Mechanical model for controlling floor heave in deep roadways with U-shaped steel closed support

Open U-shaped steel arch supports are commonly used in large-section static-pressure roadways in coal mines that are more than 900 m deep;however,it is very difficult to control floor heave of roadways.In this paper,a U-shaped steel closed support with an inverted U-shaped steel arch in the floor is proposed as a method for improving the support effect of the surrounding rock during the process of floor heaving.This research established a mechanical model for the U-shaped steel closed support,and determined the reaction forces at the connection of a camber angle.Using the limit load method calculated the critical buckling load of the inverted U-shaped steel arch,and use of a strength check method tested the strength of the U-shaped steel material.A numerical simulation was conducted using the finite difference software FLAC3 D.The simulation results show that the U-shaped steel closed support is able to control the floor heave of roadways,which is successfully used in the West 11-2 development roadway of the Zhuji Mine in the Huainan mining area in China.The cumulative floor heave over two years was less than50 mm.

Seismic strengthening of reinforced concrete columns damaged by rebar corrosion using combined CFRP and steel jacket

In order to study the effectiveness of combined carbon fiber-reinforced polymer （CFRP） sheets and steel jacket in strengthening the seismic performance of corrosion-damaged reinforced concrete （RC） columns, twelve reinforced concrete columns are tested under combined lateral cyclic displacement excursions and constant axial load. The variables studied in this program include effects of corrosion degree of the rebars, level of axial load, the amount of CFRP sheets and steel jacket. The results indicate that the combined CFRP and steel jacket retrofitting technique is effective in improving load-carrying, ductility and energy absorption capacity of the columns. Compared with the corrosion-damaged RC column, the lateral load and the ductility factor of many strengthened columns increase more than 90% and 100%, respectively. The formulae for the calculation of the yielding load, the maximum lateral load and the displacement ductility factor of the strengthened columns under combined constant axial load and cyclically increasing lateral loading are developed. The test results are also compared with the results obtained from the proposed formulae. A good agreement between calculated values and experimental results is observed.

Calibration of LRFD Format for Steel Jacket Offshore Platforms in China Offshore Area(1) :Statistical Parameters of Loads and Resistances

The statistical characteristics and parameters of loads and resistances are systematically studied for the development of probabilistic limit state design method for steel jacket offshore platforms in the China offshore area. The mean value, standard variance and distribution pattern of resistances and loads in different base perieds are presented. The statistical parameters of structural member resistance, self-weight, deck live load, and environmental loads such as wind, wave, current and ice, which are drawn on a large amount of observatian data of offshore environmental factors, and the design data of platforms in China Bohai Sea form the data set, providing a necessary basis for the calibration of load and resistance factors to realize the reliability-based design of jacket platform structures.

A new bracing system for improvement of seismic performance of steel jacket type offshore platforms with float-over-deck

In this paper, the seismic response of a newly designed steel jacket offshore platform with a float over deck （FOD） system in the Persian Gulf was investigated through incremental dynamic analysis. Comparison of incremental dynamic analysis results for both directions of the platform shows that the lateral strength of the platform in the float over direction is less than its lateral strength in other direction. Dynamic characteristics measurement of a scale model of platform was also performed using forced vibration tests. From experimental measurement of the scaled model, it was observed that dynamic characteristic of the platform is different in the float over direction compared to the other direction. Therefore, a new offshore installed bracing system for the float over direction was proposed for improvement of seismic performance of this type of platform. Finally, the structure with the modified system was assessed using the probabilistic seismic assessment method as well as experimental measurement of its dynamic characteristics. It was observed that the proposed offshore installed bracing system improves the performance of platforms subjected to strong ground motion.

Calibration of LRFD Format for Steel Jacket OffshorePlatform in China Offshore Area(2): Load, Resistance and Load Combination Factors

Adopting the load and resistance factor design format, the design method for steel jaeket platform structures is developed. Firstly, the limit state equations and design format for steel jacket platform structures are introduced. Then, the ratio of live load effect to dead load effect is estimated. The target reliabilities for design of offshore structures in China offshore area are calibrated by past practice in API RP2A-WSD code. The load and resistance factors are optimized by minimizing the difference within the target reliability and the resulting reliability over the range of load effect ratios. Considering the concurrence of different loads, load combination factors are obtained through an optimization process, and the relation between the load combination factor and load correlation coefficient is established. Finally, the design formulae for steel jacket structures in China offshore area are recommended.

