T型刚构桥两种抗震设计标准对比分析研究

Comparative Analysis and Study on Two Seismic Design Standards for T-shaped Rigid Frame Bridges

摘要:

为详细对比城市T型刚构桥在抗震设计中采用《城市桥梁抗震设计规范》（CJJ 166—2011）与《公路桥梁抗震设计规范》（JTG/T 2231-01—2020）反应谱分析计算结果的差异，以2×50 m跨为例，利用MIDAS Civil建立空间动力模型，按2本规范条文分别开展抗震验算，分析其在反应谱曲线、强度、变形、抗剪及支座位移的计算差异，并探究差异成因，提出针对性设计建议。结果表明：2本规范在抗震概念、设防水准及核心计算公式上基本一致，本例按《城市桥梁抗震设计规范》算得反应谱值更大，导致E1、E2地震作用下桥墩内力和墩顶位移计算值均大于《公路桥梁抗震设计规范》；一般情况下，Ⅰ、Ⅱ类场地建议按2本规范验算并取不利值设计，Ⅲ、Ⅳ类场地按《公路桥梁抗震设计规范》计算的结果更为保守；E2地震作用下的支座验算更贴合实际抗震需求。

Abstract:

To make a detailed comparison of the differences in the response spectrum analysis and calculation results of the Code for Seismic Design of Urban Bridges (CJJ 166—2011) and the Code for Seismic Design of Highway Bridges (JTG/T 2231-01—2020) in the seismic design of urban T-shaped rigid frame bridges, taking a 2×50m bridge as an example, a spatial dynamic model is built with MIDAS Civil. The seismic verification is conducted according to the two codes. The calculation differences in response spectrum curves, strength, deformation, shear resistance and bearing displacement are analyzed, the causes are explored, and the targeted design suggestions are put forward. The results show that the two codes are basically consistent in seismic concepts, fortification levels and core formulas. In this case, the reaction spectrum values calculated according to the Code for Seismic Design of Urban Bridges are larger, resulting in the calculated values of the internal forces of the bridge piers and the displacement of the pier top under the E1 and E2 earthquakes being greater than those stipulated in the Code for Seismic Design of Highway Bridges. Under normal circumstances, for Class I and II sites, it is recommended to verify and design in accordance with the two codes and take the unfavorable values. For Class III and IV sites, the calculation results based on the Code for Seismic Design of Highway Bridges are more conservative. The bearing verification under the E2 earthquake is more in line with the actual seismic resistance requirements.