A STUDY FOR WAVE RESPONSE OF HORIZONTAL-ARCH BRIDGES WITH SEMI-SUBMERSIBLE FLOATING FOUNDATIONS

本研究以半潜式浮式基础取代浮箱基础的“半潜式浮式基础横拱桥”为研究对象。本研究针对浮式基础的波浪响应特性，探讨基础形状对浮式基础抗波设计的影响，并利用轴对称有限元程序计算了各浮式基础的绕射力和辐射力。程序采用无限单元满足无穷远辐射条件。桥梁结构采用弹性梁模型，并利用NASTRAN通用有限元程序对整个结构体系进行了分析。应用该程序成功地分析了流体弹性结构体系，并在基础下沉位移为常数的条件下，考察了浮体基础的影响。数值算例表明，半潜式浮桥具有较好的特性。此外，大坂市政府办公室正在计划在舞岛Yumeshima通道浮桥研究，并在时域瞬态响应分析，考虑非线性的挡泥板和桥梁系统的弹性变形。

This research has studied "Horizontal-arch bridges with semi-submersible floating foundations, " which the floating pontoon foundations are replaced by the semi-submersible floating foundations. In this study, the attention has been paid on the wave response characteristics, and the effect of the foundation shapes are examined to improve the wave-resistant design.The diffraction and radiation wave forces have been calculated by using axi-symmetric Finite Element Program for each floating foundation. The program enploys infinite elements for satisfying radiation condition at infinity. The bridge structure is modeled as a elastic beam, and the whole structural system has been analyzed by NASTRAN,general purpose F.E.M.program. The fluid-elastic structure system has successfully been analyzed by the procedure.The effect of the floating foundations have been examined on the condition that the immersed displacement of the foundation has the constant value. Numerical examples have shown that the semi-submersible type floating bridge has an improved characteristics. Moreover, the floating bridge that the Osaka municipal office is now planning at Maishima-Yumeshima channel is studied, and the transient response analysis in the time-domain considering nonlinearity of the fender and the elastic deformation of the bridge system has also been made.