基于X-steel的海洋结构物的重量控制

自升式钻井平台和大型导管架拖拉装船,钻井平台的下水和平衡实验,以及大型导管架海上安装的特殊要求,都对重量和重心提出了严格的要求。本文以自升式钻井平台和大型导管架的重量控制为例,简要的阐述重量控制的流程,以及在X-steel软件辅助下,获得海洋结构的重量和重心的方法。

Dynamic performance of angle-steel concrete columns under low cyclic loading-I:Experimental study

This paper describes low cyclic loading testing of nine angle-steel concrete column （ASCC） specimens. In the tests, the influence of the shear-span ratio, axial compression ratio and shear steel plate ratio on the hysteretic behavior, energy dissipation, strength degradation, stiffness degradation, skeleton curve and ductility of the ASCCs is studied. Based on the test results, some conclusions are presented. The P-A and sectional M -φ hysteretic models for the ASCCs are presented in a companion paper （Zheng and Ji, 2008）.

Improvement of Technological Solutions for Sheet Piling Walls Made of U-Shape Piles

As it is evident from the practice of construction and maintenance of thin retaining walls, the degree of developing of frictional forces in interlock connections of steel sheet U-shape piles essentially influences the realization of the values of geometric characteristics of the piles cross-section （the moment of inertia and the section modulus） reduced to the length unit of the construction. The article offers new and simple solutions for realization and economically effective technological approaches to provide joint work of the sheet piles being considered, which improve the adequacy of design and reliability of maintenance of thin retaining walls.

南海流花11-1油田二次开发工程方案及关键技术

流花11-1油田区域水深约300~330 m,油田于1996年投产,采用水下设施+半潜式平台+FPSO方式开发,但由于设施老化,面临进入退役状态。考虑该油田还有较大的开发潜力,以经济有效开发为目标,对流花11-1油田二次开发方案开展了详细研究,确定了深水导管架平台+圆筒型FPSO的开发模式;针对南海最深水导管架(“海基二号”)、首次应用的圆筒型FPSO(“海葵一号”)设计建造面临的问题展开了系统研究,形成了深水导管架平台设计、420 MPa级高强钢应用与平台建造安装以及圆筒型FPSO的主尺度确定、舱室设计、系泊方案、外输方案等多项关键技术;为进一步降低投资,对流花4-1油田回接管缆利旧可行性及方案进行了研究。新技术应用推动了流花11-1油田的二次开发,对南海深水油田开发,尤其是边际油田开发具有较强借鉴意义。

国产S420超高强钢在深水导管架的应用风险分析及应对措施

S420高强钢由于具有高强度、较好的抗断裂韧性、抗疲劳性能等优点,与传统导管架用普通钢材相比,其大规模应用在深水导管架,可以大大减少钢材使用量,有效减轻导管架的总体重量,降低开发成本。目前,国产S420超高强钢并无大规模应用在深水导管架上的先例,其实际的应用效果还无法评估,因此存在一些潜在风险。文章从应用风险及应对措施方面进行探讨,旨在为后续其在导管架平台大规模应用提供可借鉴经验。

超大型深水导管架钢桩建造和装船新技术

介绍超大型深水导管架钢桩的基本信息及其建造和装船传统技术。详细阐述超大型深水导管架钢桩建造和装船新技术,包括钢桩分段预制、钢桩分段整体接长、钢桩打包和钢桩装船等方面。新技术可减少超大型深水导管架钢桩的作业线能力升级和地基改造等需求,并大幅提高接长效率和装船效率。

钢筋混凝土桥墩震后修复技术研究综述

介绍了近几次破坏性地震中钢筋混凝土桥墩的典型震害,总结了国内外利用FRP材料、钢套管、狗骨式杆等新型建筑材料对发生弯曲破坏、剪切破坏、纵筋搭接破坏以及空心截面桥墩的震后修复技术。研究表明,采用合适的修复方案,可以对地震损坏的桥墩进行成功修复,使其承载力和延性得到较好的恢复。文中提到的桥墩震后修复方案可为地震、火灾、爆炸以及腐蚀老化后遭受损坏的钢筋混凝土结构的修复提供参考。

钢套管再生混凝土加固钢筋混凝土柱偏压性能

为达到绿色建筑的目的,提出采用钢套管再生混凝土加固钢筋混凝土柱的思路,并完成1个未加固柱、3个加固柱的轴压试验以及8个加固柱的偏压试验.结果表明:采用钢套管再生混凝土加固后,试件偏压承载力及变形性能均有显著提高,各试件平均相对承载力提高倍数达1.12倍;再生粗骨料取代率对加固试件偏压承载力的影响不明显,而偏心较大时钢管中部截面应变随取代率的提高呈微弱增长;原柱初始应力的存在使得加固试件承载力峰值提前出现,且对其变形产生不利影响;偏心程度对加固试件的影响和普通钢管混凝土类似,随偏心距的增大,试件的承载力降低而钢管受压侧应变增大,且这种规律有随粗骨料取代率增加而增强的趋势.最后,通过对比国内外不同规范和学者提出的公式,采用EC4规范计算所得结果与钢套管再生混凝土加固柱偏压承载力试验结果吻合较好.

