【作者】 李霞镇；

【导师】 任海青；

【作者基本信息】 中国林业科学研究院 ， 木材科学与技术， 2013， 博士

【摘要】 节点连接是竹木结构设计的关键，整体建筑结构的破坏大多都起源于节点连接的失效或破坏。在各类金属连接件中，螺栓连接具有简洁、安全可靠、使用方便等优点，随着现代竹结构的发展，螺栓连接已经被广泛应用。目前国内外对重组竹螺栓连接方面的报道甚少，故深入研究重组竹螺栓连接性能，对改善螺栓连接的安全性和可靠性都具有重要作用，也可为螺栓连接的进一步推广提供理论基础。本研究以毛竹基重组竹为试验材料，着重于研究重组竹螺栓连接节点特性，分析各因素对销槽承压、螺栓连接节点承载性能的影响，观察破坏模式，探究破坏机理；此外，评价了现行木材螺栓连接计算公式对重组竹螺栓连接承载性能预测的适用性；最后以竹材本身特性为基础，推导了适合于重组竹销槽承压强度、螺栓连接承载力的理论计算公式，为螺栓连接在现代竹结构中的应用提供一定的参考，也为竹结构用螺栓连接性能的改善、新型竹结构连接件的开发，提供可靠的理论依据。本论文的主要研究结果归纳如下：1.重组竹材料密度均一、力学强度高且稳定，完全能满足结构用材的力学强度要求；得到了重组竹12个弹性常数、TL和RL方向的Ⅰ型断裂韧性，并推荐重组竹断裂韧性试样厚度设置为25mm；螺栓抗弯屈服强度随着螺栓直径增大而增大。2.对于销槽承压强度而言，试样尺寸在满足最小要求的前提下，对其无显著影响；螺栓直径、纹理方向和含水率对其影响显著：随螺栓直径增大而减小；随纹角度增大，呈先减小后增大的变化趋势；随含水率增大呈递减趋势，并逐渐趋于稳定。3.销槽试样的纹理角度从0°到90°逐渐过渡时，破坏模式由顺纹理劈裂和销槽端部压溃的混合破坏模式，逐渐向销槽压溃和试样整体压溃的混合破坏模式（试样沿着厚度方向发生分层开裂）转变，以45°销槽试样为转折点。4.采用Eurocode5和NDS/LRFD中的木材销槽公式计算重组竹销槽承压强度，结果偏差较大，故本研究将螺栓直径、含水率、纹理方向作为考虑因素，分别构建了适合于重组竹销槽承压强度的理论计算公式，并给出了重组竹销槽承压测试试样的标准尺寸。5.总结了端距、主构件厚度及螺栓直径等因素对单螺栓承载性能（初始刚度、屈服后刚度、屈服载荷、极限载荷及延性率）影响的显著性，并推荐重组竹螺栓连接节点的主构件厚度设置为90mm，最后结合单螺栓影响因素和销槽承压强度，推导了重组竹单螺栓连接节点承载力理论计算公式。6. Foschi模型能较好模拟单螺栓连接节点承载曲线变化，能反映出弹性区域和屈服后节点特性，并将弹性向塑性的转变过程直观地表现。单螺栓连接节点的有效破坏模式主要有两种，即“一铰”和“二铰”屈服模式，此时主构件和螺栓均能充分发挥材料的力学性能，是合理的破坏模式。7.得出了螺栓列数、行距、间距及每列螺栓数等因素对多螺栓连接节点的承载性能影响变化趋势。随着螺栓间距的增大，试样的破坏形态由列开裂和单铰屈服破坏的混合模式逐渐向单纯的铰破坏演变。多列螺栓随着螺栓列数的增多，会由单列开裂向两边列劈裂演变；随着列间距增大，试样的开裂破坏逐渐消失，只产生了销槽承压破坏和铰屈服破坏。由于多螺栓连接节点在承载过程中载荷分布不均，导致各螺栓的变形不均匀，中间螺栓的变形小于端部螺栓的变形。8.总结了螺栓间距、行距、螺栓个数等因素对多螺栓连接节点承载性能的影响。随螺栓数量的增多，试样载荷-位移曲线的屈服阶段愈加短暂，有些试样几乎从线弹性阶段直接进入破坏阶段，最后结合单螺栓的承载性能，对多螺栓连接节点的有效螺栓数和折减系数进行了计算，并推导了重组竹多螺栓连接节点承载力理论计算公式。更多还原

