考虑双非线性影响的大跨度上承式钢拱桥地震响应研究
Earthquake Response Analysis of Long Span Steel Deck Arch Bridge Considered Effects of Elasto-plastic Finite Displacement
以研究上承式大跨度钢拱桥的非线性地震响应和损伤机理为目的,应用考虑双非线性以及地震过程中轴力变化影响的计算方法,对跨度为200m的两铰拱桥和无铰拱桥设计方案进行了计算,分析了结构在强地震荷载作用下地震响应和损伤程度,比较了计算方法、输入地震波以及结构设计条件对地震响应计算结果的影响。结果表明,上承式钢拱桥具有较好的结构抗震性能,在强地震荷载作用下损伤程度不显著;钢拱桥在地震荷载作用下无卓越的振动振型,地震响应计算需考虑多个振型的影响;当拱肋轴力达到屈服轴力的20-30%时,弹塑性地震响应计算不宜忽略轴力变化的影响。几何非线性对拱肋的弯矩地震响应有较明显的影响;柔性的两铰拱桥由于自振周期长,受到的地震荷载比对应的无铰拱略小,损伤程度也相对较轻些;无铰拱桥在拱脚截面位置容易发生地震损伤,设计时应确保拱脚截面在屈服以后不发生局部失稳。
Based on elasto-plastic large displacement analysis method considering the effects of changing axial force, this paper studied the dynamic response and damage mechanism of long span steel deck arch bridge under strong earthquake. Taking two deck arch bridge models—one is two-hinged and the other fixed—with span length of 200m as examples, the dynamic response and plastic damage under strong earthquake waves of the two bridges are calculated. The effects of different analysis procedure, earthquake wave records and design conditions on earthquake response and damage of the bridge are studied. Results show that steel deck arch bridges have preferable seismic resistant ability and occurred limited damage under strong earthquake motion; it is necessary to consider effect of more modes on earthquake response, because of nonexistent of dominant mode in response; the effect of changing axial force on the elasto-plastic response of the bridge can not be ignored when it exceeds 20-30% of yield axial force. Geometric nonlinear have remarkable effect on the moment response of arch rib. By comparing the response of two-hinged and fixed arch bridge, the two-hinged arch bridge takes smaller earthquake load than the fixed arch bridge, because the structure is more flexible and has longer natural period than the fixed bridge. In addition, fixed arch bridge is prone to damage at arch base cross-section, and it is suggested that local buckling prevent measures be taken to keep its load-carrying capability after yield.
大跨度钢拱桥 / 弹塑性地震响应 / 上承式 {{custom_keyword}} /
long span steel arch bridge / elasto-plastic earthquake response / deck bridge {{custom_keyword}} /
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