体内预应力胶合木梁抗弯承载能力研究

Study on Flexural Capacity of Internal Prestressed Glulam Beams

为研究体内预应力胶合木梁的抗弯承载能力,结合国内外相关试验研究结论,基于Bazan的木材本构关系模型、平截面假定和极限应变分析方法,提出了受拉破坏模式和受压破坏模式的判别方法,建立了构件极限承载能力公式,算例表明,本文给出的公式计算结果与试验值吻合较好;考察了极限承载能力与有效张拉力的关系,研究表明,有效张拉力是影响胶合木梁受弯破坏模式的决定性因素,且木材顺纹受压区下降段的力学性能参数对极限承载能力与有效张拉力之间的关系影响很大;定量地分析了受拉破坏模式和受压破坏模式下,承载能力极限状态下的预应力筋内力均与有效张拉力近似呈线性关系的性质;分析了预应力筋有效张拉力的上、下限值,分别对应:承载能力极限状态下预应力筋刚好屈服、受拉破坏与受压破坏同时发生,并给出了上、下限值解析解的表达形式.

To study the flexural capacity of internal prestressed glulam beams,the relevant conclusions of experimental research at home and abroad were summarized,the methods to predict the failure mode and the formula of the flexural capacity were proposed based on Bazan＇s constitutive relation model,the planesection assumption and the limit strain analysis method.The computation examples demonstrated that the calculated results according to the formula were in reasonable agreement with the experimental data.The relationship between the flexural capacity and the effective tensioning force was studied,and it showed that the effective tensioning force could determine the failure mode,and the mechanical property parameters of the compressive zone were the key influencing factors of the relationship.The internal force of the tendons under tensile failure mode or compression failure mode was approximately linear with the effective tensioning force.The upper and lower limit of the effective tensioning force were defined,which indicates that the tendons yield when the failure happens,and tension failure and compression failure occur simultaneously.The analytical solutions of the upper and lower limit were also provided.