方支管-H型钢主管T型节点轴压性能数值分析

为研究方支管-H型钢主管平面T型节点的轴压性能,利用有限元软件ABAQUS,对方支管-H型钢主管平面T型节点进行模拟计算,以得到破坏模式和极限承载力.试验结果表明,破坏模式为支管根部屈曲破坏,极限承载力为242 kN,模拟结果和试验结果误差10.5%,有限元能够较好地模拟实验节点,工程中应适当增加支管壁厚以避免支管过快发生屈曲破坏.     

T型方钢管相贯节点轴压性能有限元研究与试验验证

利用通用有限元软件ABAQUS对T型方钢管相贯节点进行了建模及非线性有限元计算.将试件的破坏模式、变形过程、极限承载力与试验进行了校核.研究结果表明:试件在轴向压力作用下,发生弦杆相贯面凹陷和侧壁鼓凸的现象;试件在加载全过程具有较强的变形能力;β值越小,试件的应力强化越时显,延性也越小;试件极限承载力随着β值的增大而增大;有限元模拟与试验吻合度较高.     

圆钢管搭接节点极限承载力计算公式的改进

根据圆钢管搭接节点的最新试验数据和国际管结构数据库数据,对目前平面K圆钢管搭接节点极限承载力计算公式进行了对比分析.结果表明,目前计算公式均不能较好拟合试验数据.为此,提出了在平面K型节点极限承载力计算公式中增加参数.Υ(腹杆与弦杆壁厚比值)和Ov%(搭接率),作为修改现行规范的参考.     

X型方钢管节点平面内受弯性能研究

为考察X型方钢管节点在平面内弯矩作用下的静力性能,通过ABAQUS进行建模及非线性有限元计算,结合验证性试验,对节点的破坏模式、应变强度发展过程、极限承载力进行研究,并讨论轴力和平面内弯矩联合作用对节点极限承载力的影响．结果表明：节点在平面内弯矩作用下,发生弦杆受拉侧鼓凸,受压侧凹陷,腹杆受拉侧焊缝被拉开;节点弦杆最先进入塑性,最终由于塑性变形过大而导致试件破坏;试件极限承载力随着届值的增大而增大;在轴力和平面内弯矩联合作用下,节点的受弯极限承载下降．     

不同受力状态下N型圆钢管完全搭接节点力学性能研究

对正反对称Pratt桁架中出现的直腹杆受压及直腹杆受拉N型圆钢管完全搭接节点的静力性能进行了单调加载的试验研究.实施了1个直腹杆受压和1个直腹杆受拉N型圆钢管完全搭接节点试验.试验研究结果表明:直腹杆受压的破坏模式为直腹杆平面外倾斜及斜腹杆管壁表面塑性,直腹杆受拉的破坏模式为弦杆管壁与斜腹杆管壁表面塑性及母材开裂;欧3规范较中国规范精度更高,且直腹杆受压时中国规范偏于不安全;直腹杆受拉情况下节点承载力性能优于直腹杆受压情况下,极限承载力提高近42%.     

钢筋再生混凝土梁的抗剪性能

结合国内外大量相关试验成果,本文对钢筋再生混凝土梁的抗剪性能进行了较为系统的研究分析,主要包括钢筋再生混凝土梁的抗剪受力及破坏特征,影响钢筋再生混凝梁抗剪承载力的主要因素以及钢筋再生混凝梁抗剪承载力的计算方法等。研究结果表明,钢筋再生混凝土梁的破坏形态与普通混凝土梁差别不大,主要取决于剪跨比;再生混凝土强度、剪跨比和配箍率以及再生骨料取代率是影响钢筋再生混凝土梁抗剪性能的主要因素;钢筋再生混凝土梁的抗剪机理与普通混凝土基本相同;普通混凝土梁抗剪承载力计算公式应用于再生混凝土偏于不安全。本文的研究成果对再生混凝土在结构中的推广应用具有一定的实际意义和价值。     

X型插板焊接方管节点轴压承载力的有限元分析

以X型插板焊接方管受压节点的试验数据为基础,运用ABAQUS软件对节点进行了模拟分析,校验了节点轴压极限承力、应变分布和破坏模式等方面的非线性有限元建模方法.研究结果表明:在承受轴压作用时,节点焊缝附近的插板局部屈曲,平面外失稳而倾斜;插板板厚相对于方管的较小,工程中应采取增加插板厚度或在插板两边设置加劲肋等加强措施;节点的塑性变形能力较差,使得破坏呈脆性.     

焊缝模型对圆钢管节点极限承载力影响有限元分析

以圆钢管节点试件的试验数据为基础,通过非线性有限元计算可知两腹杆的极限承载力具有焊缝有限元计算值略微大于无焊缝有限元计算值,且具有焊缝模型有限元极限变形计算值小于相应无焊缝模型有限元极限变形有限元计算值.以节点处增加一圈壳体单元,并取此壳体单元厚度为弦杆壁厚的一半的方法,建立壳体焊缝有限元模型.实体和壳体有限元参数分析结果均表明:焊缝模型的建立均使得圆钢管节点刚度增加,导致节点极限承载力提高.具有焊缝的壳体有限元模型计算结果与试验相比仍然有较大误差,而实体有限元与试验结果比较接近.     

