钢筋混凝土钻孔咬合桩的施工实践及方法介绍

某工程基坑围护结构采用钢筋混凝土钻孔咬合桩,桩径Ф100cm,桩中心距80cm,桩长21-31m,咬合厚度20cm。本文介绍该钻孔咬合桩的施工方法与质量安全措施,并简述施工中出现的问题及采取的措施。     

腹板开洞连续组合梁洞口补强方法研究

提出几种不同的腹板开洞连续组合梁的洞口补强方式,通过有限元计算对不同补强方法的连续组合梁的力学性能进行了比较.计算结果表明,组合梁洞口区域采取补强措施后能够在一定程度上提高洞口区域的抗弯和抗剪承载力,增强其刚度和局部稳定性,并得到了比较有效的洞口补强方法可以用于工程实践.     

厚壁型复合烧结页岩空心砌块性能研究

结合已有专利,综合应用有限容积法和有限元法研制了一种厚壁型复合烧结页岩空心砌块,该砌块具有良好的热工性能和力学性能,可用于墙体自保温承重体系.研究了填充不同保温材料和不同砌筑方式对砌块热工和力学性能的影响,指出填充材料主要影响热工性能,砌筑方式主要影响力学性能.并通过研究表明,叠砌砌块造成的通长孔对墙体热工性能影响很小,应防止砂浆形成热桥.     

基于振动法的抗疲劳断裂水泥稳定碎石强度标准研究

强度是水泥稳定碎石材料设计与施工质量控制重要指标。当集料类型、矿料级配和成型方式一定情况下,水泥稳定碎石强度取决于水泥剂量。强度标准越高,则水泥剂量越大,水泥稳定碎石抗荷载破坏能力越强,但抗收缩开裂能力越差;反之亦然。为此,以水泥稳定碎石基层施工期和运营期在荷载作用下不发生疲劳破坏所需材料最小强度为准则,研究了水泥稳定碎石力学强度特性、疲劳特性及施工期与运营期水泥稳定碎石基层荷载响应,提出抗疲劳断裂的水泥稳定碎石强度标准。结果表明：为防止施工车辆荷载作用下基层发生极限断裂破坏,水泥稳定石灰岩碎石基层必须养护7d后,且其劈裂强度达到0.68MPa以上,方可进行下结构层施工;为防止设计年限内基层在施工车辆和运营车辆反复作用下产生疲劳断裂,水泥稳定石灰岩碎石7d劈裂强度不小于0.70MPa。为了便于应用,结合抗压强度和劈裂强度之间关系,提出水泥稳定石灰岩碎石7d抗压强度不小于7.0MPa。     

A probabilistic approach for economic analysis of a shopping center in seismic zone

The occurrence of an earthquake causes direct and indirect losses in economy. Performance of the built environment can determine both the magnitude of the losses and the speed of recovery from earthquakes. Earthquake losses can be minimized by the use of planning techniques. This paper presents a probabilistic approach for economic evaluation of a shopping center constructed in a seismic zone. Decision-makers can benefit from this approach, before and after an earthquake occurrence, by considering the probability distribution and variability. Life cycle cost concept is taken into account in the formulation of future worth estimation. Therefore, the approach simulates all the benefits and costs, which are prone to variation within Monte Carlo framework. The probabilistic approach can be used to assess the effects of recovery periods.     

Monte Carlo simulation of extreme traffic loading on short and medium span bridges

The accurate estimation of site-specific lifetime extreme traffic load effects is an important element in the cost-effective assessment of bridges. A common approach is to use statistical distributions derived from weigh-in-motion measurements as the basis for Monte Carlo simulation of traffic loading. However, results are highly sensitive to the assumptions made, not just with regard to vehicle weights but also to axle configurations and gaps between vehicles. This paper presents a comprehensive model for Monte Carlo simulation of bridge loading for free-flowing traffic and shows how the model matches results from measurements on five European highways. The model has been optimised to allow the simulation of many years of traffic and this greatly reduces the variance in calculating estimates for lifetime loading from the model. The approach described here does not remove the uncertainty inherent in estimating lifetime maximum loading from data collected over relatively short time periods.     

绿色施工在工程项目中的应用

结合工程实践介绍绿色施工主要途径、方法和措施,探索建立绿色施工的发展模式,发挥绿色施工的引领和示范作用,实现"四节一环保"。     

Developing eco-friendly methods for purification of compounds derived from hydrogenated cardanol

The present work made a comparative study between two purification methods, column chromatography and recrystallization, for compounds derived from cardanol, a by-product of the cashew industry (Anacardium occidentale L.). The compounds were successfully synthesized and characterized, focusing our attention to results obtained in terms of yield, purity, generation of solid waste and amount of solvent used in each purification process. For all the synthesized compounds, the amount of solvent used was greatly reduced in the recrystallization process, with purities above 80%, when compared to chromatographic column, which still demands high amounts of eluent.     

Solvent and Extraction Conditions Control the Assayable Phenolic Content and Antioxidant Activities of Seeds of Black Beans,Canola and Millet

The effects of extraction solvent and conditions on the total phenolic content (TPC) and antioxidant activity of black beans, canola and foxtail millet were investigated. The antioxidant activity was assayed using 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging activity (DRSA) and oxygen radical absorbance capacity (ORAC). Four solvent systems, namely 70 % acetone, 80 % ethanol, 80 % methanol and a mixture of acetone/methanol/water (7:7:6, v/v/v) were used. The extraction methods adopted in this study included refluxing, homogenization, cold extraction and sonication. The TPC as measured using the Folin Ciocalteu's method were 12.35–28.39, 2.43–16.73, and 1.78–5.06 µmol catechin equivalents/g dry matter (dm) for canola, black beans and foxtail millet, respectively. Aqueous acetone afforded the highest TPC for black beans and canola. Within the same solvent system used, the TPC, DRSA and ORAC obtained from different extraction techniques differed for black beans, canola and foxtail millet. The results demonstrated that the solvent system as well as method influenced the extraction of phenolic compounds and their antioxidant activities, depending on the type of matrix in which phenolics were embedded.