某深水大跨桥梁水下振动台试验研究

A study on the underwater shaking table test of a certain deep-water long-span bridge

深水大跨桥梁若发生地震,将会造成严重的破坏;桥梁横桥向抗震研究已经取得一定进展,对纵桥向抗震研究较少。以某深水大跨桥梁结构为原型,根据弹性相似准则,以规范波、El-Centro波和汶川地震波为输入地震动,进行大比尺全桥结构纵桥向水下振动台试验,分析了桥梁加速度动力放大系数、峰值加速度、峰值应变及峰值动水压力的变化情况,研究了桥梁结构在不同地震波、不同水位、不同峰值加速度作用下的动力响应规律。结果表明:全桥结构的基频规律与单一桥墩的不同,正常水位和半水水位比无水环境下的一阶频率分别增加0.11%和0.06%,而二阶频率分别减小0.07%和0.03%;地震作用下,水的存在会影响结构的动力响应,桥梁结构的动力响应与输入的地震频谱特性和水位高低有关,动水压力在桥梁最低端最大,且动水压力影响桥梁结构的应变。

If an earthquake occurs in the area witha deep-water long-span bridge,it will cause serious damages.Some progress has been studied for the transverse direction seismic of the bridge,and there are few studies on the longitudinal direction seismic.Therefore,on the basis of a certain deep-water long-span bridge structure prototype,according to the elastic similitude law,the specification earthquake,El-Centro earthquake,and Wenchuan earthquake were used as input ground motions,deep-water long-span whole bridge structure longitudinal bridge underwater shaking table tests were carried out,to analyze the bridge acceleration dynamic amplification factor,peak acceleration,peak strain,and peak hydrodynamic pressure curves.Bridge structure dynamic responses were studied under the scenarios of different earthquakes,different water depths,and peak accelerations.Results show that the fundamental frequency of the whole bridge structure is different from a single pier.The first-order frequencies of the normal water depth and the half-water depth for without water environment increase by 0.11%and 0.06%,respectively;while the second-order frequencies decrease by 0.07%and 0.03%,respectively.When under earthquake action,the presence of water affects the bridge structure dynamic response.The bridge structure dynamic response is related to the input earthquakes frequency spectrum characteristics and the water depths.The peak hydrodynamic pressure is the largest at the bottom of the bridge,and hydrodynamic pressure affects strain of the bridge structure.