinforced joints under the same loading reached 2.69 kN & sdot;m & sdot;rad, representing a 1.8-fold increase compared to the control joints. The calculated results of the theoretical moment-rotation model for the reinforced joints align well with the experimental results, providing a robust theoretical foundation for the application of support-type viscoelastic dampers in strengthening mortise-tenon joints.

To study the aseismic performance after the reinforcement of the mortise-tenon joints of folk houses with traditional Chuan-Dou style wood structure and their steel plate, test specimens of joints—two for Tou mortise-tenon joints, two for Ban mortise-tenon joints, and two for dovetail mortise-tenon joints—were fabricated out of hemlock, and steel plates were utilized to reinforce one of the joint specimens of each type on the middle part of the mortise-tenon joint. By carrying out pseudo-static tests on the joints and building ABAQUS numerical model; the position where the mortise-tenon joints were to be reinforced by the steel plates was optimized for a comparative analysis into the test results on reinforced and unreinforced mortise-tenon joints and the numerically simulated bending moment-turning angle hysteresis curve, skeleton curve, energy-dissipating capacity, and rigidity degeneration curves. The results showed the following: the pulling-out phenomenon of tenons was severe, and the aseismic performance of Tou tenons was superior to Ban tenons and dovetail tenons; reinforcing the middle part of mortise-tenon joints with steel plates could effectively reduce the pulling-out amount of joints and promote the aseismic performance of mortise-tenon joints but have an insignificant promotive effect for the bearing capacity of Tou mortise-tenon joints; the aseismic performance was improved significantly after the flat steel strip reinforced position was moved to the upper and lower ends of mortise-tenon joints, with the ultimate bearing capacities being 1.5∼2.4 times that on the middle part of flat steel strip reinforced joints.

为研究高烈度设防区大底盘双塔高位连体减震结构的抗震性能,制作了缩尺比1/36的模型结构,分别对设置阻尼器或不设置阻尼器的模型结构(分别简称"减震结构""非减震结构")进行振动台试验,对比分析连体结构的动力特性、破坏特征、加速度、位移和应变响应.结果表明:8度多遇地震作用下,模型结构未发生破坏,基本为弹性状态;随地震作用的增大,模型结构的损伤逐渐累积,加速度放大系数逐渐减小,连接体上部和裙房附近的主塔楼层及副塔中、下部楼层的剪力墙连梁、框架梁端、框架柱端为结构主要损伤部位;罕遇地震作用下,主桁架下弦杆与主塔框架柱连接节点处混凝土表面出现细微裂缝,但连接体未发生明显损伤;连接体以上结构鞭梢效应显著,其楼层加速度、位移及扭转等地震响应增大明显;减震结构中黏滞阻尼器滞回曲线饱满,产生了良好的减震效果;相较于非减震结构,减震结构的层间位移角和顶部扭转角均有不同程度的降低,罕遇地震作用下最大减震率分别为94.6％和92.1％,减震结构层间位移角未超过规范限值,满足"小震不坏"和"大震不倒"的抗震设防要求;应变分析结果表明,设置阻尼器后,连体部位的应力改善效果优于结构底部的,建议适当提高结构底部构件的延性.

为实现最大限度发挥减震结构中阻尼器的耗能效率,本文研究了黏滞阻尼器耗能占比的计算方法及其影响因素.针对单自由度结构体系,基于能量分析法,推导并得出简谐激励下结构弹性和弹塑性状态时黏滞阻尼器耗能比的计算公式,利用有限元软件验证计算公式的准确性,并对附加黏滞阻尼器的SDOF体系进行能量时程分析.研究结果表明:阻尼器耗能比与频率比、阻尼系数、阻尼指数以及延性系数等参数相关;在地震作用下,将弹性结构的阻尼器出力之和与层间剪力比作为下限,附加阻尼比作为上限,给出阻尼器耗能比与阻尼参数的取值范围,弹塑性阶段阻尼器出力与结构层屈服力比远低于规范所规定的60％.

Damaged adobe masonry is essential to retrofit not only for continued use by less developed populations but also for historical preservation and vernacular landmark maintenance. Coating mortar on adobe can greatly improve the static load-carrying capacity of adobe masonry Wallette. Four retrofitting methods are carried out to enhance the cooperation of mortar and adobe; these four methods focus on the factors of roughness, shear dowel, and mesh size and a novel biological and traditional Chinese binder, sticky rice pulp. The mortar coating with the four bonding enhancement methods can greatly increase both the compressive and lateral load-carrying capacities, with a maximum improvement of 177 and 743%, respectively. The bonding strength has a negative effect on the compressive load-carrying capacity; on the other hand, it has a positive effect on the lateral load-carrying capacity. A range analysis is also carried out, which shows that the shear dowel depth has the greatest effect on both load situations, followed by the wire mesh size.

