Slab-on-Grade versus Framed Slab

This paper presents comprehensive and practical engineering review (not mathematics or computer science paper) of the observed behavior of the two types of slabs that have been used for the bottom floor slabs, at grade and underground, of buildings in the United States and overseas. The typical design of the slab-on-grade (SOG) built in the United States is described. The design requires only nominal reinforcing steel, but modern day design also requires ground preparation and improvement as necessary, including underslab perforated drainage pipe network embedded in the granular subbase, riser pipes, and a series of pumps. Sealing at all slab isolation joints and waterproofing membrane or water barrier system are provided for water tightness. The framed slab is supported directly on the building framing and on the building foundation. The design can accommodate the soil and underground water pressure and in itself is watertight as the slab is cast monolithically with the structural walls and footings. The behavior of the SOG depends so much on the behavior (soil properties) of the soil strata on which the slab is resting on. It is sensitive to the variation of the soil conditions at and around building foundations, leading to uneven bumpy and cracked slab and leaking basement. These were demonstrated in the report of short- and long-term performances of various projects in Thailand and United States in the past 25 years. The paper refers to various analysis and design techniques that may be used to improve the design of both the SOG and the framed slab for serviceability and economy. It is concluded that both types of slabs may be selected to suit the functions and serviceability requirements of the buildings. The SOG requires less concrete and reinforcement than those for the framed slab counterpart, but when all other factors are considered including additional underslab drainage and pump system, operating, and long-term performance and maintenance, the overall costs of both slabs may not be far apart, yet the performance and integrity of the framed slab will certainly be superior.     

不同市场条件下金属露天矿分期方案动态优化

不同市场条件下金属露天矿分期方案动态优化有关于金属露天矿分期方案动态优化的整体方案的设计与实施,是结合采选联合优化的一部分内容,针对地下采选一体化实现的露天金属矿采选联合优化,露天金属矿采选联合优化也是与金属露天矿分期方案动态优化相关,对于采选联合优化的选矿过程都是存有金属露天矿分期方案动态优化的内容,这就需要施工人员和设计者在涉及到井下的内部转化以及其他金属露天矿分期方案动态优化部分的过程中能够对于一些采选联合优化的内涵做出详尽的了解和分析。比如地下采矿中通常采用一体化设计,但是这种设计的缺点就是难以进行露天金属矿采选联合优化,但是对于矿山开展的试验性研究工作还是有利的,能够实现按空间位置的一体化是采选联合优化的内涵及发展历程的关键。     

以数字基建支撑钢铁行业内涵式发展

 为了研究数据在钢铁行业的生态化利用问题,介绍了中国钢铁行业发展面临的新形势,以及新发展阶段对钢铁企业的新型能力要求,阐述了钢铁行业存在的问题及发展趋势,分析了钢铁行业数据资源特点及数字赋能基础,数据要素与土地、劳动力、资本、技术等传统生产要素不断交叉融合,从提升企业核心竞争力、优化行业资源配置、支撑政府行业治理3个层面,总结了钢铁行业数据发力的重点领域,提出以基于区块链的“数字基建”构建行业新型信用体系,支撑钢铁内涵式发展。     

铜萃取电积厂的设计探讨

根据长期的设计工作经验和生产实践,针对铜萃取电积工艺设计的相关问题进行探讨,并提出适用的设计方案。其中,工艺部分包括铜萃取电积工艺方案的确定、萃取剂的选用、相连续的控制等;设备及厂房布置部分探讨了设备和管路的适宜材质,溶液池容积和结构形式、设备选择和厂房布置方式;根据车间生产介质的性质采用相应的消防方式;最后介绍了该工艺的投资成本及技术经济指标。     

Analysis of Arch Dams Using Coupled Trial Load and Block Element Methods

This paper presents the use of the trial load method and the block element method with elastoviscoplastic discontinuities for analysis of arch dams. The arch dam is considered as an arch-cantilever system and the foundation as a block element system. With the displacement compatibility condition at the contact surface of the dam and the foundation (including abutment), the governing equations of the arch dam and foundation are established. These methods are used for the analysis of the double curvature arch dam with complex geology conditions of the Xiaowan Hydroelectric Project in China. The deformation and stress states in both the dam body and the foundation are determined. Furthermore, the stability safety factors of the foundation and the abutment are calculated at the same time, which allows for an optimal design of the arch dam considering the strength, the deformation and the stability of the dam and foundation.     