地震作用下的导管架海洋平台结构动力优化设计研究

把导管架海洋平台看作钢框架结构,并把优化方法用于结构的抗震设计中。以结构的总重量最小为优化目标,导管的平均直径和壁厚作为设计变量,考虑强度、刚度和稳定等约束条件。通过渤海BZ28 1油田储油平台为例进行了计算,计算结果表明,此方法对海洋平台的设计具有一定的参考意义。

预应力钢板箍加固高轴压比框架柱抗震性能研究

提出一种采用预应力钢板箍对钢筋混凝土矩形截面柱进行抗震加固的方法。进行9个采用预应力钢板箍加固的高轴压比RC短柱试件的低周反复加载试验。主要研究轴压比n、箍板特征值η、预应力水平α等参数对采用预应力钢板箍加固技术加固混凝土矩形截面柱的抗震性能的影响。通过试验检验了加固试件的破坏形态、强度、变形能力、滞回特性和耗能能力等重要抗震性能指标。结果表明,采用预应力钢板箍加固可大幅改善高轴压比RC短柱的抗震性能;加固柱的抗震性能和变形能力随着箍板配置特征值和预应力水平的增大而增大,随轴压比的增大而减小。横向预应力钢板箍能够有效抑制斜向剪切裂缝的开展,将试件的破坏形态由剪切破坏转变成具有较好延性的弯曲破坏。该加固技术克服了以往框架柱抗震加固存在的明显缺点,可最大限度地改善加固构件的抗震性能,是一种具有广泛应用前景的抗震加固方法。

圆形钢套管加固方形混凝土柱轴心受压性能

为研究圆形钢套管加固混凝土柱的基本力学性能,进行了1根未加固的普通钢筋混凝土柱和10根圆形钢套管加固的混凝土短柱在不同加固钢套管厚度及初始轴压比下轴心受压试验,初始轴力通过对未加固试件施加后张预应力来进行模拟;在试验研究的基础上,根据应变协调原则对加固后构件轴压承载力进行了数值分析.研究结果表明,加固构件的承载力随着钢套管厚度的增加而增加,初始轴压比的变化对加固后构件的承载力影响不显著,且理论分析结果与试验结果吻合较好.

海洋结构物的重量控制

考虑到结构物的装船、吊装，对其重量和重心提出了严格的要求。以某导管架和FPSO上部组块为例，简要阐述了重量控制的流程，以及在X-steel软件环境下，就重量控制对加工设计质量和工作效率与传统做法进行了比较，有针对性的介绍X-steel软件在项目中的应用。

三种套建结构在既有房屋增层改造中的应用

为完善既有房屋套建增层改造决策系统和技术措施,结合具体工程实践,对预应力混凝土框架结构套建增层;新增结构一层顶采用内置预应力钢桁架-混凝土组合框架梁的框架结构套建增层;预应力钢-混凝土组合框架结构套建增层的设计与施工要点,进行对比分析.结果表明:预应力钢-混凝土组合框架结构套建增层,不但可实现施工过程中底层楼盖的自承重,而且与其他方案相比,结构整体造价低,施工周期短.因此,在既有房屋套建增层改造中应优先选择预应力钢-混凝土组合框架结构.

圆形钢套管加固混凝土中长柱轴压承载力研究

介绍了6根圆形钢套管加固混凝土柱轴心受压承载力的试验概况,研究在工程中常见长细比范围的该构件的力学性能。结果表明,加固构件的承载力随着长细比的增大而降低。编制了非线性分析程序用来分析构件的力学性能,理论分析结果与试验结果的对比表明,两者吻合较好。采用参数分析结果拟合的方法提出了稳定影响系数lφ计算公式,计算公式与试验结果吻合较好,并对该稳定影响系数lφ的取值进行了讨论。

导管架海洋平台基于地震作用下的多目标优化设计

把导管架海洋平台看作钢框架结构 ,并把多目标优化设计方法用于其结构的抗震设计中。以结构的总重量最小和结构的总应变能最大为优化目标 ,以导管的平均直径和壁厚作为设计变量 ,考虑强度、刚度和稳定等约束条件。并以渤海油田BZ2 8-1储油平台为例用遗传算法进行了优化设计 ,计算结果表明此方法对海洋平台的设计具有一定的参考意义。