Fracture Analysis for Torsion Problems of a Gravity Platform Column with Cracks Under Wind Load

Ocean platforms are subjected to a variety of environment loads,such as those from winds,waves,currents,etc.In this study,the torsion problems of a gravity platform column with cracks under wind load were investigated.The column was assumed to be a composite cylinder.Therefore the torsion fracture problem of a composite cylinder was considered,and new boundary integral equations for the Saint-Venant torsion problem of a composite cylinder with curvilinear cracks were derived.The problem was reduced to solving the boundary integral equations on every boundary.By using the new boundary element method,the torsion problem of the gravity platform column with a straight crack under various wind loads was calculated.The obtained results were compared with those obtained for a torsion problem of the same column without cracks to prove the applicability of the present method.The comparison showed that the detrimental effect of cracks in a column should be considered in marine engineering.

Modelling of the Vortex-Induced Motion of A Single-Column Platform with Non-Linear Mooring Stiffness Using the Coupled Wake Oscillators

A phenomenological model for predicting the vortex-induced motion (VIM) of a single-column platform with non- linear stiffness has been proposed. The VIM model is based on the couple of the Duffing-van der Pol oscillators and the motion equations with non-linear terms. The model with liner stiffness is presented for comparison and their results are compared with the experiments in order to calibrate the model. The computed results show that the predicted VIM amplitudes and periods of oscillation are in qualitative agreements with the experimental data. Compared with the results with linear stiffness, it is found that the application of non-linear stiffness causes the significant reductions in the in-line and transverse motion amplitudes. Under the non-linear stiffness constraint, the lock-in behavior is still identified at 8<Ur<15, and the trajectories of the VIM on the xy plane with eight-figure patterns are maintained. The results with different non-linear geometrically parameters show that both in-line and transverse non-linear characteristics can significantly affect the predict in-line and transverse motion amplitudes. Furthermore, the computed results for different aspect ratios indicate that the in-line and transverse motion amplitudes increase with the growth of aspect ratio, and the range of lock-in region is enlarged for the large aspect ratio.

Investigation of the Hydrodynamic Performance of a Novel Semi-Submersible Platform with Multiple Small Columns

This paper presents a novel semi-submersible(SEMI) platform concept, called the multiple small columns(MSC) SEMI that improves upon the hydrodynamic performance of the conventional SEMI. Unlike the conventional SEMI, the proposed MSC SEMI utilizes multiple small circular columns to support the deck and a large pontoon that increases the structural displacement. The novelty of the MSC SEMI is its reduction of the hydrodynamic load on the structure and suppression of its motion response, particularly in the heave direction. The MSC SEMI has the advantages of increasing the added mass, radiation damping, and natural period of the structure. A comprehensive investigation of the hydrodynamic performance of the novel MSC SEMI is conducted in both the time and frequency domains with a special focus on the resulting hydrodynamic load and motion response. Numerical simulation results demonstrate that the MSC SEMI concept can reduce the hydrodynamic load and motion response and improve the hydrodynamic performance of SEMIs as expected.

Optimum geometry of tuned liquid column-gas damper for control of offshore jacket platform vibrations under seismic excitation

In this study, the effectiveness of a tuned liquid column-gas damper, TLCGD, on the.suppression of seismic-induced vibrations of steel jacket platforms is evaluated. TLCGD is an interesting choice in the case of jacket platforms because it is possible to use the structural elements as the horizontal column of the TLCGD. The objective here is to find the optimum geometric parameters, namely orientation and configuration of vertical columns, length ratio, and area ratio of the TLCGD, considering nonlinear damping of the TLCGD and water-structure interaction between the jacket platform and sea water. The effects of different characteristics of ground motion such as PGA and frequency content on the optimum geometry are also investigated and it is observed that these features have some influence on the optimum area ratio. Finally it is observed that pulse arrangement of ground acceleration is one of the most important parameters affecting the efficiency of a TLCGD. In other words, it is found that the TLCGD＇s capability to reduce the RMS responses depends only on the frequency content of the ground acceleration, but its capability to reduce the maximum responses depends on both the frequency content and the pulse arrangement of the ground acceleration.

Torsionally Coupled Response Control of Offshore Platform Structures Using Circular Tuned Liquid Column Dampers

In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively. The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device.

