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The Finite Element Analysis of the Differential Settlement Prediction for the Adjacent Longitudinal Precast Box Culvert 相邻纵向预制箱涵差分沉降预测的有限元分析
Pub Date : 2019-04-28 DOI: 10.11648/J.AJCE.20190701.16
Zenagebriel Gebremedhn, Jilong Li, Guofu Qiao
This paper presents the finite element analysis of the differential settlement prediction for the adjacent longitudinal precast box culvert and subject to different loading conditions including different loading area. These culverts were investigated based on the finite element method was used to analyze the numerical solution of the problems under the condition of assembled of the standard three dimensional adjacent box culvert with beneath soil, side soil and floor reaction under different loading conditions and loading areas. It is located on right side soil of box culvert concerning to settlement which is using brick element in ABAQUS software. The culvert, floor reaction and soil were modeled using standard parameters of three dimensional solid geometric and material linearity. Finally, the settlement foundation was predicted using the finite element modeling and analysis, the screw bolt constraint is equivalent to the binding contact (tie constraint) so that the screw bolt connection has a negative impact on the performance of the side wall of adjacent longitudinal box culvert specifically if there is a settlement occurred.
本文对相邻纵向预制箱涵在不同荷载条件下(包括不同荷载区域)的差分沉降预测进行了有限元分析。采用有限元法对标准三维相邻箱形涵在不同荷载条件和荷载区域下的下土、侧土和底板反力组合问题进行了数值求解。在ABAQUS软件中采用砖单元对箱涵进行沉降处理,将其定位在箱涵右侧土体上。采用三维实体几何线性和材料线性的标准参数对涵洞、底板反作用力和土体进行了建模。最后,利用有限元建模分析对沉降基础进行预测,螺杆约束等效于约束接触(绑扎约束),使得相邻纵箱涵发生沉降时,螺杆连接对侧壁性能产生负面影响。
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引用次数: 1
Rules Regulating the Change in Physiological Parameters of Rats Under Simulated Microgravity and Different Ambient Temperatures 模拟微重力和不同环境温度下大鼠生理参数变化的调控规律
Pub Date : 2019-04-28 DOI: 10.11648/J.AJCE.20190701.15
Jie Qian, Gengxin Xie, Jie Zheng, Bo Duan, Yajun Cao, Xi Wang, Fengjie Li, Changpeng Hu
To investigate the rules regulating changes in mean chest temperature (MCT), mean rectal temperature (MRT) and mean body weight (MW)in rats at simulated microgravity and different ambient temperatures (ATs). The −30o rat tail suspension (TS) method was used to simulate microgravity over a 7 day period at 18°C, 20°C, 23°C and 26°C AT through comparison between the TS group and control group. Each group contained six male SD rats (including one verification rat). MCT and MRT of TS group rats increased at all four levels of AT. MCT and MRT reached maximum growth rates of 0.315 and 0.118 at ATs of 20°C and 23°C, respectively. MW was reduced at ATs of 20°C and 23°C, whereas it increased at 18°C and 26°C AT in the TS group. The rates of changes of MCT, MRT and MW at different ATs were analyzed using linear regression analysis for both the control (Equation 1) and TS (Equation 2) groups. Using A new equation (Equation 3) without the influence of other factors was derived after Equation 1 minus Equation 2 to derive. The result shows that the coefficients of Equation 3 are different under the four ATs. TS and AT have coupling effects on the MCT, MRT and MW of rats.
