杭州湾跨海大桥北航道桥主塔施工阶段抖振时域分析及安全性评定

杭州湾跨海大桥处在台风多发区,北航道桥为双塔斜拉桥。本文以该斜拉桥高为178.8 m的钻石形桥塔为工程背景,对主塔在施工过程中的抗风最不利阶段进行风致抖振时域分析,从而对桥塔在施工阶段中的结构安全和施工人员安全进行评定。首先选取结构在塔柱尚未合龙时和桥塔自立阶段为抗风最不利阶段,利用有限元程序对结构进行模态分析,确定了结构的动力特性和瑞利阻尼系数。然后计算在不同风偏角下的风致响应。将结构在考虑施工过程的静力结果和抖振时域分析的结果进行叠加,得到符合实际情况的结构应力和位移。结果表明,结构应力满足规范要求,不会出现裂缝;塔柱顶部抖振振幅和狄克曼指标较大,在风力较大时宜采取有效措施保证施工人员安全。

Time-Domain Buffeting Analysis and Safety Assessment on Main Pylon Construction of Cable-Stayed Bridge for North Navigational Channel of Hangzhou Bay Sea-Crossing Bridge

In this paper the time-domain buffeting response is analyzed and the safety assessment on the construction of 178.8 m-height diamond-shape pylon of a double-tower cable-stayed bridge is carried out,the bridge is the north navigational channel bridge of Hangzhou Bay Sea-Crossing Bridge located in typhoon area.Firstly,the mid-tower column to be closed and the tower standing on its own bottom are chosen as the two frailest wind-resistant stages.Then,through finite element program and modal analysis,the dynamic characteristics and parameters of Rayleigh damp of the pylon are determined.Next,the buffeting response under different wind yaw angels is calculated.Through combining the results of buffeting analysis and static analysis considering construction processes,rational stress and displacement are obtained.The results show that the stress satisfies the demand of code so that the structure would not have cracks.But the amplitude of buffeting vibration and Diekemann index are great,implying that effective measures should be taken to ensure builder's safety in dangerous weather.