风、浪、流荷载组合对跨海桥梁动力响应的影响

为研究跨海桥梁所受风、浪、流环境荷载及其组合影响，采用国际结构安全性联合委员会（JCSS）提出的组合模型将风浪流荷载进行组合，并考虑了风浪流要素之间的相关性，对于风浪相关性采用了耿贝尔联合概率模型，并通过风海流实现了水流与风场的联合. 以某跨海大桥为工程背景，分析了不同荷载组合对主梁动力响应的影响及其机理，并讨论了荷载组合中参与荷载时段和不同波浪场对计算结果的影响. 研究结果表明:风、浪、流荷载对主梁位移响应影响较大，以风为主要荷载的JCSS组合比以波浪和水流为主要荷载的JCSS组合跨中位移响应偏大20%～30%；随机波浪和桥梁横向基阶模态对跨中横向响应贡献显著；主梁不同位置的位移响应受同一环境要素的影响程度不同，主跨跨中响应主要受风荷载的影响，塔梁结合处主梁响应主要受波浪荷载的影响；波浪场采用规则波模拟会低估主梁跨中位移响应. 

Dynamic Response Influences of Combination Loads of Wind,Wave, and Current on Sea-Crossing Bridges

To investigate the wind, wave, and current loads and their combination influences on sea-crossing bridge, the joint committee on structural safety (JCSS) combination model was used to combine the wind, wave, and current loads considering the correlations among wind, wave, and current. The Gumbel joint probability model was adopted for the correlation of wind and wave, the combination of current and wind field was achieved by wind current. Taking a sea-crossing bridge as an engineering background, the influences and mechanism of dynamic responses on main beam were analyzed in different combinations, and the influences of secondary load period and different wave fields within load combination on calculation results were discussed. The results show that wind, wave, and current load have great influence on displacement responses of main beam, the displacement responses of the middle span of the JCSS combination with wind as the main load are larger 20%?30% than wave and current as the main load; the random wave and transverse basic mode of bridge are contribute to the lateral responses of the middle span significantly; the displacement responses at different positions of the main beam are affected by the same environmental loads differently, the responses of the middle span are mainly affected by the wind load, the main beam responses at the joint of the tower and beam are mainly affected by the wave load; the wave field simulated by regular wave will underestimate displacement responses of the middle span.