基于逆有限元方法的结构变形重构研究

针对海洋平台结构健康状态难以实时监测的问题,提出一种利用应变信息重构位移场的逆有限元方法。基于Timoshenko梁和最小二乘变分理论,通过提取结构表面应变计算截面中性轴应变,推导应变场及位移场函数,并将应变信息作为逆有限元重构的输入条件,对结构变形进行回构。为提升该方法的容差性,分析了应变片位置偏差及信号噪声对精度的影响。以海洋平台立柱为试验对象,分别利用有限元分析结果及实测结构应变信息来重构位移场。试验结果表明,提出的逆有限元法在不同载荷形式下均有较高的重构精度。

提吊式液压爬模在超高劲性混凝土柱中的应用

深圳市“工业上楼”示范项目红花岭基地项目中高架平台存在超过20 m的超高劲性混凝土柱,基于传统灯笼架防护材料大量留滞、周转效率低等不足,提出采用提吊式液压爬模施工工艺。重点阐述液压爬模的应用场景、安装方式、穿插施工等方面技术要点,最终提高施工效率,节省材料资源。

Semi-Active TLCD Control of Fixed Offshore Platforms Using Artifical Neural Networks

In this paper, the control method for fixed offshore platforms using semi-active tuned liquid column damper (TLCD) is presented. The equation of motion for the platform-TLCD control system is given and the semi-active control strategy is established. A back propagation artificial neural network (ANN) is used to adjust the orifice opening of TLCD because of the nonlinear motion of liquid in TLCD. The effectiveness of the control method is verified by numerical examples.

新型立柱储油式半潜平台水动力特性频域分析

近年来,海上油气工业的远海化与超深水化对半潜平台的响应性能与储送油能力提出了新的考验。为适应更高的工作要求,我国设计生产了世界上首座具有凝析油储存和动力定位穿梭油轮外输功能的立柱储油式半潜生产平台,其运行时储油量的大幅度变化会对平台水动力特性产生影响。本文建立了考虑储油量变化的储油式半潜平台水动力模型并对其进行了频域水动力分析。结果表明:储油量越大,垂荡与横摇一阶波浪力越小,横荡一阶波浪力越大;横摇与垂荡方向的辐射效应受储油量影响大,辐射阻尼随储油量增多而减小,满载状态下最多分别减小22%与42%,附加质量变化规律类似;垂荡RAOs随储油量的增多而减小,最大差值约1 m/m,横摇RAOs在储油量6000 t时达到最大值1.45°/m;储油量变化使垂荡和横摇方向的自然频率发生偏移。

杭州泰格医药总部大楼结构设计与分析

杭州泰格医药总部大楼地上共6层,裙房3层,总高度为24.2m。主体为圆环形混凝土框架结构,内径约为28m,外径约为50m,外周长约310m。大楼主入口设置V型转换柱,主塔楼顶部设置大悬挑观景平台,悬挑长度约为12m。整体结构存在扭转不规则、楼板不连续、尺寸突变、竖向构件间断和穿层柱等多项不规则项。本工程通过盈建科YJK和PKPM等计算软件对整体结构进行建模分析,分别研究其在小震、中震、大震作用下的抗震性能,并运用MIDAS Gen等有限元软件分别对裙房楼板的温度应力、屋顶大悬挑观景平台的舒适度和V型转换柱关键节点的应力进行了专项分析。分析结果表明:整体结构各项计算指标均能满足相关规范要求,在地震作用下仍具有较好的承载力和延性;本工程结构抗震性能良好,能够满足预定的抗震性能目标,结构安全可靠。

桥式车站装配式钢结构雨棚设计与施工要点简析

针对现有铁路客站钢结构站台雨棚结构形式和施工技术存在的问题,提出一种全新的装配式站台雨棚结构。通过对桥式车站装配式钢结构雨棚设计与施工要点分析,提出了关键节点细部构造做法,给出了施工关键要点质量控制措施,在保证结构安全的同时,大大提高施工速度和质量,改善雨棚的观感质量,对推动铁路站台有柱雨棚装配式标准化建设具有积极的意义。

兼具发电功能的张力腿平台系统动力响应研究

本文针对一种由张力腿平台-内嵌式波能发电装置组成的多功能张力腿平台系统,考虑平台本体有限位移、六自由度运动耦合以及气室空气压缩性等非线性因素,建立系统的耦合动力学方程。采用变步长四阶-五阶龙哥库塔算法编写了数值仿真程序,计算得到了包括平台本体六个自由度运动、四个U型振荡液柱液面变化和八个气室-涡轮组的气室压力的响应。通过文献对比,验证了水动力模型和计算程序的正确性。计算结果表明:工作海况中振荡液柱液面变化能有效引起气室振荡;张力腿平台系统的动力响应满足油气生产作业要求。不同节流孔板开孔率、不同气室高度敏感性分析表明系统的运动性能稳定。建议发电系统开启时保持节流孔板完全打开和较小的气室高度。

多跨连续现浇简支箱梁施工中模板滑动体系应用技术研究

镇江关站1号五线特大桥A32^(#)-A39^(#)墩墩身高度5.3~24 m,站台梁采用支架法施工,模板采用工厂加工的定型钢模板。站台梁单孔长32.64 m,梁高1.8 m,底板宽3.4 m,顶板宽6 m。文中通过对模板工程进行优化,分析了滑动模板体系在多跨连续现浇梁施工中的滑动体系设计、施工技术和经济效益。

