挡块对不等墩高连续梁桥横向抗震分析方法的影响

Effect of Retainer on Transverse Seismic Analytical Methods of a Continuous Girder Bridge with Different Pier Heights

根据挡块的简化滞回分析模型,针对不等墩高连续梁桥,通过IDA分析对2种典型的简化抗震分析方法(一是忽略挡块、二是横向固结)进行对比研究。结果表明:不同分析方法得到的横向剪力分布规律基本相同,墩高越大,剪力响应越小,但不同方法得到的最高墩与最矮墩的剪力可能相差数倍;不管采用哪种方法,各墩横向剪力的分布随PGA的增大都会变得更不均衡;在抗震分析时,应根据挡块强度及地震的大小选择相应的简化方法。当挡块强度较大且地震较小(PGA≤0.3 g)时,2种简化方法都不能准确反映矮墩的剪力需求及其塑性程度,此时应在分析中考虑挡块自身的力学性能。

Based on a simpl ified analytical model for the reinforced concrete side retainer, in the background of a continuous girder bridge with different pier heights, comparative research was conducted on two typical simplified seismic analytical methods （i. e. , neg-lecting the side retainer and taking the transverse connection between girder and pier to be fixed） through IDA. The results show that rising different seismic analytical methods, similar trends can be found in the distribution of transverse inertial force, which indicates that the larger the height is,the larger shear force can be expected in the pier. However, the shear force discrepancy between the tallest pier and the shortest pier can be several times different when different seismic analytical methods are adopted. Distribution of the trans-verse shear force among the piers becomes much more uneven as PGA increases regardless of the seismic analytical method applied. It is appropriate to select a reasonable simplified analytical method according to the strength of the retainer and the intensity of the earth-quake. When the strength of the retainer is large and the ground motion is relatively small （PGA^O. 8g） , the aforementioned two simplified analytical methods cannot be adopted to calculate the shear demand as well as the plastic level of the shorter piers, where the mechanical characteristics of the retainer should be taken into consideration.