Thermal Expansion of Solid Solutions in the ZrTiO4—In2O3—M2O5 (M = Sb, Ta) System

Axial and dilatometric thermal expansions and phase transformations were studied for solid solutions having the α-PbO₂ structure in the ZrTiO₄—In₂O₃—M₂O₅ (M = Sb, Ta) system with nominal formulas of Zr _x Ti _y In _z Sb _z O₄ and Zr _x Ti _y In _z Ta _z O₄ where x + y + 2 z = 2. With increased substitution of z , the cell volume increased, the difference in the b parameters at room temperature between those quenched from 1400° and 1000°C decreased, and the thermal expansion decreased. The axial thermal expansion of ZrTi _y In _z · Ta _z O₄ with z = 0.3 was almost identical with that of HfTiO₄, and those with z = 0.4 and z = 0.45 were smaller than that of HfTiO₄. Unit-cell volumes of these compound were compared with those of single oxides to make it clear that the unit-cell volume of ZrTiO₄ was small anomalously and to distinguish the normal and abnormal substitution systems. These results were explained by the working hypothesis proposed for these compounds.     

带约束拉杆矩形钢管混凝土短柱抗震性能试验研究

为研究带拉杆约束矩形截面钢管混凝土短柱的抗震性能,以轴压比、约束拉杆间距和截面长宽比为主要参数,进行了4个无拉杆约束和11个带拉杆约束矩形钢管混凝土短柱试件的低周往复加载试验。研究了其破坏过程、滞回性能、承载能力、变形能力、刚度退化及耗能能力等,并基于数值分析给出了带约束拉杆矩形截面钢管混凝土短柱压弯承载力计算式。结果表明：钢管板件宽厚比为50和67、剪跨比为3的矩形截面钢管混凝土短柱的滞回曲线饱满,没有明显的捏缩;设置约束拉杆提高了试件的承载能力、变形能力及耗能能力;带约束拉杆试件的极限位移角在1/19~1/50之间,位移延性系数在3.28~6.25之间;破坏时的等效黏滞阻尼系数在0.3以上;增加轴压比降低了试件的延性;减小约束拉杆间距可明显改善柱的抗震性能;保持截面宽度不变,增加截面长宽比,可提高试件承载力,但延性降低。提出的带约束拉杆矩形截面钢管混凝土短柱的压弯承载简化计算式的计算结果与试验结果吻合较好。     

用强度计算结果确定控制混凝土裂缝宽度配筋率

根据《砼结构设计规范》GBJ10 - 89,提出矩形截面受弯构件采用以截面强度计算的配筋率及所配的钢筋直径来确定控制砼裂缝宽度的配筋率的方法。     

钢筋混凝土结构植筋锚固性能探讨与分析

在国内外文献资料的基础上,从黏结锚固性能,承载力、破坏形态拉拔试验和抗震性能等几个研究方面,总结了植筋锚固性能的研究现状,针对植筋锚固性能的试验研究和理论分析,提出了有待进一步深入研究的课题.     

2种轧制温度下BT25钛合金棒材组织与性能

研究了980oc和950℃2种温度轧制的BT25钛合金棒材的室、高温拉伸性能、热稳定性能以及持久性能。研究结果表明,所研究的2种温度下得到的轧制棒材的性能均满足用户提出的标准要求。它们的高温拉伸性能、冲击韧性相当,980℃轧制棒材的室温拉伸性能优于950℃轧制棒材,但后者的热稳定性优于前者,550℃热暴露100h后,后者犟性降低程度较小。BT25钛合金棒材组织比较均匀,均为初生“相和条状届转变组织构成的双态组织,且变形温度较低时,组织较细小,合金的综合性能较高,尤其是热稳定性能较好。     

T形短肢剪力墙的变形杆系广义墙元模型

研究短肢剪力墙的力学模型和计算方法,根据T形短肢剪力墙的受力和变形特点,提出一种10自由度的变形杆系广义墙元模型。考虑翼缘墙与腹板墙的空间耦合作用,运用虚功原理建立T形短肢剪力墙的单元刚度矩阵。为短肢剪力墙结构空间弹塑性分析提供了新的思路,这一宏模型摒弃了现有宏模型中平面假定的限制,不仅可以反映中和轴的移动,而且还可以反映初始截面的剪切翘曲,并且编制了弹塑性时程分析程序,并输入三种不同的地震动进行了算例分析。     

螺旋肋钢丝(PC棒)预应力传递长度的试验研究

螺旋肋钢丝(简称PC棒)是我国新研制开发的用于顸应力混凝土结构的新型钢丝.通过对28个先张法构件端部区域混凝土应变的量测,分析了PC棒预应力传递长度范围内混凝土应变和应力的变化规律以及主要影响因素,提出了PC棒预应力传递长度计算公式的建议,为PC棒的工程应用提供了依据.     

GBT formulation to analyse the behaviour of thin-walled members with variable cross-section

The generalised beam theory (GBT) provides a general solution for the linear/non-linear analysis of prismatic thin-walled structures, using bar elements capable of describing the cross-section rigid-body motions and distortions. Nowadays GBT is fully developed for thin-walled members having a large variety of constant cross-sections. This paper provides the extension of GBT for the special case of thin-walled members with variable open cross-section and the limits of its applicability.     

冷轧带肋钢筋生产工艺研究

依据冷轧带肋钢筋生产中轧制变形量与钢筋性能关系的试验研究成果，确立了不同强度级冷轧带肋钢筋的生产工艺。     

Influence of Carbon Content and Solidification Condition on Incipient Melting of DS Superalloy MAR-M200+2Hf

Hf lowers the incipient melting temperatureof superalloy. As carbon content in Hf-bearingalloy decreases, the incipient melting temperaturedrops furthey. PD ingots have stronger tendencyto incipient melting than HRS ones. Even thoughin PD ingot, the sensitivities at both endsof the ingot are quite different. The meltingof Ni_5Hf phase may be considered as one of themain factors affecting incipient melting. Themore Ni_5Hf the alloy contains, the more seriousthe incipient melting becomes. The results ofdifferential thermal analysis (DTA) have provedthat the peak of 1135-1160℃ corresponds tothe melting range or Ni_5Hf. By means of apretreatment at 1150℃, 8h, Ni_5Hf phase can beeliminated in two ways: the reactionNi_5Hf+γ(C)→MC_(2)+γ and solid solution, andtherefore the final solid solution treatmentcan be carried out at 1260℃. This brings abouta high homogenized structure and further increasesthe stress rupture properties of the alloy at1040℃, 140 MPa.