探讨模拟微重力和不同环境温度下大鼠平均胸温(MCT)、平均直肠温度(MRT)和平均体重(MW)的变化规律。采用- 300大鼠尾悬液(TS)法,在18°C、20°C、23°C和26°C at下模拟7 d的微重力,将TS组与对照组进行比较。每组6只雄性SD大鼠(其中1只验证大鼠)。TS组大鼠的MCT和MRT在四个水平at均升高。在20°C和23°C温度下,MCT和MRT的最大生长速率分别为0.315和0.118。在20°C和23°C的温度下,TS组的MW降低,而在18°C和26°C的温度下,TS组的MW增加。采用线性回归分析对照组(方程1)和TS组(方程2)不同at时MCT、MRT和MW的变化率。在方程1 -方程2的基础上推导出不受其他因素影响的新方程(方程3)。结果表明,在4种工况下,式3的系数是不同的。TS和AT对大鼠MCT、MRT和MW有耦合作用。
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引用次数: 0
Production of Lightweight Concrete Using Corncob Ash as Replacement of Cement in Concrete 用玉米芯灰替代混凝土中的水泥生产轻质混凝土
Pub Date : 2019-03-25 DOI: 10.11648/J.AJCE.20190701.13
Sintayehu Assefa, Mamaru Dessalegn
One of the biggest issues, all over the world is getting affordable house to the community. In developing countries, where it is difficult for most people to satisfy basic needs, construction of modern house is a big challenge. Different ways were tried by researchers and scholars to find alternative construction materials. One of this is replacing the costly construction material of cement with locally available material, especially with those considered as waste. Corncob is an agricultural waste, which is considered as one of binding materials. Very few researchers tried to use corncob ash as a means of producing lightweight concrete. So, this research was aimed to check whether corncob ash is used to produce lightweight concrete by replacing cement as a binding material or not. In order to reach on conclusion, corncob was collected from agricultural farmers and burned in furnace at a temperature of 850°C. The burned ash powder was sieved in order to remove coarser material and replacement of cement was done by 5%, 10%, 15%, 20%, 25%, 30%, and 35% with corncob ash. For each replacement, including control, 3 samples were prepared based on ASTM standards. After curing for 7 and 28 days in curing tank, the weight and compressive strength of samples were checked. Based on the experimental result, as the percentage of corncob ash increase, the weight of cubes decreased and 15% and above corn cob ash replacement makes concrete cubes lightweight. The compressive strength was also decreasing as the amount of replacement increase. However, up to 15% replacement, compressive strength is found within the range of concrete grade requirement.
世界各地最大的问题之一是为社区提供负担得起的房子。在发展中国家,大多数人的基本生活都难以满足,建造现代住宅是一项巨大的挑战。研究人员和学者尝试了不同的方法来寻找替代建筑材料。其中之一是用当地可用的材料,特别是那些被认为是废物的材料取代昂贵的水泥建筑材料。玉米芯是一种农业废弃物,被认为是粘结材料之一。很少有研究人员尝试使用玉米芯灰作为生产轻质混凝土的手段。因此,本研究旨在验证玉米芯灰是否可以替代水泥作为粘结材料来生产轻质混凝土。为了得出结论,从农民那里收集玉米芯,在850℃的炉中燃烧。对燃烧后的灰粉进行筛分,以去除较粗的物料,并用玉米芯灰分别以5%、10%、15%、20%、25%、30%和35%的比例替代水泥。每次替换,包括对照,根据ASTM标准制备3个样品。分别在养护槽养护7天和28d后,对试样的重量和抗压强度进行校核。试验结果表明,随着玉米芯灰掺量的增加,混凝土立方体的重量降低,15%及以上的玉米芯灰掺量使混凝土立方体轻量化。随着替代量的增加,抗压强度也逐渐降低。然而,高达15%的替换,抗压强度是在混凝土等级要求的范围内。
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引用次数: 17
Development of a Self-balanced Rock True Triaxial Compression Instrument 自平衡岩石真三轴压缩仪的研制
Pub Date : 2019-03-08 DOI: 10.11648/J.AJCE.20190701.12
Tang Yanchun, Wang Yue, Liu Ruilong, Zhou Hui, Mao Qingfeng
Based on the analysis of the structure and the performance of similar instruments at home and abroad, a Self-balanced Rock True Triaxial Compression instrument (SRT) was developed. For SRT, complex stress realization, based on three-dimensional stress alone control and change; and the self-balanced structure is adopted on the basis of frame design, which makes the instrument simple and compact; design of lateral composite press plate with embedded rolling roller, the influence of test results on the effect of friction on the side end surface of the specimen under lateral stress constraint can be eliminate effectiveness; The design scheme of transverse double sliding rod is adopted, its validity can be designed by horizontal alignment, and the problem of eccentric compression of specimen can be partly alleviated in horizontal direction. By changing the alkali of the mothed triaxial chamber, both true triaxial and conventional triaxial compression can be tested. Test results of true triaxial and conventional compression of rocks with different lithology were carried out by SRT. The results, such as the deformation and failure characteristics of rock strength in complex stress conditions, have been obtained by SRT, which indicates that the design of SRT is feasible and feasible. The development of this instrument can promote the further development of Chinese rock triaxial testing machine.
