针对混凝土结构基本原理课程传统教学模式中存在的主要问题,结合南京理工大学的教学实践,对微课教学模式在该课程建设中的应用展开研究.通过重塑既有教学内容,选择合适知识点,合理设计教学内容,为学生准备"短、平、快"的"碎片化"的微课(程)资源,供其灵活自主地按需选择学习,增加学生的课程参与度并提高教学效率,使学生在有限的学时内获得更多的专业知识,取得了良好的教学效果,为其他土木工程专业课程建设提供了参考与借鉴.

针对高校土木工程专业实践教学环节存在的诸多问题,以南京理工大学土木工程专业为例开展研究.首先,分析了高等教育所面临的变局,提出本科人才培养方案是改革的破局点,实践教学是本科人才培养链条上至关重要的一环;其次,分析了高校土木工程专业实践教学环节存在的问题;最后,介绍了南京理工大学土木工程专业基于"321"人才培养模式的四层次递进式实践教学体系,并详细阐述了课程思政融入点、毕业要求支撑关系、考核方式改革、教学内容更新、线上线下混合式实习平台、青年教师工程实践保障机制等改革措施.

针对高校课程思政教育存在的诸多问题,文章以混凝土结构基本原理课程为例开展研究.在学情分析的基础上,通过教学方法的创新、教学与科研相结合、思政教学点的优化设计等手段,抓准抓实课程思政,积极推进一流本科课程建设;构建了以学生为中心的课程教学模式,实现了知识、能力、素质、情怀有机融合的教学理念.

为适应当前国家新基建形势对土木工程专业人才的新要求,南京理工大学土木工程专业对本科人才培养模式进行针对性的改革.在学校"321"本科人才培养新方案的总体框架下,研究本专业人才培养模式改革的四大主要措施,构建"基础+进阶"课程体系、设置学科交叉融合课程、构建递进式实践教学体系、设置专业选修课程模块.在此基础上,详细阐述南京理工大学土木工程专业在"321"本科人才培养模式下具体培养目标,预期实现本专业人才培养适应于国家基础设施建设发展需要,为相关院校专业修订人才培养方案提供参考借鉴.

为研究分离式实心板梁桥的跨越能力和承载特性,依据现行规范提出分离式实心板梁桥的设计框架并进行典型桥例的结构计算.选取跨径、桥宽、主梁间净距和主梁截面尺寸等关键参数,基于MATLAB程序对该桥型进行结构参数分析,探究其受力性能和跨越能力.基于塑性铰线理论对潜在破坏模式进行承载性能分析.研究表明,采用国内现行规范设计的桥例基本满足该桥型的使用性能和承载性能要求.正常使用极限状态正截面抗裂性验算和短暂状况应力验算往往是该桥型结构设计的关键条件.随着主梁间净距的减小和主梁高度的增加,分离式实心板梁桥的跨越能力有所增强.采用预应力筋端部脱粘技术可以提高该桥型的设计跨径8％～15％,并降低梁端偏心布置的预应力筋产生的弯曲应力.

In recent years, Very Large Floating Structures (VLFS) technology has attracted much attention for its sustainable and eco-friendly approach in creating land from the sea. Owing to the massive size, VLFS are usually fabricated as a number of floating modules in shipyards, towed to site and connected on sea. To ensure the functionality of such connected VLFS, effective connector systems are essential. The connector system must address issues related to the relative motion between adjacent modules and be able to sustain forces as a result of wave motion. This paper presents a critical review on the research and development in connector systems for modularized VLFS. Various design concepts for connector systems are first categorized and their working principles outlined. Research studies on hydroelastic analysis of VLFS and the effectiveness of connector systems in reducing the hydroelastic responses and internal stress resultants in connectors are also reviewed. In addition, potential technical challenges on the determination of connector stiffness in practical designs are discussed. Finally, some recommendations and suggestions for future practice are provided.

The debate on whether the creep failure is induced by a stress threshold or a strain threshold is studied on several soils in this paper with a power law model and a normalization curve. The analysis indicates: (a) the creep failure is based on a critical strain, which is obtained with a normalization curve; (b) the time to the creep failure is very long for a low stress level or a low creep exponent; (c) for a given time to the creep failure, the strain threshold could be converted to a stress threshold, and variable stress thresholds will be calculated for different times given to the creep failure; (d) the creep behavior of various materials could be compared with the normalization curve and the power law model.