【Abstract】 Connection is the key design in wood and bamboo structure. The whole structure damagesare always originated by the connection failure. With the development of modern bamboostructure, bolt joint with the traits of simple, safe and reliable, easy to use and so on，has beenused widely. Recently, there was little report on the bolt joint of recombinant bamboo, so it isimportant to study it, for it has an important role in improving the safety and reliability of boltjoint, and providing theoretical basis for its further promotion.Recombinant bamboo that produced by Moso bamboo (Phyllostachys pubescens) wastaken as test material. This research focused on the performance of bolt joint for recombinantbamboo, such as analyzing the effect of several factors on dowel-bearing and bolt jointperformances, observing failure mode and exploring failure mechanism. Besides, theapplicability of the wood-bolted design formula was evaluated for recombinant bamboo. Inaddition, based on the characteristics of recombinant bamboo, theoretical calculation formulasof dowel-bearing strength and bearing capacity were derived, which are benfit for theapplication of bolt joint in modern bamboo structure, providing reliable theoretical basis forperformance improvement of bamboo structural bolt joint, new-typed structural connectiondevelopment.The main results of this research are summarized as follows：1. Recombinant bamboo has uniform density, high mechanical strength and stability,which satisfies the mechanical strength requirements of structural material. Twelve elasticconstants, fracture toughness of modeⅠin TL and RL direction of recombinant bamboo wereobtained. The thickness of the fracture toughness sample for recombinant bamboo wasrecommended to set as25mm. The bending yield strength of bolt increased with the boltdiameter. 2. As to the dowel-bearing strength, there was no significant dimension effect if sampledimension satisfy the minimum requirements. Besides that, bolt diameter, grain angle andmoisture content have significant effect on the dowel-bearing strength.It decreased with theincrease of bolt diameter. It decreased first and then increased with the grain angle increase. Itshowed a decreasing trend with the moisture content increases, and became constant gradually.3. When the grain angle changed from0°to90°, failure mode is from a mixturedamage of the spitting parallel to the grain and crushing on the ends of dowel-bearing sample,to a mixture damage of groove crushing and whole sample crushing (layered crack along thethickness direction of the sample), the45°dowel-bearing sample was as a turning point.4. The dowel-bearing strength prediction values from the wood dowel-bearing strengthformula in Eurocode5and NDS/LRFD were much smaller than the test values. Therefore,theoretical design equations of dowel-bearing strength for recombinant bamboo wereconstructed by introduced bolt diameter, moisture content and grain angle as considerationfactors. Besides, the standard dimension of dowel-bearing strength test samples was arised.5. The effect of end distance, main member thickness and bolt diameter on bearingperformance of single-bolted connection (initial stiffness, post-yield stiffness, yield load,ultimate load and ductility rate) were obtained. A minimun main member thickness ofrecombinant bamboo joints was recommended to set to90mm. the theory formula ofsingle-bolted joint was derived based on dowel-bearing strength, factor effect of recombinantbamboo.6. The load-deformation curves of single-bolted connection simulated by Foschi modelare so well, it could reflect the elastic and yield region characteristics and the transition ofelastic to plastic, visually. Beside, there are two effective failure modes for single-boltedconnections,“one-hinge” and “two-hinge” yield mode. Both of the two failure modes arereasonable, in which the main member and bolt can exert their mechanical properties fully.7. The change trend of bolt rows, row space, the space between adjacent bolts and boltnumbers in each row on the bearing performance of multi-bolted joints were summarized. With the increase of space between adjacent bolts, the failure mode changed from the mixture of rowsplit and “one-hinge” yield to simple hinge yield, gradually. In multi-bolted joints, with the boltrows increase, the failure changes from single split to the both sides split. The split graduallydisappeared with the increasing row spacing, only the dowel-bearing and hinge yield failureemerged. For the non-uniform load distributions, the middle bolts had less deformation thanthe others.8. The effect of end bolt space, bolt and row number on bearing performance ofMulti-bolted connection were obtained.With the increase of bolt number, the yield phase of theload-displacement curve is even more short-lived. Several load-deformation curves almostdirectly changed from the linear elastic stage to destruction stage. Beside, the effective boltnumbers and reduction coefficients those based on the single-bolted connection are calculated,and the theory formula for Multi-bolted joint aslo been derived.更多还原