基于ANSYS的实木家具节点有限元分析研究

本文系统地论述了应用ANSYS有限元分析软件进行实木家具节点有限元分析的方法,并以采用直角榫接合的T型构件为例进行了验证,同时与材料力学的位移计算公式及传统的模拟方法进行对比分析,通过横向构件的端部位移及节点应力分布来考察其模拟效果。结果表明本文所介绍的节点半刚性模拟方法要比结构力学的计算公式以及传统的节点刚性模拟方法所得到的结果更加合理。     

新型装配式槽钢连接节点有限元分析

针对焊接节点易出现脆性破坏的问题,提出一种钢管混凝土柱-H型钢梁槽钢连接节点。对6个试件进行Abaqus有限元分析,模拟分析节点在低周反复荷载下的抗震性能。结果表明,轴压比增大会增强节点的耗能能力,轴压比为0.4时节点的耗能能力最好;翼缘连接板厚度增加会增加节点的承载力和耗能能力,最优的翼缘连接板厚度为10 mm。     

Plug shear failure in nailed timber connections

Brittle failures in mechanical timber joints should be avoided, because this often results in low capacity and brittle failure of the structure. Nailed joints experience three ultimate failure modes: embedding, splitting or plug stear failure. To avoid plug shear failure, short and wide joints are preferred, limiting the number of fasteners in line with the load and grain direction. Plug shear failure was examined in short-term experiments on nailed steel-to-timber joints in glulam loaded in tension parallel to the grain with five different joint geometries. The aim of the study was to examine if the fastener group layout can be adjusted to avoid plug shear failure and to gain an insight into the causes of failure initiation. Using spring models, it is shown that the load distribution creates pronounced stresses at the last nail in the joint, which probably initiates the plug shear failure. Test results are compared with prediction models found in the literature. It was found that fasteners placed in groups can be a successful way of reducing the risk of plug shear failure. The failure is probably initiated at the nail farthest from the free end, where tensile stresses perpendicular to grain occur.     

Stabwerkträger mit geleimten Knotenpunkten

The strength behaviour of 27 glued node joints for plane frameworks was determined in short-time failure tests. The different types of nodes and varying types of joints per node were tested. The longitudinal changes of the members at the nodes were measured, using glue-fixed strain gauge strips and novel strain gauge extensometers. After evaluating the test results from single nodes, not only shorttime failure tests, but also tests under dynamic long-duration load (about 10⁶ cycles) with concluding failure tests were carried out on twelve glued frameworks. The results confirm the reliable bearing behaviour of these types of structure. A reduction in bearing capacity due to dynamic long-duration load could not be detected.     

Stabwerkträger mit geleimten Knotenpunkten

The strength behaviour of 27 glued node joints for plane frameworks was determined in short-time failure tests. The different types of nodes and varying types of joints per node were tested. The longitudinal changes of the members at the nodes were measured, using glue-fixed strain gauge strips and novel strain gauge extensometers. After evaluating the test results from single nodes, not only shorttime failure tests, but also tests under dynamic long-duration load (about 10⁶ cycles) with concluding failure tests were carried out on twelve glued frameworks. The results confirm the reliable bearing behaviour of these types of structure. A reduction in bearing capacity due to dynamic long-duration load could not be detected.     

木桁架齿板连接节点抗剪性能的研究

轻型木桁架节点由齿板钉接,除了接合节点受拉伸以外,根节点和腹杆节点受到剪切与拉伸组合或剪切与压缩组合作用,因此对齿板连接节点抗剪能力的确定十分重要。本文参照我国现行木结构设计规范中有关"齿板连接节点试验"的要求,对M-20齿板极限受剪承载力进行了试验,确定了承载力设计值,并讨论了齿板主轴与荷载之间夹角的变化对齿板连接节点抗剪承载性能的影响。     

钢绳定尺软包装工艺参数的确定

通过求解钢绳在工字轮中最紧密排列时的有效体积系数，推导出了工字轮容绳长度理论公式；采用符合钢绳包装实际情况的加粗绳径修正理论公式的方法确定了实用公式，建立了包装宽度与外径之比符合黄金分割率的补充方程，用试凑法初步设计出软包装参数，提出了保证软包装重心不偏移的条件及修正设计参数的方法。     

Experimental investigation of end-notched glulam beams reinforced with GFRP bars

End-notched timber beams can have a significant decrease in load-carrying capacity as a consequence of stress concentration due to height reduction at the supports. To prevent crack opening and its propagation at the notches, these beams are usually reinforced. In this paper, extensive experimental research on end-notched glulam beams reinforcement with glass fibre reinforced polymer - GFRP bars is presented. Bending tests on unreinforced and reinforced end-notched glulam beams were carried out until the point of failure. Behaviour of tested beams is described through load–deflection diagrams, failure modes and ultimate loads. In addition, different reinforcement schemes of notches were analysed in order to determine an optimal configuration under the aspect of load-carrying capacity improvement in relation to the unreinforced beams. The effectiveness of GFRP bars as a reinforcement of end-notched glulam beams was evident from significantly increased ultimate load and deformability. The design procedures for unreinforced end-notched beams according to Eurocode 5 and reinforced end-notched beams according to German national annex of Eurocode 5 were analysed through comparison with the experimental results. Recommendations for the design of GFRP reinforcement are given.