Large floating structures such as platforms, breakwaters and piers, have been constructed in many countries in coastal areas in a bid to increase land space. Due to construction ease and operational flexibility, these facilities are commonly consisted of relatively small floating units that are subsequently connected on sea. This paper first describes box-like structural systems for concrete floating structures. Finite element (FE) analyses are then performed to assess the structural performance of concrete floating structures when subjected to self-weight, imposed live load, hydrostatic pressure and buoyancy force. The effects of geometrical shapes, cell numbers and slab thickness on the structural performance of box-like floating modules are investigated. Results indicate the need to provide prestressing steels so as to prevent cracking in the concrete modules. Besides, material requirements for different configurations were compared to provide the most economical solution for box-like concrete floating units. Furthermore, global responses of modular multi-purpose floating structures with different geometrical shapes were investigated via hydroelastic analyses using self-developed hybrid boundary element (BE) – FE code. Global flexural stresses are found to be quite high for rigidly-interconnected large floating structures due to regular wave loadings, especially when the geometrical aspect ratio becomes large. The use of hinge joints is effective in reducing bending moments but it relatively increases the vertical deflections. A trade-off should be considered between internal loads and structural motions in the conceptual design of large floating structure system.

针对混凝土结构基本原理课程传统教学中的"痛点"问题,结合教学实践,确定了"力"为主线、"实"为过程、"能"为目标,实现知识、能力、素质、情怀有机融合的教学创新思路.教学团队在实践中引入IDEA StatiCa软件,学生通过模拟仿真分析,建立结构受力过程的直观形象,突出了课程的创新性;采取教师讲授、生讲生评、边讲边练、案例分析、课堂翻转等综合教学方法,增强了课程的高阶性;构建了全方位全过程考核评价体系,提升了课程的挑战度,达到了学生概念能理解、知识能掌握、方法会应用、设计能完成、学习有收获的教学效果.

为深入揭示无支撑置换混凝土加固过程中剪力墙的受力变化规律,对某剪力墙住宅结构无支撑置换加固施工进行全过程监测.基于ABAQUS有限元分析软件,采用生死单元、等效升温以及添加场变量的方法实现剪力墙施工全过程模拟.结合施工监测数据及有限元模拟结果分析了置换剪力墙及与置换剪力墙相连的梁、楼板受力变化过程;最后给出了考虑应力重分布后,无支撑分段置换墙体正截面受压承载力计算方法.结果表明:有限元模拟方法能有效模拟混凝土无支撑置换加固施工过程;由于剪力墙分段拆除和置换,墙体出现了应力重分布现象,且应力重分布程度与墙体分段施工顺序有关;应力重分布会引起墙体洞口处出现应力集中,但应力集中对加固效果的影响较小,同时还会影响与置换剪力墙相邻的连梁、楼板结构的受力,导致该处应力增加;建议对剪力墙结构进行无支撑置换加固时,有必要通过分段优化设计和受压承载力复核控制应力重分布的影响.

为推动新型分离式空心板梁桥的工程应用,提出针对该桥型的荷载横向分布系数计算方法.选取主梁间距、桥梁跨径、桥宽和梁高作为影响桥梁横向受力性能的参数,采用ABAQUS有限元软件计算不同参数组合的分离式空心板梁桥结构在单车道和多车道荷载作用下的弯矩和剪力横向分布状况,探究关键参数对荷载横向传递的影响规律;通过非线性回归分析法拟合得到弯矩和剪力横向分布系数在不同荷载工况下的计算公式.实桥算例验证结果表明,该方法计算结果可信,具有一定的安全度,能够较好地满足工程设计的要求.

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It is very common in the ballasted track system that sleepers are not well supported by the ballast materials due to the uneven settlement of the ballast under repeated train passage. These unsupported track elements are often termed as hanging sleepers and they can lead to undesirable effects due to increased dynamic response of the train-track system, especially when the speed of the train is high. In this paper, we present a computation scheme in conjunction with the moving element method for the analysis of high-speed train-track dynamics accounting for hanging sleepers. The proposed computational scheme will be first verified by comparison with available analytical results. The dynamic response of a high-speed train traveling on a ballasted track considering unsupported sleepers is next investigated. Various factors affecting the response of the high-speed rail system including the speed of the train, the number of hanging sleepers and the pattern of the hanging sleepers will be examined and discussed.

In this paper, a computational scheme in conjunction with the moving element method has been proposed to investigate the dynamic response of a high-speed rail system in which the discrete sleepers on the subgrade support the railway track. The track foundation is modeled as a beam supported by uniformly spaced discrete spring-damper units. The high-speed train is modeled as a moving sprung-mass system that travels over the track. The effect of the stiffness of the discrete supports, train speed, and railhead roughness on the dynamic behavior of the train–track system has been investigated. As a comparison, the response of a continuously supported high-speed rail system that uses a foundation stiffness equivalent to that of a discretely supported track has been obtained. The difference in results between the “equivalent” continuously supported and the discretely supported high-speed rails has been compared and discussed. In general, the study found that a high-speed train that travels over a discretely supported track produces more severe vibrations than that travels over a continuously supported track of equivalent foundation stiffness.

