The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in shipbuilding.During the welding process,the nonuniform heating and rapid...The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in shipbuilding.During the welding process,the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual stresses.Owing to these imperfections,the fabricated structural members may not attain their design load,and removing these imperfections will require extra man-hours.The present work investigated controlling these imperfections at both the design and fabrication stages.A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding.A numerical simulation based on finite element modeling(FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the T-girder.The FEM results were validated with the experimental measurements of a double-sided fillet weld.Regarding the design stage,the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane distortion.Furthermore,regarding the fabrication stage,a parametric study with two variables(geometrical properties and welding sequence)was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane distortion.Increasing the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane distortion.Noncontinuous welding produced a significant reduction in the out-of-plane distortion,while an insignificant increase in the compressive residual stress occurred.展开更多
无砟轨道扣件实现了钢轨与混凝土道床、下部基础的连接。扣件受力除轮轨作用下的正常服役工作状态外,还包括桥梁地段梁端变形诱发扣件受力状态变化。为保障桥梁地段无砟轨道扣件正常服役状态,本文以32 m T型梁为载体,通过分析梁端转角...无砟轨道扣件实现了钢轨与混凝土道床、下部基础的连接。扣件受力除轮轨作用下的正常服役工作状态外,还包括桥梁地段梁端变形诱发扣件受力状态变化。为保障桥梁地段无砟轨道扣件正常服役状态,本文以32 m T型梁为载体,通过分析梁端转角、垂向位移、预留梁缝及扣件安装位置等变量,研究了T型梁梁端变形及接口构造对无砟轨道扣件受力的影响。结果表明:梁端变形引起的扣件上拔力与梁端转角、垂向位移及转角位移组合变形线性相关,提出了不同构造变量与扣件上拔力的线性表达式。研究成果可为客货共线桥梁铺设无砟轨道梁端变形控制及构造设计提供参考。展开更多
T形梁作为浮式生产储卸油装置(floating production storage and offloading unit,FPSO)船体结构的主要受力构件,是FPSO船体强度与稳定性校核过程中的关键结构。但是,常用的规范中没有明确给出FPSO船体结构中T形梁的稳定性校核方案,相...T形梁作为浮式生产储卸油装置(floating production storage and offloading unit,FPSO)船体结构的主要受力构件,是FPSO船体强度与稳定性校核过程中的关键结构。但是,常用的规范中没有明确给出FPSO船体结构中T形梁的稳定性校核方案,相关的内容被分散在其他条例中,需要工程师依据自己的经验进行选择,不利于结构设计的规范化。此外,受到T形梁两端与背面的过渡肘板和支撑结构的刚度约束影响,规范中有关计算T形梁欧拉应力有效长度的条例无法直接应用。针对这些问题,该文通过总结各个船级社的规范,归纳出一套适用于FPSO船体结构中T形梁稳定性校核方案,并结合有限元模型,利用内置监测梁方法,准确确定欧拉应力有效长度。展开更多
文摘The main configuration of ship construction consists of standard and fabricated stiffening members,such as T-sections,which are commonly used in shipbuilding.During the welding process,the nonuniform heating and rapid cooling lead to welding imperfections such as out-of-plane distortion and residual stresses.Owing to these imperfections,the fabricated structural members may not attain their design load,and removing these imperfections will require extra man-hours.The present work investigated controlling these imperfections at both the design and fabrication stages.A typical fabricated T-girder was selected to investigate the problem of these imperfections using double-sided welding.A numerical simulation based on finite element modeling(FEM) was used to investigate the effects of geometrical properties and welding sequence on the magnitude of the welding imperfections of the T-girder.The FEM results were validated with the experimental measurements of a double-sided fillet weld.Regarding the design stage,the optimum geometry of the fabricated T-girder was determined based on the minimum steel weight and out-of-plane distortion.Furthermore,regarding the fabrication stage,a parametric study with two variables(geometrical properties and welding sequence)was conducted to determine the optimum geometry and welding sequence based on the minimum welding out-of-plane distortion.Increasing the flange thickness and reducing the breadth while keeping the T-girder section modulus constant reduced the T-girder weight and out-of-plane distortion.Noncontinuous welding produced a significant reduction in the out-of-plane distortion,while an insignificant increase in the compressive residual stress occurred.
文摘无砟轨道扣件实现了钢轨与混凝土道床、下部基础的连接。扣件受力除轮轨作用下的正常服役工作状态外,还包括桥梁地段梁端变形诱发扣件受力状态变化。为保障桥梁地段无砟轨道扣件正常服役状态,本文以32 m T型梁为载体,通过分析梁端转角、垂向位移、预留梁缝及扣件安装位置等变量,研究了T型梁梁端变形及接口构造对无砟轨道扣件受力的影响。结果表明:梁端变形引起的扣件上拔力与梁端转角、垂向位移及转角位移组合变形线性相关,提出了不同构造变量与扣件上拔力的线性表达式。研究成果可为客货共线桥梁铺设无砟轨道梁端变形控制及构造设计提供参考。
文摘T形梁作为浮式生产储卸油装置(floating production storage and offloading unit,FPSO)船体结构的主要受力构件,是FPSO船体强度与稳定性校核过程中的关键结构。但是,常用的规范中没有明确给出FPSO船体结构中T形梁的稳定性校核方案,相关的内容被分散在其他条例中,需要工程师依据自己的经验进行选择,不利于结构设计的规范化。此外,受到T形梁两端与背面的过渡肘板和支撑结构的刚度约束影响,规范中有关计算T形梁欧拉应力有效长度的条例无法直接应用。针对这些问题,该文通过总结各个船级社的规范,归纳出一套适用于FPSO船体结构中T形梁稳定性校核方案,并结合有限元模型,利用内置监测梁方法,准确确定欧拉应力有效长度。
