基于强度和延性的钢管混凝土拱桥抗震性能评估方法

为评估并量化钢管混凝土(CFST)拱桥的抗震性能,提出了基于强度和延性的抗震性能评估方法。首先通过有限元分别计算CFST拱桥各构件(弦杆、腹杆、吊杆、横向联系、吊杆横梁和桥面纵梁)在重力代表值和小地震(0.05g)作用下的内力,然后根据各构件的破坏模式计算其极限承载力、延性比和地震作用折减系数,最后通过屈服地面运动加速度与地震作用折减系数相乘获得各构件的抗震能力A c,桥梁整体的抗震能力即为各构件最小的抗震能力A c。以大跨度中承式CFST拱桥——广西平南三桥(主跨575 m)为背景,采用该方法评估其抗震能力,将其抗震能力指标进行量化,结果表明其抗震加速度代表值为0.171g,满足Ⅶ度抗震设防目标。

Seismic Performance Evaluation Method of Concrete-Filled Steel Tubular Arch Bridge Based on Strength and Ductility

In order to evaluate and quantify the seismic performance of concrete-filled steel tubular(CFST)arch bridges,a seismic performance evaluation method based on strength and ductility is proposed.Firstly,the internal forces of CFST arch bridge components(including chords,web members,suspenders,lateral bracings,suspender cross beams and deck stringers)under the action of gravity representative value and small earthquake(0.05g)are calculated by finite element method.Secondly,the ultimate bearing capacity,ductility ratio and seismic reduction factor are calculated according to the failure mode of each component.Finally,the seismic capacity A c of each component is obtained by multiplying yield acceleration of ground motion and seismic reduction factor.The overall seismic capacity of bridge is the minimum seismic capacity A c of each component.The proposed method has been used to the Pingnan Third Bridge in Guangxi,a long-span half-through CFST arch bridge spanning 575 m.The seismic capacity of the bridge was analyzed and the seismic capacity indexes were quantified.The results show that the representative value of seismic acceleration is 0.171g,which meets theⅦ-degree seismic fortification target.