特征延性系数谱及RC框架的目标位移

通过大量计算分析 ,探讨了地震作用下弹塑性单自由度体系位移延性系数 μΔ 与特征强度比cy,屈服位移Δy 之间的关系 ,建立了单自由度体系的 μΔ cy Δy 曲线 ,即特征延性系数谱。提出了两种确定钢筋混凝土框架的屈服基底剪力和屈服顶点位移方法。探讨了通过多 单自由度体系转移 ,利用特征延性系数谱和结构的弹性参数求解规则均匀框架弹塑性目标位移的方法。还给出了一个 1 2层规则RC框架目标位移计算的算例。     

Hot Workability of as‐Cast High Manganese‐High Carbon Steels

In order to produce new high Mn‐high C austenitic steels (R_m>700 MPa), different tests and methods were used to determine a suitable window of process parameters. In‐situ melting hot tensile tests and hot compression tests were carried out to investigate the hot ductility, fracture characteristics and flow behaviour during continuous casting and hot deformation of 3 steels with Mn and C contents between 9‐23% and 0.6‐0.9%, respectively. The results show that these steels are susceptible to interdendritic fracture at high temperatures. Decreasing Mn content improves the reduction of area at high temperatures to 60% or more. Hot deformation loads for processing the investigated steels are not higher in comparison to the stainless steel 1.4301.     

薄壁钢管混凝土节点的试验研究与ANSYS有限元分析

通过对8个薄壁钢管混凝土柱与组合梁节点的试验研究,得出了各类节点受力性能的一般规律.试验证明,各节点均具有较高的承载力和较好的延性性能.采用ANSYS有限元程序中的Solid 65单元和Shell 181单元分别来模拟组合梁、柱中的混凝土和薄壁钢板对节点进行有限元分析,理论计算结果与试验基本吻合.     

碳纤维布加固混凝土梁抗弯试验研究

粘贴碳纤维布加固混凝土是一种新兴的加固技术.本文通过对比粘贴不同层数碳纤维布混凝土梁试验,证明随着碳纤维布粘贴层数的增加,加固梁承载力、刚度、对裂缝开展的抑制作用及梁的最终挠度增加.碳纤维布起到了很好的加固效果.     

Creep Properties of Base Metal and Welded Joint of Hastelloy XR Produced for High-Temperature Engineering Test Reactor in Simulated Primary-Coolant Helium

Creep tests of base metal, weld metal and welded joint of Hastelloy XR, which had the same chemical composition as Hastelloy XR produced for an intermediate heat exchanger of the High-Temperature Engineering Test Reactor, were conducted in simulated primary coolant helium. The weld metal and welded joint showed almost equal to or longer rupture time than the base metal of Hastelloy XR at 850 and 900°C, although they gave shorter rupture time at 950° C under low stress and at 1,000°C. The welded joint of Hastelloy XR ruptured at the base metal region at 850 and 900°C. On the other hand, it ruptured at the weld metal region at 950 and 1,000°C. The steady-state creep rate of weld metal of Hastelloy XR was lower than that of base metal at 850, 900 and 950°C. The creep rupture strengths of base metal, weld metal and welded joint of Hastelloy XR obtained in this study were confirmed to be much higher than the design allowable creep-rupture stress (S_R ) of the Design Allowable Limits below 950°C.     

Cast structure and property variability in gamma titanium aluminides

Aspects of cast structure that influence mechanical property variability, and in particular tensile ductility, have been studied in a Ti-48Al-2Cr-2Nb titanium aluminide alloy. Macrostructure, porosity, microstructure and tensile properties have been characterized over a range of casting processing conditions. Local solidification times and subsequent solid-state cooling rates during casting have been characterized via local thermal measurements in combination with solidification modeling. Large variations in cooling rate during casting dramatically influence the initial cast structure as well as the distribution of defects such as porosity. Variations in as-cast structure persist through subsequent thermal and hot isostatic pressing cycles and contribute to the variability of tensile ductility. The current understanding of the relationship of tensile ductility to processing-induced changes in structure will be briefly discussed.     

Physical Simulation to Determine High TemperatureMechanical Behavior of Continuously Cast Steels

Hot ductility and strength of Continuous casting(CC) steels at elevated temperatures from CC processeswere studied by physical simulation. The method is the hot ductility test. The design of test parameters and datainterpretation are discussed. The results show that the bulging of CC steel slabs which is caused by the mechanismof creep has great influence on the formation of central segregation and internal cracks. Creep tests including staticcreep tests and dynamic creep ones were performed at 1200 and 1300℃. Effects of strain rate and temperature onhot ductility are also discussed and a simple model is presented to explain the interaction between hardening and softening.     

关于钢纤维砼在局部压力作用下的强度和延性的研究

介绍钢纤维砼在局部压力作用下的强度和延性的变化规律，再与砼中配有钢筋网片的情况对比，得出了提高砼局部抗压能力的有效方法。     

Ductility and toughness in intermetallics

Limited ductility and toughness at low temperatures are serious disadvantages in intermetallics. As in other metallic materials, the two major brittle failure modes in intermetallics are cleavage and intergranular fracture. We focus on cleavage fracture and the corresponding brittle-to-ductile transition mechanism. To prevent cracking, a ‘sufficient number’ of dislocations must be generated at a crack tip, and this ‘sufficient number’ appears to be very large. This event is more like a phase transition than an ordinary thermally activated process. In this paper a new theoretical model, proposed to explain the BDT is summarized. The micro-structural implications of this model are presented and the means of achieving an acceptable combination of strength and toughness through microstructural control are then discussed, along with examples.     

钙处理对集装箱板钢铸坯高温延塑性影响研究

测定了集装箱板钢的高温力学性能 ,并比较钙处理和合金元素对其的影响。试验结果表明在1× 10 - 3 / s应变速率下 ,集装箱板钢连铸坯在凝固温度～ 6 0 0℃间存在两个脆性温度区域。细小的脆性夹杂物Ca S优先析出并聚集在奥氏体晶界 ,使晶界进一步脆化 ,造成钙处理钢铸坯试样在 80 0～ 90 0℃时的延塑性低于未经钙处理钢试样。为提高耐大气腐蚀能力而添加的合金元素 P对其高温力学性能没有造成明显不利影响。同时结果表明集装箱板钢试样的零强度温度 (ZST)在 144 0～ 145 0℃左右 ,零延性温度 (ZDT)在 140 0～ 1410℃左右。