埃塞俄比亚奥莫河大跨度钢桁架桥提载加固研究
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摘要
为满足现有交通量及荷载等级的要求,需对埃塞俄比亚奥莫河上的下承式简支钢桁架桥进行提载加固。大桥全长128m,共16个节间,节间长度为8m,主桁高9m,每个主桁由2个桁架片组成,主桁中心距为9.35m。分别对体外预应力法和增设斜拉索法2种加固方案进行计算分析。计算结果显示:2种加固方案均能满足提载要求。采用体外预应力法加固后,桥梁挠度和下弦杆拉应力有较大改善,且施工简单,成本较低;采用增设斜拉索法加固后,桥梁挠度值和应力值有较大改善,全桥承载力提高比例比体外预应力法高,但对承台、地基承载力和锚固端地质条件要求较高。综合比选,确定采用体外预应力法为现阶段加固方案,增设斜拉索法为远期加固方案。
To meet the demands of current transportation volume and load grade,the simplysupported through steel truss girder bridge crossing the Omo River in Ethiopia must be strengthened to improve its load bearing capacity.The bridge is 128 min full length,consisting of 16 panels each 8mlong.The main truss is 9mhigh,and each main truss is formed of two pieces of trusses,the distance between the centers of the two trusses is 9.35 m.The two strengthening schemes were calculated,including the method of using external prestressing and the method of adding stay cables.The results of the calculation show that both schemes can meet the demands of improving the load bearing capacity of the bridge.After being strengthened by adding external prestressing,the deflection of the bridge and the tensile stresses in the lower chord are greatly rectified,the construction is simple and the cost is low.But after strengthened by adding stay cables,the deflection of the bridge and the stresses are greatly rectified,the rate of load bearing capacity improvement is higher than strengthened by adding external prestressing,but with critical demands for the ground condition of the pile cap,ground bearing capacity and the geological condition of the anchoring locations.By comprehensive comparison and selection,the external prestressing method is chosen as the strengthening scheme at present,and for further strengthening in the future,the scheme of adding stay cables will be considered.
To meet the demands of current transportation volume and load grade,the simplysupported through steel truss girder bridge crossing the Omo River in Ethiopia must be strengthened to improve its load bearing capacity.The bridge is 128 min full length,consisting of 16 panels each 8mlong.The main truss is 9mhigh,and each main truss is formed of two pieces of trusses,the distance between the centers of the two trusses is 9.35 m.The two strengthening schemes were calculated,including the method of using external prestressing and the method of adding stay cables.The results of the calculation show that both schemes can meet the demands of improving the load bearing capacity of the bridge.After being strengthened by adding external prestressing,the deflection of the bridge and the tensile stresses in the lower chord are greatly rectified,the construction is simple and the cost is low.But after strengthened by adding stay cables,the deflection of the bridge and the stresses are greatly rectified,the rate of load bearing capacity improvement is higher than strengthened by adding external prestressing,but with critical demands for the ground condition of the pile cap,ground bearing capacity and the geological condition of the anchoring locations.By comprehensive comparison and selection,the external prestressing method is chosen as the strengthening scheme at present,and for further strengthening in the future,the scheme of adding stay cables will be considered.
引文
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[2]强旭红,武念铎,姜旭,等.高强钢S460和S690火灾后力学性能试验[J].哈尔滨工业大学学报,2017,49(2):131-138.
[3]AASHTO LRFD Bridge Design Specifications[S].2007.
[4]BR-MCEB-212 Manual for Condition Evaluation of Bridges[S].AASHTO,2003.
[5]李睿,陈志强,郭峰,等.桥梁提载加固设计理论与实践[M].北京:科学出版社,2017.
[6]李满来.体外预应力加固桥梁转向块混凝土配制研究[J].世界桥梁,2018,46(4):88-91.
[7]刘明才,胡仲春,谷守法,等.波形钢腹板特大桥体外预应力设计及应用研究[J].世界桥梁,2017,45(1):45-50.
[8]王伟,张玉平,奉龙成,等.多跨矮塔斜拉桥静力荷载试验优化研究[J].世界桥梁,2017,45(1):56-61.
[9]徐佰顺,钱永久,李豹,等.大跨径曲线矮塔斜拉桥参数敏感性分析[J].世界桥梁,2016,44(5):62-67.
[10]徐刚年,王有志,王世民,等.东明黄河公路大桥主梁加固关键施工技术[J].桥梁建设,2017,47(5):88-92.
[11]芦亮,彭思谦.钢桁梁桥损伤杆件矫正施工技术[J].世界桥梁,2018,46(2):89-93.
[12]盛兴旺,郑纬奇,戴劲.考虑整体节点刚域模拟影响的钢桁梁力学效应分析[J].桥梁建设,2016,46(6):78-82.
[13]侯满,王茂强.毕都北盘江大桥钢桁梁设计关键技术[J].世界桥梁,2018,46(3):1-6.