This paper is concerned with a numerical study on the dynamic response of a high-speed rail (HSR) system subjected to unsupported sleepers using the moving element method (MEM). A three-phase computational scheme in conjunction with the MEM is proposed to account for the motion of the unsupported sleepers in relation to the truncated rail segment in the moving coordinate system. The accuracy of the proposed computational scheme is examined by comparison with available analytical results in the literature and against the finite element method using commercial software. A parametric study is conducted using a computational model consisting of a 10-degree of freedom train model and a three-layer ballasted track model to investigate the effect of unsupported sleepers on the dynamic response of the HSR system. Various factors affecting the response of the HSR system, including the speed of the train, the number of unsupported sleepers and the distance between the unsupported sleepers, are examined and discussed.

Prestressed concrete floating structures have been used for over a century with notable success in various parts of the world. However, there still exist issues related to the analysis and design, and the service performance of concrete floating structures. This paper highlights the design concepts, material behavior, analysis approaches and structural systems for floating prestressed concrete structures deployed in shallow waters. Material and design requirements related to prestressed concrete floating structures in particular are reviewed and potential technical challenges are identified. Moreover, some recommendations and suggestions are summarized as a guide for future practice.

Prestressed concrete (PC) cylindrical tanks are used in industrial applications as liquid containing facilities, and are commonly constructed as base-supported structures with their associated foundations poured in place. In land-space constrained countries, however, it becomes viable to construct such facilities on sea as floating structures. This study deals with the design of an innovative self-stabilizing floating fuel storage tank. For this new type of fuel storage facility, the self-weight of the tank and the in-fill fuel are automatically balanced by the buoyancy force, and there is no need for vertical supporting foundations. Furthermore, the hydrostatic pressures on the tank wall due to outside sea water and in-fill fuel balance each other to a great extent, leading to significant reduction in material consumption and construction costs. Due to the absence of specific guidelines and engineering practices, it remains unknown whether PC floating self-stabilizing fuel storage tanks are applicable in the offshore environment. In this study, a comprehensive stability analysis was first carried out to determine the geometrical dimensions for tanks of different capacities varying from 5,000 m3 to 15,000 m3 in order to meet the operational requirements. Finite element (FE) models were then developed to assess the structural performance of a selected tank of 12,500 m3 capacity when subjected to self-weight and hydrostatic pressure. Based on the analytical results, potential technical challenges were identified and design recommendations were further provided.

A new class of spread slab beam bridges has recently been developed and implemented in Texas. Due to the absence of appropriate design guidelines, moment and shear design actions have been based on those used for spread box beam bridges; however, their applicability remains in question. To develop new criteria, the load distribution behavior of this new bridge system is investigated. Comprehensive static and dynamic tests are performed on an in-service spread slab beam bridge located on US 69 in the city of Denison, Texas. Various experimental methods are used to infer the moments and shears resisted by individual beams that arise from a heavily loaded truck. Experimentally derived load distribution factors (LDFs) are compared with refined finite element model predictions. Satisfactory agreement is obtained. The experimental test results indicate that the existence of a sidewalk and guardrail markedly stiffens the structure leading to higher than expected moment values. The observed bridge responses under moving dynamic loads exceed the present design specifications impact factor of 33%. Thus, for service load design it is recommended the allowable tensile stress be slightly reduced. (C) 2016 Elsevier Ltd. All rights reserved.

The Texas Department of Transportation (TxDOT) uses precast prestressed concrete slab beams in a side-by-side configuration for short-span bridges in low-clearance areas. To reduce costs, a new bridge type called a spread slab beam bridge was recently developed using the same concept as spread box beam bridges in which the beams are spaced apart. A full-scale spread slab beam bridge was constructed and tested under static and dynamic vehicular loads to evaluate constructability and structural performance. The load-distribution behavior was investigated through field testing, and experimental live-load distribution factors (LLDFs) were evaluated using alignments that provided the most adverse loading cases. The measured response provides detailed experimental data to validate computational modeling techniques for this new class of bridge systems. Research findings show that spread slab beam systems provide a viable construction method for short-span bridges, and that the desired performance was achieved for in-service loading. During field testing, the beam live-load deflections were within the design limits, and no significant cracking or reduction in the overall stiffness of the bridge was observed.

A new bridge type called a spread slab-beam bridge was developed recently by using the same concept as that used for spread box beam bridges, in which the beams are spaced apart. This paper presents an evaluation of the new bridge system in terms of design and constructability and investigates the challenges encountered during construction. Forty-four bridge geometries were designed by using standard Texas DOT (TxDOT) slab-beam types to determine the feasible design space. One of the most aggressive geometries with widely spaced slab beams was constructed at full scale. On the basis of the research findings, it was concluded that spread slab beams with a topped panelized deck provide a viable construction method for short-span bridges. Results of a shear-design check show that the standard interface shear reinforcement must be doubled for the first quarter of the span length for more aggressive designs. Larger-than-expected camber of the precast slab beams might cause construction challenges and delays. A 30% increase in standard camber estimates can be used for construction purposes. High differential temperatures together with drying shrinkage might lead to early-age longitudinal deck cracking. Care should be taken during concrete curing to avoid factors that contribute to large temperature changes in the deck.