水中墩钢板桩围堰施工技术研究

沿海地区由于独特的地理、地质条件,分布着较多的河流,河道表层分布淤泥,其下孤石非常发育,地质条件复杂,加之孤石自上而下分布,分布面较广,加大了桥梁的施工难度。以国道G240线台山大江至那金段改扩建工程锦石大桥水中墩承台墩柱施工为对象,采用钢板桩围堰的施工方法,介绍施工过程中遇到的问题和解决措施。

高层框架结构临边构造柱施工用悬挑操作平台设计

在高层框架结构建筑中,通常采用幕墙维护体系和附着式升降脚手架,大多存在砌体墙和临边构造柱等,一旦爬架提升前因为各种原因未能及时施工时,上述临边构造柱的施工因没有外防护将增大施工的安全风险。结合工程实例,介绍了一种可周转、组装式临边定型悬挑操作平台的设计方案,阐述了其设计要点、构造措施。实践证明,该设计方案有效解决临边构造柱施工、施工工期、施工成本等多重问题,而且还能保证施工安全及工程质量。

逆作桩柱一体安装加设回转钻机平台混凝土底座施工技术研究

逆作桩柱一体安装施工技术在不同结构工程中应用广泛,为控制好钢管柱垂直度,解决逆作桩柱一体安装施工过程中钢管柱环板与回转钻机平台夹持作用位置点冲突问题,以克服钢管柱插入桩内混凝土时产生的浮力阻碍。该文结合北京城市副中心站综合交通枢纽工程,重点介绍桩柱一体安装施工工艺、回转钻机平台混凝土底座的原理及作用。应用该技术解决桩柱一体安装施工的难题,为同类工程施工提供参考。

地铁车站站台柱抗爆性能及其优化设计

地铁车站的整体抗爆安全性能与其站台柱抗爆能力的大小密切相关.为此,从截面选择、轴压比的确定、箍筋形式及配筋率等方面对站台柱的抗爆性能进行了系统研究,并提出优化设计方法.研究结果表明:在对地铁车站站台柱进行抗爆设计时,截面形状宜采用圆形;增大箍筋直径或提高纵筋配筋率都不能显著提高钢筋混凝土柱抗爆性能,减小箍筋间距对提高柱子的抗爆能力具有明显的效果;针对圆柱提出改善其抗爆性能的箍筋配置方法;提出了站台柱合理安全防护距离的概念,并针对典型地铁车站给出建议值.

基于全生命周期管理的六氟化硫物料核算技术研究

为了更有效地管理逐渐增多的含六氟化硫电气装置,设计了一种改进型的六氟化硫制备与纯化装置,可有效地去除六氟化硫当中的杂质,并建立物料核算公式。在六氟化硫的运输与使用阶段,改进了RFID射频识别技术,分别在电子标枪上加装微传感器和在读写器上加装浓度检测器,实现六氟化硫的物料跟踪;将上述阶段的物料数据上传至数据平台,以便完成对六氟化硫物料的全生命周期管理。经过试验验证,该技术不仅满足不同类型的电力装置计算,还可满足同一装置不同时期的物料核算,提高了六氟化硫的全生命周期管理能力。

圆筒形超深海半潜式钻井储油平台运动特性分析

使用Pro/E软件对SEVAN 650平台和GVA 7500平台建模,将模型导入ANSYS Workbench程序的Hydrodynamic Diffraction模块,计算出2座半潜式钻井平台南海海况风暴自存状态下的运动响应幅值算子,得出2座平台各自的垂荡、横摇和纵摇特性曲线,进而对2座平台南海海况风暴自存状态下的运动特性进行对比分析.结果表明:SEVAN 650圆筒形半潜式平台在原油存储性能和甲板承受可变载荷性能优于GVA 7500平台的前提条件下,其在风暴自存状态时具有比GVA 7500更优的抗倾性能,但SEVAN 650平台在风暴情况下的垂荡响应幅值需要进一步减小.

海洋平台——摇摆柱减振体系中连接杆优化研究

摇摆结构体系是最近几年发展起来的新型结构,研究表明摇摆柱施加于海洋平台上可有效降低平台的动力反应。基于摇摆柱体系的新型海洋平台结构形式,以JZ20-2北高点井口平台为例,利用ANSYS有限元软件对该结构体系进行了地震作用和冰力荷载下的数值仿真分析,计算了摇摆柱与海洋平台之间的连接杆在不同刚度、不同数量时的平台结构位移和加速度反应。分析结果表明,连接杆的刚度和数量对海洋平台结构的位移和加速度反应有较大影响,当其达到某一值或在特定范围内时,对海洋平台振动的控制效果最为明显,为海洋平台——摇摆结构体系的实际应用提供了理论依据。