在分析国内外同类仪器结构和性能的基础上,研制了自平衡岩石真三轴压缩仪(SRT)。对于SRT,实现复杂应力,仅基于三维应力的控制和变化;在框架设计的基础上采用自平衡结构,使仪器结构简单紧凑;设计内嵌滚轮的侧向复合压板,有效消除侧向应力约束下试件侧端面摩擦对试验结果的影响;采用横向双滑杆的设计方案,通过水平对中来设计其有效性,在水平方向上可以部分缓解试件偏心受压问题。通过改变有孔三轴室的碱度,可以进行真三轴和常规三轴压缩试验。采用SRT对不同岩性岩石进行真三轴压缩和常规压缩试验。通过SRT得到了复杂应力条件下岩石强度的变形破坏特征等结果,表明SRT的设计是可行的、可行的。该仪器的研制可以促进我国岩石三轴试验机的进一步发展。
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引用次数: 1
Concept of Value Engineering and Current Project Management Practice in Ethiopian Building Construction Projects 价值工程理念与埃塞俄比亚建筑工程项目管理现状
Pub Date : 2019-02-27 DOI: 10.11648/j.ajce.20190701.11
Tsigereda Garomsa, Elmer C. Agon, Sintayehu Assefa
In construction projects, when one-program costs more than planned, decision makers are forced to delay or cancel other activity. Value Engineering can play a key role in overcoming such problems by ensuring programs stay within project duration, estimated budget and saving costs. This study was conducted to assess the applicability of value engineering concept and the current management practice of Ethiopian building construction projects. In this study, knowhow of Ethiopian building construction project experts on value engineering principles were studied and the current management practice was examined. In order to gather required information, questionnaire, interview with project managers and archival review was conducted. Data was analyzed both qualitatively and quantitatively. The result of this study shows, main challenges in the project area were: delay in progress payment by owner, poor site management, weak follow up by consultant, and delay in material delivery from contractor side. Almost all experts in the project have no knowledge on the principle of value engineering and has no willingness to implement the principle. The evaluation made using value engineering principle shows the current management practice was more conventional and the industry is still facing delay of projects, cost overrun and poor quality while there are opportunities to minimize such problems.
在建设项目中,当一个项目的成本超过计划时,决策者被迫推迟或取消其他活动。价值工程可以在克服这些问题中发挥关键作用,确保项目在项目持续时间、预算和节省成本之内。本研究旨在评估价值工程概念的适用性和埃塞俄比亚建筑施工项目当前的管理实践。在本研究中,埃塞俄比亚建筑建设项目专家对价值工程原则的知识进行了研究,并对当前的管理实践进行了检查。为了收集所需的信息,我们进行了问卷调查、项目经理访谈和档案审查。对数据进行定性和定量分析。研究结果表明,项目领域的主要挑战是:业主进度付款延迟,现场管理不善,顾问跟进不力,承包商方面的材料交付延迟。项目中几乎所有的专家都不了解价值工程的原理,也没有实施价值工程原理的意愿。利用价值工程原理进行的评价表明,目前的管理实践较为常规,行业仍然面临着项目延迟、成本超支和质量差的问题,而这些问题有机会最小化。
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引用次数: 3
Highway Asset Management Framework for Longevity of Infrastructure – A Case Study for China-Pakistan Economic Corridor 基础设施长寿的公路资产管理框架——以中巴经济走廊为例
Pub Date : 2019-01-05 DOI: 10.11648/j.ajce.20180606.12
Muhammad Irfan, Y. Mehmood, Anwaar Ahmed, Hainian Wang
Pavement management system (PMS) affords objective information and useful data analysis to make consistent, cost-effective, and defensible decisions related to the pavement preservation at network and project level. Pavement functional and structural evaluations using performance indicators such as international roughness index (IRI), surface distress, rutting, deflection data etc. are the key element of PMS. A departure from exiting stand-alone evaluation practices, this research presents project-level functional and structural evaluation and its integration into a PMS framework for more accurate and realistic forecasting of the pavement needs over the analysis period. A case study of an in-service pavement is presented to demonstrate the applicability of proposed framework. Owing to the non-availability of time-series performance data at present, pavement serviceability and structural capacity data before and after of an in-service pavement rehabilitation was explored for overlay treatments (conventional and crumb rubber- modified (CRM) asphalt mixtures) effectiveness analyses. Results of functional evaluation quantified the extent to which CRM improves the functional performance of the pavement, in terms of the drop in IRI. CRM asphalt mixture exhibited relatively superior functional performance in contrast to conventional asphaltic wearing course by a margin of 8% higher drop in IRI, on