Cyclic response characteristics of retrofitted moment resisting connections

Experimental studies were conducted in order to investigate the behavior of the weld in steel moment resisting connections. A total of forty seven reduced-scale subassembly model specimens were tested that represent welded moment resisting connections of the beam to box column. These specimens were used to study the following aspects in fabrication and retrofitting of moment resisting connections: Complete joint penetration (CJP) groove weld behavior, transversely loaded fillet weld behavior, grinding and rewelding influence on weld behavior, reinforcing of connection with T-stiffener and rib plates, strain rate effect on weld and material characteristics and electrode toughness effect on weld behavior. Following test result interpretations, five full-scale moment resisting connections of beam to box column were fabricated and tested. These models included one specimen fabricated with details of an outdated connection, two specimens with an improved CJP groove weld detail, and two specimens retrofitted by T-stiffeners. Each specimen was subjected to a standard quasi-static cyclic load pattern. Overall, the improved and retrofitted specimens performed well, achieving total (elastic plus plastic) story drift ratios of at least 4% radians in magnitude before experiencing 20% strength degradation.     

管壳式换热器部件的应力分析及强度校核

本文对某换热器的前管板在机械载荷和热载荷下利用有限元分析软件ANSYS进行强度分析。在分析时,首先进行热分析得出温度分布,得出温度最大值出现在换热管与管板接触区,且最大值为150.408℃。然后在热分析的基础上进行应力分析,得出最大应力出现在螺栓连接处,且为174 MPa。最后参照JB4732-1995《钢制压力容器分析设计标准》采用线分析法选取7处危险区域进行应力评定,得出3处应力(为机械载荷和热载荷的总应力)最大为174 MPa小于安全值438 MPa。所以该换热器在运行过程中是安全的。     

垫片螺栓法兰连接系统的载荷与变形分析

分别在预紧和操作情况下 ,应用弹性理论对螺栓法兰系统进行了较为详细的载荷 变形分析 ,同时提出了将方程组的求解转化为优化问题 ,应用遗传算法结合牛顿迭代法来求解相关的非线性方程组。算例表明 ,考虑法兰旋转时更能反映螺栓法兰系统的真实受力情况。     

Cyclic loading behavior of EBF links constructed of ASTM A992 steel

Cyclic loading tests were conducted to study the behavior of link beams in steel eccentrically braced frames. A total of thirty-seven link specimens were constructed from five different wide-flange sections, all of ASTM A992 steel, with link length varying from short shear yielding links to long flexure yielding links. The occurrence of web fracture in shear yielding link specimens led to further study on the cause of these fractures. Since the link web fracture appeared to be a phenomenon unique to modern rolled shapes, the potential role of material properties on these fractures is discussed. Based on the test data, a change in the flange slenderness limit is proposed. The link overstrength factor of 1.5, as assumed in the current U.S. code provisions, appears to be reasonable. The cyclic loading history used for testing was found to significantly affect link performance. Test observations also suggest new techniques for link stiffener design and detailing for link-to-column connections.     

波导管与法兰盘电铸连接工艺的研究与应用

在波导管两端面上连接法兰盘时通常采取的是银钎焊工艺,由于银钎焊是一种高温连接从而带来了很多弊病：本文在充分论证试验后,实现了将波导管与法兰盘直接电铸成一体的新工艺技术。同时,本文还阐述了在实施该工艺过程中是如何较好地解决电铸模芯材料、连接强度、致密与韧性三大关键性技术。     

浅析熔体管道材料设计

通过总结大型化工项目中的工程经验,详细介绍了熔体管道系统中管道、法兰、垫片和阀门的设计及选用,为熔体管道材料工程设计提供了可靠的设计参考。     

非对称型材弯曲拉伸失稳及最小弯曲半径研究

以槽型材为例,借助塑性力学分析手段,对非对称型材弯曲过程中拉伸失稳问题进行研究。分析非对称型材弯曲时出现分散性失稳和集中性失稳时的应变强度。为避免出现拉伸失稳现象,提出非对称型材最小弯曲半径的计算方法。最后通过实际算例,将解析解与数值模拟结果进行比较分析。结果表明,型材在弯曲状态下,发生分散性失稳的应变强度小于集中性失稳,它与应力分布状态和材料硬化指数有关。最小弯曲半径与材料力学性能和截面尺寸有关。     

长腹板的极限抗剪强度

20世纪60年代初期和70年代开发的Basler模型和Rockey模型,都可以很好地预测在板的加劲肋间距与腹板深度比值小于或等于1.5,并承受纯剪力作用时腹板的后屈曲强度。当这个比值大于或等于3.0时,模型计算便失去了其准确性。现在大部分钢结构都是建立在这两个主要理论或是考虑到后屈曲阶段张力场作用的储备强度后的衍生理论的基础之上。然而,没有一个理论能解释腹板上复杂的应力分布,直到Yoo和Lee提出剪力作用下腹板后屈曲性能的真实受力机制。     

塔设备法兰强度计算的几个问题

分析了不同载荷对塔设备法兰受力的影响,指出计算承受外载的法兰强度应根据不同的载荷选取不同的方法。     

Local buckling and slenderness limits for flange outstands at elevated temperatures

This paper presents a study of the inelastic local buckling of flange outstands in thin-walled steel beams at elevated temperatures. A spline finite strip method of buckling analysis is modified in order to model the properties of the steel section at elevated temperatures, so that slenderness limits can be proposed. These limits are needed in describing the behaviour of members under fire loading, since the development of benign catenary action in a restrained beam that has received widespread research attention in fire engineering design is reliant on the formation of plastic hinges, and of the influence of local buckling on the formation of these hinges. A sensitivity analysis is undertaken in order to propose plasticity and yield slenderness limits at elevated temperature, and it is shown that these limits depend on the parameters describing the uniaxial stress-strain relationship at the elevated temperature. The local buckling temperature is predicted for two different boundary conditions for a flange outstand, and it is shown that at high temperatures the local buckling of the beam is highly significant in accelerating the favourable development of catenary action.