跨海桥梁高桩承台波浪冲击荷载概率模型

PROBABILITY MODEL OF WAVE IMPACT LOAD ON THE ELEVATED PILE CAP FOR SEA-CROSSING BRIDGES

高桩承台是跨海桥梁常用的基础形式之一。但是高桩承台质量大、侧向刚度小,对波浪冲击荷载的水平分量十分敏感。在极端波浪作用下,高桩承台水平向的动力响应会明显大于静力方法算得的结构响应,严重威胁结构安全。传统波浪荷载计算方法无法充分考虑波浪冲击荷载的时变和随机特性。该文以跨海桥梁高桩承台为研究对象,开展了极端波浪冲击高桩承台尺缩模型的水槽试验。通过分析归一化后的波浪冲击荷载时程,建立了波浪冲击荷载时程模型;运用概率方法对波浪冲击荷载峰值与冲击上升段持续时间进行分析,给出了冲击荷载峰值和冲击上升段持续时间的边缘分布以及基于Copula的联合概率分布形式。

Elevated pile cap is one of the foundation types that are commonly used to support sea-crossing bridges.However,the large weight and small lateral stiffness make it sensitive to wave impact loads.The horizontal dynamic response of the elevated pile cap induced by extreme wave is obviously larger than that calculated by the static method,which will seriously threaten the safety of the structure.Moreover,traditional calculation methods of wave impact loading seldom consider the time-varying and random characteristics of wave impact loading.This paper focuses on the wave impact force on an elevated pile cap.The time history of the horizontal component of the wave impact load was obtained from the wave flume testing of the extreme wave impact on the scale model of elevated pile cap.The time history of the horizontal component of the wave impact load was obtained from the wave flume testing of the extreme wave impact on the scale model of an elevated pile cap.A wave flume test of the extreme wave impact on the scale model of an elevated pile cap is carried out.By analyzing the normalized wave impact load time history,the time history model is established.Impact maxima and rising time of the wave impact load are analyzed with probability method.The marginal distribution of impact maxima and the rising time of the wave impact load and their joint distribution form based on Copula were finally developed.