For the study of the mechanical properties of straight-tenon joints in traditional wooden structures, three specimens of T-shaped straight-tenon joints were made according to actual structures and subjected to reciprocating loading tests. The variation rules of different seismic performance indexes such as moment-rotation hysteresis curve, skeleton curve, stiffness, and energy dissipation capacity of the specimens were analyzed through tests. Based on the geometric deformation and static equilibrium conditions, the moment-rotation theoretical model of straight-tenon joints is derived and compared with the experimental results. The studies show that the hysteresis curve of joints under reciprocating loading consists of four stages: ascending, stress relaxation, descending, and sliding. The moment capacity of joints increases gradually with the rotational deformation, but the internal gap of the joints increases synchronously, resulting in a serious attenuation of the stiffness. Tenon and mortise plastic extrusion deformation and friction can dissipate energy, as the rotational deformation increases energy consumption, while the hysteresis loop “pinch” effect is more serious, and the equivalent viscous damping coefficient is gradually reduced. The prediction results of the joint moment-rotation theoretical model are closer to the experimental results, which can provide a theoretical basis for the overall seismic analysis of traditional wooden structures.

Looseness, deformation, and tenon pulled in the mortise-tenon joint constitute the primary causes of failure in traditional Chinese timber structure building. However, the introduction of the joint damper technology and installation of the fan-shaped shear damper at the mortise-tenon joints of traditional wooden structure solves these issues. Herein, we explored the strengthening effect of dovetail mortise-tenon joints with dampers. We designed six dovetail mortise-tenon joint models, three without dampers, and the other three were installed with dampers. Using the low cycle repeated loading test, we examined the hysteretic response, skeleton curve, stiffness degradation curve, and equivalent viscous damping coefficient curves of the six test models. Consequently, we established that the joint damper effectively controls the joint tenon pulled problem and enhances energy dissipation, strength, and rotational stiffness. Besides, the ultimate bearing capacity of the damper models was nearly four-fold that of models without dampers.

为研究钢板阻尼器加固木结构直透榫节点的抗震性能,对加固前后的试件开展拟静力试验及数值模拟.结果表明:采用钢板阻尼器加固节点后,试件节点处应力明显降低,主要应力集中在钢板核心处,滞回曲线的捏缩效应明显降低,榫卯节点的承载力和刚度都得到有效提升;试验结果与模拟结果较为吻合.

Foamed cement fly ash is a new type of lightweight construction material that can be combined with a light steel frame to form light-steel skeleton–cement–fly ash foam wallboard (LSSCFAFW). The research on the axial compressive performance of light steel and light concrete composite wallboard is relatively limited. Four pieces of LSSCFAFWs were manufactured, and the impact of stand column quantity and various filler parameters on the LSSCFAFW was investigated. The failure mode of the wallboard and the influence of different parameter variables on its axial compressive performance were obtained through experiments. Moreover, the test results indicated essentially the same damage patterns in terms of stand-column buckling, filler crushing, and self-tapping screw failure. The addition of polypropylene fiber to this wallboard can prevent filler from falling off. The axial compressive performance of the LSSCFAFW demonstrates a direct proportion with the number of columns and cement content, improving as the number of stand columns and the cement content increase. However, the addition of polypropylene fiber to the filler has a minimal effect on the axial compressive performance of this wallboard. Compared to the control group, increasing the number of stand columns, adding 0.4% polypropylene fibers, and increasing the cement dosage to 50% improved the ultimate bearing capacity of the wallboards by 12%, 8%, and 56% respectively. The result of this study can provide references for the research and application of light steel frame to form LSSCFAFW.

In order to study the seismic performance of a museum adopting a measure of seismic isolation and shock absorption, a 1/30 scale model of the structure with rubber isolation bearings beneathe column bottoms of ground floors and buckling-restrainted braces in the upper structure was conducted on a shaking table for earthquake simulation tests. Experimental research showed that subjected to various levels of earthquakes, the combined seismic isolation and shock absorption structure was only slightly damaged, the first of translation natural vibration frequency in the Y-direction was reduced by 9.1% subjected to the fortification earthquake, and the first torsional frequency reduced by 6.1% subjected to the rare earthquake. The acceleration amplification factor was 0.45 in the isolation storey, and the upper structure was also less than 1.0. The energy consumption performance of isolation bearings became better and better with the increase of earthquake intensities. From the energy consumption of only about 4 kN·mm under frequent earthquakes to the maximum energy consumption of about 426 kN·mm under rare earthquake, the combined measure for the structure achieved the expected shock absorption goal well.

