管廊隧道开挖对上覆在建深基坑影响的三维有限元分析

以沈阳某盾构法综合管廊隧道下穿在建盖挖顺做法基坑为工程实例,在对工程实测数据进行分析基础上,利用小应变硬化本构模型进行三维有限元数值模拟研究,分析了盾构隧道下穿在建基坑引发的围护结构位移、水平支撑变形和基坑内既有结构变形。研究表明,利用小应变硬化本构模型可对盾构隧道下穿在建基坑问题进行较好的模拟;盾构隧道下穿基坑将引发围护结构顶部产生差异沉降;基坑内已施工完成的结构和水平支撑将发生"两边沉降大,中间沉降小"的上凸型变形;合理设计的立柱可有效控制盾构下穿引发的水平支撑沉降。     

匙孔效应对激光熔覆层横截面几何形貌的影响研究

目的 研究匙孔效应在不同激光功率、扫描速度和送粉速率工艺参数下,对熔覆层横截面形貌的影响规律,并揭示匙孔对基体的作用机制。方法 利用光束模式为高斯光束分布的YLS-3000光纤激光器进行熔覆镍基高温合金Ni35实验。利用光学显微镜（OM）采集熔覆层横截面宏观形貌,并用金相分析软件以及计算机辅助绘图软件对熔覆横截面参数进行测量。结果 随激光功率的增加,匙孔深度增加;随送粉速率和激光扫描速度的增加,匙孔深度减小。随送粉速率的增加和激光功率的减小,熔覆层横截面左右垂直段高度值（H2和H4）减小;随扫描速度的增加,H2和H4先增加再减小。在激光熔覆过程中,当基体没有形成匙孔时,H2和H4的值为零,熔覆层与基体混合区域的横截面形貌为月牙形;当在基体中形成匙孔时,H2和H4的值大于零,熔覆层与基体混合区域的横截面形貌为蘑菇形。结论 在激光熔覆过程中,不同激光功率、扫描速度和送粉速率工艺参数对匙孔的影响机制不同。匙孔效应的强弱显著影响熔覆层横截面参数H2和H4的大小,进而影响熔覆层形貌。     

Influence of Impurities and Oxidation on Hydroconversion of Waste Cooking Oil into Bio-jet Fuel

The influences of impurities and oxidation evolution of waste cooking oil on the preparation of bio-jet fuel via hydroconversion were studied. The hydrogenation active sites and acid sites were covered by heavy metals, sulfides, and basic nitrogen compounds, resulting in the increase of selectivity for bio-jet fuel by decreasing the selectivity of diesel, aromatics, and iso-alkanes. The effects of impurities, oxidation on the reaction pathway, and product distribution became more distinct with higher catalyst acidity. The evolution and variation of naphthalene, indan, and phenanthrene obtained from cyclic fatty acids influenced the properties of fuel or evoked the catalyst deactivation. This work will help to design new catalysts for selective conversion of waste cooking oil into bio-jet fuel.     

组合梁钢筋混凝土柱框架结构力学性能非线性有限元分析

基于Opensees地震工程数值模拟平台,实现了组合梁钢筋混凝土柱单层单跨平面框架结构在单调水平荷载作用下骨架曲线的有限元模拟,并与相关试验结果进行对比分析.数值模型中,混凝土采用修正的Kent-Park模型,钢材采用理想弹-塑性模型,并采用位移增量法控制加载.基于此,对影响此类框架结构P-Δ曲线的因素进行了参数分析,抗震性能良好.     

A temperature fluctuation equation model dedicated to the computation of turbulent thermal layers in high Reynolds internal flows

The paper deals with the modelling of temperature fluctuations in the fresh gases for the simulation of turbulent internal flows. For this purpose, a transport equation for the sensible enthalpy variance is treated. The proposed dynamic model for the scalar dissipation rate incorporates the effect of the turbulent Reynolds number. The wall closure is based on a non-isothermal formulation and accounts for the non-equilibrium state of the boundary layer. The developed models are implemented into the compressible code IFP-C3D. Results of the computations are successfully compared with experiments and DNS data for a slightly heated jet and moderate non-isothermal walls.     

Full-scale testing of a parking structure column retrofitted with carbon fiber reinforced composites

A proof test was performed to investigate the improved seismic performance of parking structure columns retrofitted with carbon fiber composite jacketing. One full-scale square column with details simulating the typical existing parking structure columns designed following the pre-1971 codes was constructed and tested under constant axial load, cyclic shear and moment in double bending condition. Assessment analysis indicated that the column in ‘as built’ condition would suffer either a brittle shear failure or a premature failure due to lap-splice deterioration. Such failure modes could be avoided by the carbon fiber composite jacketing, which allowed the column to develop excellent hysteretic response with stable load carrying capacity and significantly improved ductility.     

模糊综合法在结构设计中的应用

介绍了模糊综合评判方法在结构设计阶段成本控制中的应用,提出了基于单目标的模糊综合评判逆向计算法,该方法可在分析模糊评判基础上指明结构设计优化的方向。结果表明,模糊综合评判方法可用于评判结构设计方案对建设成本的影响,模糊综合评判逆向计算法拓展了模糊综合评判方法的应用范围,值得进一步研究。     

应用MR阻尼器的连续梁桥地震损伤控制方法

基于地震作用下连续梁桥的损伤破坏机理,利用MR阻尼器控制元件,建立了基于桥墩广义水平刚度比的阻尼器出力方案,提出了连续梁桥的非线性地震损伤控制方法。对某一联三跨连续梁桥进行地震损伤控制研究,采用IDA(Increasing Dynamic Analysis)方法对控制前后桥梁结构进行损伤分析,结果表明所提出的控制方法可以有效降低桥梁损伤,并使桥墩损伤趋于均匀,显著提高桥梁的抗震性能;对采用不同控制方案和不同设计传递系数的桥梁进行地震损伤分析,结果表明半主动控制方案对墩梁残余位移和桥墩损伤的控制效果优于PON(Passive On)控制,并且设计传递系数对控制效果影响较大,需合理选用。     

形状记忆合金在复合材料损伤监测中的应用

复合材料的损伤会对结构的可靠性和安全性造成威胁,近年来引起国内外专家和学者的广泛关注。本文将形状记忆合金(SMA)埋入复合材料试件中,通过对SMA电阻变化与复合材料应变之间的关系进行讨论,建立不同监测条件下复合材料的损伤监测理论模型。基于该模型讨论了不同初始状态下SMA材料的损伤监测行为。研究结果表明:复合材料的损伤与SMA电阻变化呈线性关系,温度荷载在SMA未发生相变时对损伤监测影响较小,在SMA发生相变时对损伤监测影响较大。本研究可为基于SMA的复合材料损伤监测理论的进一步工程应用提供理论指导。      

苏丹Palouge FPF区块含水原油热化学脱水特性研究

通过室内实验对加入不同类型破乳剂的苏丹Palouge FPF含水原油热化学沉降特性进行研究。结果表明,高效破乳剂TS-101最适合现场原油脱水,经过不同乳化条件乳化之后的不同含水率的稳定原油乳状液,加入TS-101破乳剂的最优破乳温度为80℃,最佳质量浓度为170~180mg/L,大部分试验油样在沉降13h后慢慢趋于稳定,沉降19h后全都符合预期脱后含水率低于5%的指标。