火炮身管用钢现状及发展趋势

火炮身管用钢决定了身管类武器的使用性能，影响火炮的作战持续性与机动性。通过对国内外火炮身管用钢合金成分体系、制造工艺流程、材料主要性能指标总结分析，指出当前国内外炮钢主要牌号、性能水平以及存在高温性能不足的问题。通过调研国内外火炮用钢最新研究成果以及身管武器整体技术需求，总结和展望了火炮身管用钢的研究现状和发展趋势，针对大口径火炮研制高强韧炮钢以减轻壁厚和质量，针对中小口径速射火炮研制耐烧蚀性能炮钢以提高使用寿命。     

RC Slabs Strengthened with Prestressed and Gradually Anchored CFRP Strips under Monotonic and Cyclic Loading

This paper presents the test results of reinforced concrete slabs strengthened with prestressed and gradually anchored carbon fiber–reinforced polymer (CFRP) strips under monotonic and cyclic loading. To take full advantage of the externally bonded CFRP technique, it is beneficial to apply the laminates in a prestressed state, which relieves the stress in the steel reinforcement and reduces crack widths and deflection. The aim of the monotonic tests was to determine the strengthening efficiency of the new prestressing technique and to investigate serviceability and ultimate states. The cyclic tests were performed to identify the fatigue behavior of the strengthened slabs and to investigate the influence of long-term cyclic loading and elevated temperature on the bond properties of the prestressed CFRP laminates and the ductility and flexural strength of the strengthened slabs. A nonlinear analytical model of reinforced concrete members strengthened with passive and prestressed CFRP strips under static loading is proposed in the paper. A comparison of the experimental and predicted results reveals an excellent agreement in the full range of loading.     

Time for Development of Internal Erosion and Piping in Embankment Dams

A method is presented for the approximate estimation of the time for progression of internal erosion and piping, and development of a breach leading to failure in embankment dams and their foundations. The method accounts for the nature of the soils in the dam core, the foundation, and the materials in the downstream zone of the dam.?Guidance is also provided on the detectability of internal erosion and piping, taking account of the mechanism of initiation, continuation, and progression to form a breach, for internal erosion and piping in the embankment, the foundation and from the embankment to foundation.?It is shown that in many dams which have poor internal erosion and seepage control and are constructed mainly of earthfill, the time for potential development of piping is short, and for these dams continuous monitoring of seepage or surveillance would be needed to detect the piping in time to give warning of possible failure, and to give time to attempt intervention to prevent the failure.     

高炉炼铁数据缺失处理研究初探

针对高炉炼铁过程中的数据缺失问题,提出以单维结合多维的系统化数据填补模式。总结并阐述数据缺失填补办法的发展现状以及优劣势比较。在此基础上,通过对河北某钢铁厂的实际高炉生产数据进行分类比较,并结合填补办法的优缺点,针对高炉炼铁数据提出一套以简单统计类办法、线性插值法、机器学习法等多种办法相结合的方案,以实现高炉数据的深度整合及处理,满足数据挖掘工作的供数需求。同时选取了炉顶温度、氧气管道温度作为数据样本,利用临近点中间值法、临近点均值法、线性插值法、Adaboost算法等对样本数据进行了填补且填补效果较为理想,充分验证了方案的可行性。     

VDC and the Engineering Continuum

In this paper, we provide a brief overview of the historical underpinnings of the design-construction industry and the development of design engineering and construction engineering as independent but related subdisciplines of civil engineering. The effects of the first and second generation of computer tools on design engineering are identified. The complementary and evolving definitions of construction engineering and design engineering are examined, specifically in the context of structural design engineering activities and deliverables and the corresponding construction engineering activities and deliverables. The concept of an “engineering continuum” is introduced, and the process is recast in light of that concept. Several case studies are used to examine the promise of third generation design-construction computing technologies such as virtual design and construction and their potential beneficial impact on the cost and schedule of the typical design-construction project. Refinements to the definitions of construction and design engineering that have the potential to maximize the benefits of third generation technology are proposed with an eye toward the form of fourth generation computing technologies that are on the horizon.