average. Non-destructive testing technique for pavement structural evaluation using falling weight deflectometer (FWD) data was employed to assess structural capacity of pavements. A computer-aided program was developed for estimation of structure number effective (SNeff) to be used as an input for overlay design using AASHTO empirical method. Moreover, mechanistic-empirical (M-E) design method was employed using evaluation of layer moduli and overlay design (ELMOD) program for overlay thickness design and pavement remaining service life (RSL). Comparison of pre- and post-rehabilitation deflection data endorsed roadbed soil stiffness and structural adequacy. RSL estimated through traffic data (truck load repetitions) validated the results obtained using empirical and M-E methods. Application of KENPAVE program for evaluation of pavement overlay thickness design was also demonstrated by conducting damage analysis. Integrating structural evaluation with functional evaluation into an overall framework of PMS is envisaged to provide systematic and objective procedures for monitoring and evaluating pavement performance, selecting optimal type of treatment and its thickness design.
路面管理系统(PMS)提供客观的信息和有用的数据分析,以在网络和项目层面上做出与路面保护相关的一致的、具有成本效益的和可辩护的决策。采用国际粗糙指数(IRI)、路面破损、车辙、挠度数据等性能指标对路面功能和结构进行评价是PMS的关键要素。与现有的独立评估实践不同,本研究提出了项目级功能和结构评估,并将其整合到PMS框架中,以便在分析期间更准确、更现实地预测路面需求。最后以某现役路面为例,验证了该框架的适用性。由于目前无法获得时间序列性能数据,因此研究了在用路面修复前后的路面使用性能和结构能力数据,以进行覆盖层处理(常规和碎橡胶改性(CRM)沥青混合料)的有效性分析。功能评价结果量化了CRM改善路面功能性能的程度,即IRI下降的程度。与传统沥青磨损过程相比,CRM沥青混合料表现出相对优越的功能性能,平均IRI下降幅度高出8%。采用沉降量偏转仪(FWD)数据无损检测技术对路面结构承载力进行评价。利用AASHTO经验方法,开发了结构有效数(SNeff)估计的计算机辅助程序,作为叠加层设计的输入。采用力学-经验(M-E)设计方法,利用层模量评价和铺层设计(ELMOD)程序进行铺层厚度设计和路面剩余使用寿命(RSL)。修复前后挠度数据的比较支持路基土刚度和结构充分性。通过交通数据(卡车载重重复)估计的RSL验证了使用经验和M-E方法获得的结果。通过损伤分析,论证了KENPAVE程序在路面覆盖层厚度设计评价中的应用。设想将结构评价和功能评价整合到PMS的总体框架中,为监测和评价路面性能、选择最佳处理类型及其厚度设计提供系统和客观的程序。
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引用次数: 0
A Logistic Model Predicting Occurrence Probability of Debris Flow 泥石流发生概率的Logistic预测模型
Pub Date : 2019-01-01 DOI: 10.11648/j.ajce.20190701.14
J. P. Wang
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引用次数: 0
Improvement of Strength and Consolidation Properties of Clayey Soil Using Ceramic Dust 陶瓷粉尘对粘土强度和固结性能的改善
Pub Date : 2019-01-01 DOI: 10.11648/j.ajce.20190702.11
Md. Akhtar Hossain
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引用次数: 1
Expanding Understanding on Attributes of Innovation Champions: Firms and Individual Perspectives of Professional Quantity Surveying Firms 拓展对创新冠军属性的理解:专业工料测量公司的企业与个体视角
Pub Date : 2018-12-28 DOI: 10.11648/J.AJCE.20180606.11
Owusu-Manu De Graft, A. Prince, Edwards David John
Quantity Surveying Profession (QSP) globally has undergone significant revolution and has embraced career pathways in providing excellent services within and outside the construction industry. The QSP adapting to the changes in the construction industry, and innovating to remain competitive has allowed them to adopt some specific attributes which makes them process innovation champions. Identifying these characteristics of the QSP for appreciation and implementation gave the purpose for this studies. Drawing from quantitative research approach, and using purposive and convenience sampling technique, data was collected and analysed. The study adopted descriptive statistics, Relative Importance Index (RII) and cross tabulations as its tools of analysis. After analysis, the outstanding attribute of innovative Quantity Surveying (QS) firms’ worthy of emulation were good managerial skills and capability, followed by team learning and competency. On individual perspective, all the identified variables were outstanding characteristics with interaction with others in the workplace ranking first, followed by open to experience while acting out of curiosity ranked last. Findings of this study could assist in understanding the set of characteristics which makes firms innovative. The identified attributes would also help other project teams in the construction industry to increase their innovativeness and output when they are examined, understood and implemented.