高烈度区异形柱框架节点核心区抗剪不足,节点区增配桁架式型钢钢骨能较好解决异形柱节点核心区薄弱问题.为充分发挥型钢钢骨作用,并促进其推广应用,应优化型钢钢骨构造.首先开展十字形截面异形柱节点拟静力试验,对比分析节点区增配桁架式型钢钢骨对抗震性能的影响,然后利用有限元软件ABAQUS建立 9 个十字形异形柱节点分析模型,优化分析型钢钢骨的肢板长度、厚度,获得节点破坏形式、骨架曲线、承载力、延性、刚度、耗能能力等性能指标.结果表明,节点区增配桁架式型钢钢骨的异形柱框架节点承载力与钢骨肢板伸入梁内长度成正比,但肢板伸入梁内超 1 倍梁高时,钢骨对节点承载力的提升作用开始减弱,控制肢板厚度≥5mm基本可实现外移梁端塑性铰,而 15mm厚度的肢板会导致节点延性过低.综上,节点区增配桁架式型钢钢骨建议肢板厚度为 10mm,肢板伸入梁内 1 倍梁高.

Based on the fact that the development of nonlinear solid mechanics has been closely integrated with the material microstructure, this paper derived the vertical stress satisfying the harmonic function at any point from the super-elastic constitutive equation of the rubber; further, the uniaxial equivalent elastic modulus \begin{document}${E_c}$\end{document} and the pure bending equivalent bending stiffness \begin{document}${E_c}Is$\end{document} of the single-layer rubber were obtained from the vertical stress integration. Then the seismic isolation rubber bearing was equivalent to a homogeneous body conforming to \begin{document}${E_c}$\end{document} and \begin{document}${E_c}Is$\end{document} , and the partial differential equilibrium equation macroscopically reflecting the degree of shear and bending deformation of the rubber bearing was established in the simultaneous action of two external load, and its general solution was obtained. The difficulties of the geometrical non-uniformity of large shear deformation of rubber support were solved in the vertical and horizontal loads. On this basis, a full-scale seismic isolation test of rubber bearing for compression and shear experiment was carried out. According to the experimental shear modulus \begin{document}$(G)$\end{document} and horizontal shear strain \begin{document}$(\gamma )$\end{document} curves, the experimental curves of the horizontal thrust \begin{document}$\left( {{F_H}} \right)$\end{document} and \begin{document}$\gamma $\end{document} of the bearing were obtained. It was almost completely overlapped with the theoretical curve. Therefore by introducing the material nonlinearity into the above differential equilibrium equation, the double nonlinear problem of large shear deformation of the superelastic rubber bearing was solved. Following the above answers, the internal force distribution law of the rubber bearing was obtained, which has a clear guiding significance for judging the weak part of the bearing. Subsequently, the comparative analysis of two more important characteristics (shear strain correlation and axial pressure correlation) of the rubber bearing was carried out, which can provide practical application value for engineering. Finally, the horizontal thrust and displacement of the support can also be obtained through the sensor monitoring the internal stress of the support, achieving the health monitoring of the isolated building during the earthquake.

A single mortar layer on adobe wall has a limited enhancementA sticky rice pulp surface treatment on adobe wall benefits the lateral cyclic loading behaviourThe compatibility of shear dowel, groove, wire mesh and SRP surface treatment with mortar is efficient for adobe masonry retrofitting

为研究不同加固措施对木结构榫卯节点抗震性能的影响,参照西南地区传统木结构典型榫卯节点做法,制作透榫、半榫和燕尾榫3类共5组榫卯节点试件开展节点拟静力试验,其中4组分别采用扒钉、钢板和木条(两组)加固.对比研究加固与非加固节点试件的破坏形态、滞回曲线、骨架曲线、节点拔榫量和耗能能力等抗震性能参数.结果 表明:未加固榫卯节点的主要破坏形态是榫头卯口挤压开裂、榫头拔出,加固节点主要以扒钉断裂、钢板弯扭屈服和木条断裂形态而破坏;所有加固措施均能有效提升节点承载力和降低节点拔榫量,加固节点拔榫量降低比例均超过5％;与扒钉、钢板加固相比,采用木条加固对节点承载力提升效果最为显著,加固后,半榫和燕尾榫节点负向承载力提高超过10倍.同时,木条加固半榫节点的耗能能力提升超过2.6倍,扒钉、钢板加固节点也能明显提升其耗能能力.