地震动作用对桥上钢轨伸缩调节器的影响分析

Impact of Seismic Effects on Rail Expansion Joints on Bridge

钢轨伸缩调节器(Rail Expansion Joints,REJ)是缓解大跨桥上无缝线路梁轨相互作用的主要轨道部件。为确定不同地震区REJ的伸缩预留量,以某客运专线48m+3×80m+48m连续梁桥为例,建立考虑地震作用下桥梁与轨道结构相互作用的REJ-桥-墩一体化计算模型,分析了地震波频谱特性、行波效应、活动支座摩擦系数、REJ布置方式与位置及地震波加速度幅值等对REJ伸缩量的影响。研究结果表明:地震对REJ伸缩量的影响较大,建议确定REJ伸缩预留量时考虑地震影响,并按照多遇地震设防考虑相应的增加值;REJ的伸缩量也受到地震频谱特性的影响,波频范围越宽、幅值越大伸缩量也越大;地震作用下REJ最大伸缩量随地震传播速度、活动支座摩擦系数的降低以及地震波加速度幅值的增加而显著增大,其中波速影响较为显著;REJ铺设位置也对其在地震作用下的伸缩量有较大影响,建议在满足受力等要求前提下尽可能将REJ铺设在距梁缝较远位置;确定了第Ⅰ、Ⅱ类场地对应不同抗震设防烈度由地震引起REJ伸缩预留量建议增加值,其中第Ⅱ类场地对应伸缩预留量建议增加值约为第Ⅰ类场地的2倍。

The rail expansion joints（REJ） is an essential track component for relieving the interaction between bridge and CWR track on large-span bridge. In order to ascertain the expansion capacity of REJ in different seismic zones, based on the case study of a continuous beam bridge with span of 4B m＋3 × 80 m＋ 4B m in a certain passenger dedicated line, this paper established an REJ-bridge-piers calculation model considering the bridge-track interaction principle under the action of earthquake, and analyzed the influence of seismic wave spectral characteristics, the traveling wave effect, the friction coefficient of movable support, the REJ arrange- ment and location and the acceleration amplitude of seismic wave on the expansion amount of REJ. The results showed that the effect of earthquake on the expansion amount of REJ is considerable. The earthquake effect should be considered during the determination of the expansion capacity of REJ and the additional expansion a- mount of REJ should be considered to guard against low-level earthquakes. The expansion amount of REJ was influenced by the seismic wave spectral characteristics. the wave amplitude, the bigger the expansion amount The wider the wave frequency range and the stronger of REJ was. Under the action of earthquake, with the decrease of propagation velocity of earthquake, friction coefficient of movable support, and the increase of ac- celeration amplitude of seismic wave, the maximum value of expansion amount of REJ increased significantly, while the impact of seismic wave velocity was significant. The laying position of REJ also posed a great impact on the expansion amount of REJ in earthquake. The REJ should be laid as far as possible from the beam seam on condition that force requirement and other requirements are all satisfied. The recommended values of the ad- ditional expansion capacity of REJ under different seismic fortification intensity levels for Class I and Class II sites were all ascertained respectively. The recommended values for Class Ⅱ site are about twice of Class I site under the same seismic fortifieation intensity.