系梁对哑铃型高桩承台基础抗震性能影响

Influence of tie-beam on seismic response of a dumbbell shaped elevated pile cap foundation

针对我国大跨度桥梁目前常用的哑铃型高桩承台基础,分析了系梁对其地震反应的影响因素,采用反应谱分析方法重点讨论了在工程可行的几何尺寸范围内,系梁轴向刚度和抗弯刚度对哑铃型高桩承台基础的地震反应影响规律,进一步讨论了系梁底桩基对系梁刚度的影响。结果表明:设置系梁后,系梁轴向刚度和抗弯刚度会对哑铃型高桩承台基础的地震反应产生较大影响,但在工程可行几何尺寸范围内,系梁轴向刚度的变化对其影响不大,而抗弯刚度的变化对其影响较大,且抗弯刚度越大对基础抗震越有利。在系梁底布置桩基可有效提高系梁的刚度。

The influence of tie-beam on seismic response of a dumbbell shaped elevated pile-cap foundation was analyzed, this type foundation was used widely in long span bridges in China at present. The effects of tie-beam＇s stiffness were .selectively analyzed using the response spectrum method within the geometric size range of engineering feasibility. Furthermore, the effect of the pile assembled below a tie-beam on the tie-beam＇s stiffness was discussed. The results showed that the seismic response of the foundation is influenced greatly by the tie-beam＇s axial stiffness and bending stiffness after a tie-beam is built; but it is affected little by the tie-beam＇s axial stiffness and largely by the tie-beam＇s bending stiffness within the geometric size range of engineering feasibility; the tie-beam＇s bending stiffness is improved with a pile placed below it.