基于三维水弹性理论的箱桁组合式浮式栈桥运动响应研究

Hydroelastic response of box-truss composite floating trestle bridge based on 3-D hydroelastic theory

以一新型箱桁组合式浮式栈桥为研究对象,建立其三维有限元模型和水动力计算模型,基于三维水弹性理论对该浮式栈桥的运动响应进行数值预报。计算中考虑刚体模态和弹性模态对浮式栈桥运动响应的贡献,并将计算结果与水池试验结果和未计及桥节弹性变形的AQWA计算结果进行对比分析。采用JONSWAP谱对浮式栈桥运动响应进行短期预报,得到不同海况下浮式栈桥的运动响应。结果表明:水弹性计算结果与试验结果吻合良好,浮式栈桥整体刚度较大,弹性变形对桥节运动响应的贡献较小;在波浪圆频率小于1.0 rad/s时,水深对浮式栈桥桥节运动响应的影响较大,当波浪圆频率为0.5~1.0 rad/s时,随着水深的增大桥节垂荡响应幅值随之增大;浮式栈桥端部桥节的垂向位移响应大于中部桥节的垂向位移响应,浮式栈桥桥节横摇运动响应随着浪向角的增大而增大。

With the three-dimensional(3-D)finite element model and hydrodynamic model of a new type of box-truss composite floating trestle bridge built as the research object,the motion responses of the floating trestle bridge were predicted based on the 3-D hydroelastic theory.The contribution of the rigid body modes and the elastic modes to the motion responses of the floating trestle was considered,and the numerical results were compared with those of the model tests and the AQWA.The JONSWAP spectrum was used to predict the motion responses of the floating trestle,and the motion responses of the floating trestle under different sea conditions were obtained.The results show that:(1)the calculation results are in good agreement with the test results;(2)the overall stiffness of the floating trestle is relatively large while the contribution of elastic defor⁃mation to the motion responses of the pontoon is small;(3)the water depth has an obvious influence on the motion responses of the floating trestle bridge whenω<1.0 rad/s;(4)the heave response amplitude of the pon⁃toon increases with the increase of water depth when 0.5<ω<1.0 rad/s;(5)the heave responses of the end pon⁃toons of the floating trestle bridge are bigger than those of the middle bridge pontoons,and(6)the roll mo⁃tions of the pontoon increase with the increase of the wave direction angle.