国产速生树种落叶松胶合木梁疲劳性能研究

China has the world's most abundant resources of plantation timber, among which about 70% is used for manufacturing furniture and interior decoration etc. The percentage is very small in the construction industry whose demand of material is huge, especially in the field of large-span spatial engineering structural materials with high additional value, its application is almost completely blank. In view of the state that preliminary study focuses on static performance of the wooden engineering component, instead, dynamic performance of which lacks seriously. The key studies of the fatigue properties of the domestic fast-growing larch glulam beams are carried out. Analysis of the curve of the fatigue characteristic for glulam beams are made and the finite element model is built. Meanwhile the method of verification and correction for the result are used to verify by experiment and theoretical analysis results. The influence rule of the parameters such as the stress amplitude, stress ratio and moisture content are explored. This project is aimed at obtaining the fatigue properties of the domestic fast-growing larch glulam beams, grasping the fatigue failure pattern and failure mechanism. Based on the model of Damaged Viscoelastic Materials(DVM), the rule for the initiation and development of fatigue crack are analyzed. The Stiffness degradation equation for fatigue is deduced, and the model of residual strength is set up, meanwhile a method of predicting the fatigue life of larch glulam beams is presented. The theory and experiment for the widespread use in the engineering and enacting relevant technical standards of the domestic fast-growing larch glulam beams are provided.

我国拥有世界上最丰富的人工林木材资源，约70%被用于家具制造和室内装饰等方面，而在材料需求量巨大的建筑业当中所占比例极小，特别是在大跨空间工程结构材料领域的应用几乎空白。针对前期研究主要集中于木质工程构件静力性能方面而关动力性能研究严重缺乏的现状，重点开展国产速生树种落叶松胶合木梁的疲劳性能研究。分析胶合木梁疲劳特性曲线，建立疲劳荷载作用下的有限元模型，并利用试验及理论分析结果加以验证和修正，探寻应力幅、应力比、含水率等参数对疲劳性能的影响规律。本项目旨在通过研究获得国产速生树种落叶松胶合木梁的疲劳特性，掌握其疲劳破坏形态和破坏机理，基于损伤粘弹性材料（DVM）模型，分析疲劳裂纹的萌生及发展规律，推导出疲劳刚度退化方程，并建立剩余强度模型，提出一种落叶松胶合木梁疲劳寿命预测方法，为国产速生树种落叶松胶合木梁在工程中的广泛应用及相关技术标准的制定提供理论和试验依据。

在林木产业优化升级、低碳环保建筑的应用背景下，现代木结构工程材在市场需求巨大的建筑业中占比极小，特别是在大跨空间工程结构材料领域。开展胶合木梁的疲劳性能研究将会加快拓展现代木结构在工程领域的应用，符合国家的可持续发展政策。.本项目主要针对胶合木梁在疲劳荷载下的受力性能及疲劳寿命等科学问题开展系列研究主要研究内容：1）获得国产速生树种落叶松胶合木梁的疲劳特性，掌握其疲劳破坏形态和破坏机理；2）基于损伤粘弹性材料（DVM）模型，分析疲劳裂纹的萌生及发展规律；3）推导出疲劳刚度退化方程，并建立剩余强度模型，提出一种落叶松胶合木梁疲劳寿命预测方法；4）建立有效可靠的疲劳有限元模型对疲劳影响因素进行参数分析。.本项目研究了落叶松清材的力学性能、胶合木梁的受弯性能、等幅疲劳性能及变幅疲劳性能，并提出了疲劳寿命预测方法，建立了有限元模型对比分析验证，从而掌握胶合木梁疲劳性能的基本数据和基本理论方法，为胶合木梁的受弯设计和疲劳性能设计提供了理论参考和数据支持。本项目课题组共发表核心以上期刊论文8篇，编制国家标准1项，申请专利1项，参加国内外学术会议5次以上（含主办会议1次）；培养博士研究生3名，培养硕士研究生4名；项目研究成果已应用在张花高速张家界服务区现代木结构人行天桥上。.通过本项目的研究，将为国产速生树种落叶松胶合木梁在工程中的广泛应用及相关技术标准的制定提供理论和试验依据。