古建筑木结构榫卯节点力学性能分析及精细化数值模拟

发布时间：2018-06-12 23:38

本文选题：古建筑木结构 + 榫卯节点　；参考：《西安建筑科技大学》2016年硕士论文

【摘要】：中国古建筑木结构是世界建筑体系中一独立的系统,自其产生、演变以至于发展成熟,已有近七千年的历史。这类建筑的突出特点是以木构架承重(墙体并不承载,只起到空间分隔与建筑保温作用),构件间采用榫卯连接。由于榫卯节点具有优良的耗能减震性能,遂使得中国木构古建筑单体,较之其它体系的古建筑而言,具有更好的抗震特性。然而由于其所用材料木材的材性十分复杂以及节点的传力机理不明确,故从材料特性、试验研究以及数值模拟的角度探究其对整个古建筑木结构抗震性能的影响十分必要!本论文主要研究工作如下—以西安永宁门箭楼为原型,遵照清工部《工程做法则例》的规程,制作了3榀缩尺比为1：6的直榫节点木构架模型,通过水平低周反复荷载试验和直榫节点的受力机理分析,研究了木构架的破坏特征和滞回性能,揭示了古建筑木结构的破坏主要由于榫卯节点的榫头与卯口间相互挤压产生累积塑性变形,最终榫头拔出致其整个结构功能丧失；基于榫卯节点模型在水平荷载往复作用下拟静力试验的弯矩一转角滞回曲线和骨架曲线,并根据试验模型与原结构之间的相似关系,反推木构架原型的抗弯承载力、刚度,探究其对整个结构抗震性能的影响。鉴于已有文献对木材强度准则的评估存在不足,总结了目前常用的木材强度准则,结合439个不同加载比例和不同木纹角度的云杉双轴样本试验,从统计分析的角度,利用MATLAB数学软件进行编程计算,对木材常用的11种强度准则的偏轴和双轴强度预测能力进行了客观评估分析。结果表明：综合考虑强度准则的适用性和实用性,主应力相互作用系数F12=0的Tsai-Wu准则预测能力最好。通过对木材物理力学性能和强度准则的深入研究,考虑木材顺纹方向和横纹方向具有不同的强度,以及同一方向的拉、压强度也不相同的特性,根据本文研究结果,采用Tsai-Wu准则来描述木材在三维应力空间的屈服特性；基于ABAQUS/Explicit有限元软件平台,利用Fortran语言对用户材料子程序(VUMAT)接口进行二次开发,编制了木材正交各向理想异性弹塑性本构子程序,为实现精细化的榫卯节点木构架三维实体模型分析提供理论依据。接入在ABAQUS/Explicit平台进行二次开发编写木材正交各向理想异性弹塑性本构子程序(VUMAT),建立考虑榫头和卯口之间摩擦接触特性的榫卯节点木构架三维实体模型,研究其在拟静力反复荷载作用下的力学特性,得到弯矩一转角滞回曲线和骨架曲线,并结合本课题组的试验研究结果对数值模型进行验证分析,证明数值模型的可行性。
[Abstract]:The wooden structure of ancient Chinese architecture is an independent system in the world architecture system. It has a history of nearly 7,000 years since its emergence, evolution and development. The outstanding feature of this kind of building is that it is supported by wood frame (the wall is not loaded, it only acts as space separation and building insulation, and the components are connected with each other with tenon and joint). Because of the excellent energy dissipation and seismic absorption performance of the tenon joint, the ancient wooden structure in China has better seismic characteristics than the ancient buildings with other systems. However, the timber properties of the materials used are very complex and the transmission mechanism of the joints is not clear. Therefore, it is necessary to explore the impact of the material characteristics, experimental research and numerical simulation on the seismic performance of the whole ancient building wood structure. The main research work of this thesis is as follows: taking the Yongning Gate Arrow Building in Xi'an as the prototype, according to the rules of the Code of Engineering practice of the Ministry of Qing Dynasty, three straight tenon joint wood frame models with a scale ratio of 1:6 have been made. The failure characteristics and hysteretic behavior of wood frame are studied by horizontal low cycle repeated load test and mechanical analysis of straight tenon joints. It is revealed that the damage of the ancient building wood structure is mainly due to the cumulative plastic deformation caused by the joint of tenon and joint squeezing each other, and the function of the whole structure is lost as a result of the tenon pull-out. Based on the hysteretic curve of moment angle and skeleton curve of pseudostatic test under horizontal load, and according to the similar relationship between the test model and the original structure, the bending bearing capacity and stiffness of the prototype of push-wood frame are analyzed. The effect on the seismic performance of the whole structure is studied. In view of the deficiency of the evaluation of wood strength criterion in the existing literature, the commonly used wood strength criteria are summarized. Combined with 439 biaxial samples of spruce with different loading ratios and different wood grain angles, the paper analyzes the results from the point of view of statistical analysis. By using MATLAB mathematical software, the prediction ability of biaxial and biaxial strength of 11 commonly used wood strength criteria was evaluated and analyzed objectively. The results show that the Tsai-Wu criterion with the principal stress interaction coefficient F120 has the best prediction ability considering the applicability and practicability of the strength criterion. Through the in-depth study of the physical and mechanical properties and strength criteria of wood, considering the different strength of wood along the direction of grain and transverse direction, as well as the different characteristics of tensile strength and compression strength in the same direction, according to the results of this paper, Tsai-Wu criterion is used to describe the yield characteristics of wood in three-dimensional stress space, and based on Abaqus / explicit finite element software platform, Fortran language is used to develop the interface of user material subprogram VUMATT. An orthotropic ideal elastoplastic constitutive subprogram of wood is compiled, which provides a theoretical basis for the precise analysis of the three-dimensional solid model of wood frame with tenon and joint. Using the second development of Abaqus / explicit platform to compile the orthotropic ideal anisotropic elastoplastic constitutive subprogram VUMATT, a three-dimensional solid model of tenon and joint wood frame considering the frictional contact between tenon and joint is established. The mechanical properties of the model under quasi-static repeated load are studied, and the torque-angle hysteretic curve and skeleton curve are obtained. The numerical model is verified and analyzed with the experimental results of our research group, and the feasibility of the numerical model is proved.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU366.2

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