Seismic Characteristics and Optimal Design of Ballastless Track Simply-rigid-frame Composite Girder Bridge
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摘要: 为探究高速铁路简支-刚构组合梁桥抗震优化设计方法,以我国西部地区一座跨越沟谷的高速铁路简支-刚构组合梁桥为实际工程背景,建立考虑CRTS Ⅰ型双块式无砟轨道的简支-刚构组合梁桥线桥一体化计算模型。采用反应谱法、非线性时程法及IDA法对比分析了线桥一体化模型和传统模型的抗震特性并进行优化设计。结果表明:①轨道约束改变了桥梁体系的受力行为和高、低阶振型对桥梁动力特性的影响;②对刚构桥进行抗震研究时,可选择邻近10~11跨简支梁桥作为边界条件,以消解桥跨数对刚构桥抗震性能的影响;③针对6度区地震及7度区小震、中震,刚构桥抗震研究建议不考虑轨道约束效应,而在8度、9度区中震及7度、8度、9度区大震中,轨道约束对刚构桥地震响应影响较大,进行抗震计算时建议考虑轨道约束效应;④轨道约束放大了过渡桥墩的地震响应,在过渡桥墩墩顶设置减隔震支座不仅能有效降低结构体系地震响应,同时节约其他桥跨减隔震支座的购买及施工成本;⑤轨道层间的传力及耗能部件主要是凹槽垫片和隔离层,为防止这些构件在能量传递过程中发生严重损伤,可考虑在轨道层间设置减隔震装置或植入耗能钢筋。Abstract: To explore the optimal seismic design method for simply-rigid-frame composite girder bridges in high-speed railways, this study takes a simply-rigid-frame bridge spanning a gully in western China as a case study. An integrated calculation model incorporating a CRTS Type I double-block ballastless track is developed. The response spectrum method, nonlinear time history analysis, and incremental dynamic analysis (IDA) method are used to compare the seismic characteristics of the integrated model and the traditional model, optimizing the seismic design. The key findings are as follows: ①Rail constraints alter the mechanical behavior of the bridge system, influencing both higher- and lower-order modes in the bridge’s dynamic response; ②In seismic research on rigid-frame bridges, selecting an adjacent 10- to 11-span simply supported beam bridge as the boundary condition eliminates the influence of bridge span count on seismic performance;③For seismic intensity zones of 6 degrees and small to moderate earthquakes in the 7-degree zone, rail constraints have minimal impact and can be neglected in seismic calculations. However, for moderate earthquakes in the 8-degree and 9-degree zones and large earthquakes in the 7-degree, 8-degree, and 9-degree zones, rail constraints significantly affect the seismic response of rigid-frame bridges and should be considered in seismic analysis; ④Rail constraints amplify the seismic response of transition piers. Installing seismic isolation bearings at the top of transition piers effectively reduces the structural seismic response while lowering the cost of seismic isolation supports for other bridge spans; ⑤The primary force transfer and energy dissipation components between track layers are fluted gaskets and isolation layers. To prevent severe damage during energy transfer, vibration reduction and isolation devices or energy-dissipating steel bars can be incorporated between track layers. These findings provide valuable insights for optimizing the seismic design of simply-rigid-frame composite girder bridges in high-speed railways.
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表 1 各部件刚度取值
Table 1. Stiffness values of each component
隔离摩擦层刚度/(kN·m−1) 凹槽垫片刚度/(kN·m−1) 后继结构刚度/(kN·m−1) 9.5 1.8×105 7.72×104 表 2 HRB335钢筋参数表
Table 2. HRB335 reinforcement parameters
弹性模量E0/GPa 抗拉强度$ \mathit{\text{σ}}_0 $/MPa 横截面积b/m2 直径$ {{R}}_{\text{0}} $/mm 材料常数cR1 材料常数cR2 200 455 0.01 20 0.925 0.15 表 3 混凝土参数表
Table 3. Concrete parameters
桥墩类型 $ f'_{{\mathrm{co}}} $/MPa $ f'_{{\text{cc}}}$/MPa 刚构桥墩 (C40) 35.5 41.4 简支梁桥桥墩 (C35) 30 36.5 表 4 2种模型的前10阶振型
Table 4. The first ten longitudinal natural vibration periods of two models
振型阶数 考虑轨道约束 不考虑轨道约束 自振周期/s 质量参与系数/% 振型 自振周期/s 质量参与系数/% 振型 1 1.107 0 桥梁横向正对称振动 1.362 30.84 桥梁横向正对称振动 2 0.507 72.98 桥梁纵向反对称振动 1.095 0 桥梁纵向反对称振动 3 0.486 0 桥梁纵向正对称振动 0.482 0 桥梁纵向正对称振动 4 0.441 0 桥梁横向反对称振动 0.432 0 桥梁横向反对称振动 5 0.280 0 桥梁纵向正对称振动 0.307 0 桥梁纵向正对称振动 6 0.274 0 桥梁纵向正对称振动 0.307 49.07 桥梁纵向正对称振动 7 0.254 11.76 桥梁横向正对称振动 0.305 0 桥梁横向正对称振动 8 0.241 0 桥梁横向正对称振动 0.304 0 桥梁横向正对称振动 9 0.224 0 桥梁纵向正对称振动 0.301 0 桥梁纵向正对称振动 10 0.187 0 桥梁横向正对称振动 0.302 3.3 桥梁横向正对称振动 表 5 水平设计地震基本加速度
Table 5. Basic earthquake acceleration of horizontal design
设计地震基本加速度/g 6度 7度 8度 9度 0.05 0.10 0.15 0.20 0.30 0.40 -
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