工料测量专业(QSP)在全球范围内经历了重大变革,并在建筑行业内外提供了优质的服务。QSP适应建筑行业的变化,通过创新保持竞争力,使他们能够采用一些特定的属性,使他们成为流程创新的冠军。确定QSP的这些特征以供欣赏和实施是本研究的目的。采用定量研究方法,采用目的性和便捷性抽样技术,对数据进行了收集和分析。本研究采用描述性统计、相对重要性指数(Relative Importance Index, RII)和交叉表作为分析工具。经分析,创新工料测量公司值得效仿的突出属性是良好的管理技能和能力,其次是团队学习能力和胜任力。从个人角度来看,所有确定的变量都是突出的特征,在工作场所与他人的互动排名第一,其次是开放的经验,而出于好奇心的行动排名最后。本研究的发现有助于理解企业创新的一系列特征。确定的属性也将有助于建筑行业的其他项目团队在检查,理解和实施时增加他们的创新和产出。
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引用次数: 7
Seismic Response Evaluation of High-Rise Building with and Without Fluid Viscous Damper 有无流体粘性阻尼器的高层建筑地震反应评价
Pub Date : 2018-12-24 DOI: 10.11648/j.ajce.20180605.15
Khalil Yahya Mohammed Almajhali, Bin Xu, Qingxuan Meng
The major lateral load of the high structures is the earthquake load. In the high rise buildings, the structural response increases exponentially in response to earthquake load. Therefore, the damping has significant function in design of Earthquake Resistant High Structures, which can decrease the response of the structure when exposed to lateral loads. The energy produced by earthquake will be absorbed by these devices and the load acting on the main structure of the building will reduce significantly. The fluid viscous dampers are used to dissipate energy and lessen the response of reinforced concrete buildings. The main function of structure is to carry the lateral loads and transmit them well to the foundation. The lateral loads enjoined on the structures are dynamic in nature, which cause vibrations in the structure. In the current study, the responses of the structures having square plans with different cross-sections are analyzed by the software ETABS 2015 based on the consideration of Fluid Viscous Damper. The results of numerical examples show that fluid viscous damper (250) can reduce the response of the structures effectively, including the base shear of the buildings, and the structures with square columns performs perfect and have good earthquake resistant characteristics when compared to structures with rectangular columns regardless of the flooring plan.
高层结构的主要侧向荷载是地震荷载。在高层建筑中,结构对地震荷载的响应呈指数级增长。因此,阻尼可以降低结构在侧向荷载作用下的响应,在抗震高层结构设计中具有重要的作用。地震产生的能量将被这些装置吸收,作用在建筑物主体结构上的荷载将大大减少。采用流体粘性阻尼器对钢筋混凝土结构进行耗能和减振。结构的主要作用是承受横向荷载并将其良好地传递给基础。施加在结构上的横向荷载是动力荷载,它会引起结构的振动。本研究在考虑流体粘性阻尼器的基础上,利用ETABS 2015软件对不同截面的方形平面结构的响应进行了分析。数值算例结果表明,流体粘性阻尼器(250)能有效地降低结构的响应,包括建筑物的基底剪力,无论楼面布置如何,方柱结构都比矩形柱结构表现更好,具有良好的抗震性能。
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引用次数: 1
期刊
American Journal of Civil Engineering
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