接管与高颈法兰对接接头无损检测探讨

在实际生产过程中,由于工程技术人员对标准的掌握和理解不够全面,致使我们在应用标准时产生很多不同的观点,有时还会造成不必要的浪费。针对此现象,本文就压力容器中接管与高颈法兰对接接头无损检测问题进行了分析与探讨。     

A shear deformable theory for the analysis of steel beams reinforced with GFRP plates

A shear deformable thin-walled beam theory is developed for the analysis of steel beams reinforced with a GFRP plate to one of the flanges. Starting with the principle of stationary potential energy, the governing equilibrium equations and boundary conditions are formulated for the problem. The theory results in two sets of fully coupled systems of equilibrium equations. The first system describes the longitudinal-flexural response of the system and involves four generalized displacement fields and the second system governs the lateral-torsional response and involves six generalized displacement fields. The resulting coupled systems are then solved numerically for practical problems. Detailed comparisons with three dimensional and shell solutions under ABAQUS show that the present theory provides reliable predictions for displacements and stresses. A comparison with results from a non-shear deformable theory illustrates the necessity of incorporating shear deformation effects in cases involving predominantly twisting responses.     

高强钢内爬插接单管通信塔介绍

本文介绍了一种高强钢内爬插接单管通信塔,结合了插接外爬身体法兰式单管塔的优点,具有外形美观、用钢量经济、安装及维护简单方便、适应节能减排大趋势等特点。     

螺栓法兰连接结构的失效分析及优化设计

针对某种管路螺栓法兰连接结构在实际装配过程中出现的螺栓断裂故障,通过有限元仿真分析及试验,说明了活套环设计刚度不足是导致螺栓断裂的主要原因。为此提出了3种提高活套环刚度的优化设计方案,并对其中增加活套环厚度的方案进行了有限元仿真分析和试验研究,证明增加活套环厚度可有效增加其刚度及螺栓的承载能力,并提高连接结构的可靠性。试验结果表明,改进后连接结构的断裂拧紧力矩比原结构提高了38%,可较好地满足使用要求。     

基于Creo的突缘叉结构轻量化设计

运用Creo软件建立了突缘叉的三维实体和有限元分析模型,计算了额定载荷下突缘叉的应力和变形分布。在此基础上,提出了突缘叉的结构轻量化方案,并对设计变量进行灵敏度分析,确定了影响应力和变形的主要因素。同时运用轻量化优化设计,对突缘叉的结构进一步分析,从而在满足设计要求的基础上使突缘叉的质量相比原方案减轻了22%,且应力大小和变形情况都得到了改善。     

一种高颈铝法兰冲挤新技术

采用了在冲床上两工位无搭边冷冲孔—落料+挤压的复合工艺塑性成形高颈铝法兰管的先进工艺。与传统冷挤压工艺相比省工省料,生产效率高,制件质量好。该工艺在冲挤之前先对条料进行固溶处理,冲挤之后再进行时效处理,从而达到了挤压力量小,制件精度好,外形和性能俱佳的效果。     

Experimental investigation on flexural behavior of concrete-filled pentagonal flange beam under concentrated loading

The flexural behavior of simply supported concrete-filled pentagonal flange beams (CFPFBs) under mid-span loading is experimentally and numerically investigated. There are two CFPFB specimens tested to failure under static load condition to determine the beam flexural capacity. One of the test specimens is designed with a pair of transverse stiffener at mid-span while the other is without any stiffener to resist the load. Both the test specimens have identical geometrical and material properties. From the experimental results, the flexural capacity of the specimen with stiffener is found to be 10% higher than that of the specimen without stiffener. The failure behavior shows the importance of transverse stiffener to enhance the ultimate flexural capacity and to avoid the localized web distortion of the beam. In the numerical study based on finite element (FE) analysis, the concrete and steel materials are modeled using the eight-node solid and four-node shell element respectively. A comparison of the ultimate capacity of the CFPFBs with and without stiffener reveals that the FE models simulate very well the flexural behavior of the test specimens and the difference of maximum load is found to be less than 10%.     

Post-yield response of cold-cambered wide flange steel beams

The post-yield response of steel beams is important in steel fabrication particularly for setting cambers. A commonly used cambering process known as “cold cambering” consists of bending the girder about its strong axis using single or dual symmetrically applied concentrated loads. This paper recasts available solutions for wide flange steel beams relating loads to permanent deformation in parametric form to determine the effect of cross-sectional geometry and load position on its post-yield response. Sensitivity analyses were then conducted to identify appropriate values of these key parameters and their impact on alternative cambering set-ups. This allows optimization of the cold cambering operation for single- and dual-load systems. The analysis shows that dual-load systems offer significant benefits over single-load systems as they develop the required camber profile at smaller loads without overstraining the steel section. The best results are obtained if the spacing between the two loads is kept within one-third to one-quarter of the span.     

梁端翼缘扩翼型节点抗震性能分析

针对梁端翼缘扩翼型节点抗震性能,在试验研究基础上通过建立有限元分析模型衍生设计了2组16个试件,采用Ansys有限元分析方法深入探讨了梁端翼缘扩翼型节点的扩大宽度、扩大长度等参数对节点极限荷载、延性性能等抗震性能影响。根据试验及有限元模拟的试件破坏结果,对容易导致节点断裂发生的薄弱环节的开裂可能性进行了评估,通过引入等效塑性应变指数,从理论上分析了梁端翼缘扩翼型节点的断裂机理。介绍了梁端翼缘扩翼型节点扩翼参数的设计方法。     

Flexural strength of hollow tubular flange plate girders with slender stiffened webs under mid-span concentrated loads

A three-dimensional elastic finite element (FE) model, considering merely the geometric nonlinearity, is used in the first part of this paper to study the overall buckling resistance of hollow tubular flange plate girders (HTFPGs). Modeling is conducted using the general-purpose FE software package ABAQUS under mid-span concentrated loads. The developed model consists of the type and number of elements that allows capturing the different possible buckling mode patterns including local, interactive and lateral-torsional buckling. Finite element results revealed that, unlike the case of conventional beams with solid webs, the moment-gradient factor $C_b$ is significantly influenced by the girder geometry and slenderness. Hence, an equation representing the $C_b$ factor for the case of HTFPGs with slender stiffened webs is proposed. The paper extends to investigate the nonlinear flexural strengths of such girders. The results are compared to the AISC predictions. The original AISC predictions are found to be highly conservative using the code recommended $C_b$ value as well as the current proposed value. However, the suggested AISC strength (found in Hassanein et al., 2013 [1]) using $C_b=1.35$ is found to be the best among other values but it suffers from the discontinuity in the flexural strength-unbraced length relationship. Accordingly, a line representing the middle part of this relationship is currently assumed. Comparisons with FE results indicate that the currently proposed AISC method can fairly predict the flexural strength of the HTFPGs with slender stiffened webs.