Investigation of spatially varying ground motions and soil-structure interaction effect on bridge girder pounding

研究了地震动空间变化和土-结构相互作用对桥梁结构相对响应的影响。该研究项目为期三年，2005财政年度是最后一年，调查结果总结如下：如果土壤较软，且相邻结构的细长度不相同，即使它们具有相同的固定基础基频并经历相同的地面激励，也可能发生碰撞，当频率比大于0.6时，考虑了非均匀地震动和土-结构耦合作用的影响。由于较大的接触力，结构相互作用可显著地放大主梁损坏的可能性。在频率比为1.0左右的范围内，以及在较高的频率范围内， ...更多信息 NCY比大于1.6的非均匀地震动比土-结构相互作用的影响更大。然而，如果相邻结构具有不同的细长度，即使在频率比为1.0的情况下，土-结构相互作用的影响也可能比非均匀地震动的影响更大。尽管日本设计规范是目前最先进和最严格的规范，并且隐含了地震动空间变化的影响，但所要求的座位长度可能仍然不够，特别是当相邻桥梁结构是柔性的并且两个结构经历不同的SSI时。如果支撑土壤在空间上不均匀，即使两个相邻结构具有相同的伸长、相同的基频并且经历相同的地面激励，也可能发生不同的土壤-结构相互作用。这种不均匀的土-结构相互作用会显著影响相对结构响应。在今后的设计规范中，应将其与空间非均匀地面激励的影响一并考虑。少

The subject of the investigation is the simultaneous influence of spatial variation of ground motions and soil-structure interaction on the relative response of bridge structures. The duration of this research project is three years, and the fiscal year 2005 is the last year.In the following the results of the investigation are summarized :If the soil is soft and the neighbouring structures do not have the same slenderness, even though they have the same fixed-base fundamental frequency and experience the same ground excitation, pounding can take place, because with different slenderness both adjacent structures can vibrate out-of-phase.In the case of frequency ratio larger than 0.6 the simultaneous effect of non-uniform ground motions and soil-structure interaction can significantly amplify the girder damage potential due to larger contact forces. Consequently, damage due to multiple subsequent poundings is possible.In the frequency ratio range around 1.0 and also in the higher freque … More ncy ratio range above 1.6 non-uniform ground motions have stronger influence than soil-structure interaction. If the adjacent structures have different slenderness, however, soil-structure interaction can have stronger effect than non-uniform ground motions even at the frequency ratio of 1.0.Although the Japanese design specification is currently the most advanced and strictest regulation and implicitly includes the effect of spatial variation of ground motions, the required seating length may still not be adequate, especially when the neighbouring bridge structure is flexible and when both structures experience different SSI.Different soil-structure interaction can also occur, even though both adjacent structures have the same slenderness, the same fundamental frequency and experience the same ground excitation, if the supporting soil is spatially not uniform. This unequal soil-structure interaction can significantly affect the relative structural response. It should be incorporated together with the influence of spatially non-uniform ground excitation in future design regulations. Less