卸载程度对钢桁梁桥主桁构件加固效果的影响
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摘要
早期修建的部分钢桁梁桥已无法满足当前通行能力的要求,需要对原桥主桁进行加固。桥梁加固通常是在负载情况下进行,需要考虑加固构件的分阶段受力,不同的加固施工方案所对应的卸载程度会产生不同的加固效果。该文结合松浦大桥扩宽加固工程,利用ANSYS单元生死技术模拟加固施工过程,提出了能够考虑加固板件应变滞后的有限元模拟方法。分别计算新旧构件在三种不同卸载程度的加固方案下的应力分布,从构件安全度及材料利用率两方面分析卸载程度对加固效果的影响。最后综合考虑社会影响比选施工方案。结果表明:所提出的构件加固模拟方法能有效考虑应变滞后效应并实现杆件的加固模拟;加固构件安全度和加固材料利用率随着卸载程度的增加而提高;综合社会经济性影响,推荐采用先更换下层桥面,再拆除上层桥面,然后加固主桁结构,最后安装新的上层桥面的施工方案。
Some early-built steel truss bridges can no longer meet the requirements of current traffic capacity, so it is necessary to reinforce the main trusses of the original bridges. Bridge reinforcement is usually carried out under load. It is necessary to consider the phased forces of the reinforcement members. The different degrees of unloading corresponding to different reinforcement construction schemes will produce different reinforcement effects. In this paper, based on the reinforcement and reconstruction project of the Songpu Bridge, the element birth and death technology of ANSYS is used to simulate the strengthening construction process. A finite element simulation method considering the strain lag of the reinforced plates is proposed. The stress distributions of the old and new members under three different reinforcement schemes corresponding to different degrees of unloading are calculated. The influence of unloading degrees on the reinforcement effect is analyzed in terms of component safety and material utilization efficiency. The comparison and selection of construction schemes are carried out considering the social impact. The results demonstrate that the proposed component reinforcement simulation method can effectively consider the strain lag effect and is convenient to simulate the reinforcement of truss members. Safety degrees of reinforced members and utilization ratios of reinforced materials increase with the increase of the unloading degree. Considering the social impact, it is recommended to adopt the construction scheme which replaces the lower deck first, removes the upper deck, then reinforces the main truss structure and finally installs a new upper deck.
Some early-built steel truss bridges can no longer meet the requirements of current traffic capacity, so it is necessary to reinforce the main trusses of the original bridges. Bridge reinforcement is usually carried out under load. It is necessary to consider the phased forces of the reinforcement members. The different degrees of unloading corresponding to different reinforcement construction schemes will produce different reinforcement effects. In this paper, based on the reinforcement and reconstruction project of the Songpu Bridge, the element birth and death technology of ANSYS is used to simulate the strengthening construction process. A finite element simulation method considering the strain lag of the reinforced plates is proposed. The stress distributions of the old and new members under three different reinforcement schemes corresponding to different degrees of unloading are calculated. The influence of unloading degrees on the reinforcement effect is analyzed in terms of component safety and material utilization efficiency. The comparison and selection of construction schemes are carried out considering the social impact. The results demonstrate that the proposed component reinforcement simulation method can effectively consider the strain lag effect and is convenient to simulate the reinforcement of truss members. Safety degrees of reinforced members and utilization ratios of reinforced materials increase with the increase of the unloading degree. Considering the social impact, it is recommended to adopt the construction scheme which replaces the lower deck first, removes the upper deck, then reinforces the main truss structure and finally installs a new upper deck.
引文
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[2]张春雷.浙江路桥鱼腹式铆接钢桁梁大修设计[J].城市道桥与防洪,2017,1(1):86―89.Zhang Chunlei.Overhaul design of fish-belly riveted steel truss girder in Zhejiang Road[J].Urban Roads Bridges&Flood Control,2017,1(1):86―89.(in Chinese)
[3]王元清,宗亮,施刚,等.加固新技术及其应用研究[J].工业建筑,2017,47(2):1―6,22.Wang Yuanqing,Zong Liang,Shi Gang,et al.Application research on new strengthening technologies for steel structures[J].Industrial Construction,2017,47(2):1―6,22.(in Chinese)
[4]吕宏奎,周彦.某全焊钢桁架连续梁桥加固方案研究[J].铁道工程学报,2014,31(5):63―67.LüHongkui,Zhou Yan.Research on the reinforcement of a continuous all-welded steel truss bridge[J].Journal of Railway Engineering Society,2014,31(5):63―67.(in Chinese)
[5]苏庆田,张其林,但泽义,等.宝钢二号高炉炉体框架的加固设计[J].建筑结构学报,2003,24(5):31―35.Su Qingtian,Zhang Qilin,Dan Zeyi,et al.Strengthening design of frame of Baosteel No.2 blast furnace[J].Journal of Building Structures,2003,24(5):31―35.(in Chinese)
[6]Vild M,Bajer M.Strengthening under load:The effect of preload magnitude[J].Procedia Engineering,2016,(161):343―348.
[7]董文斌.卸载与不卸载粘钢加固砼构件承载能力研究[D].武汉:华中科技大学,2003.Dong Wenbin.Study on load-bearing capacity of reinforced concrete members reinforced with steel plates unloaded and non-unloaded[D].Wuhan:Huazhong University of Science and Technology,2003.(in Chinese)
[8]丁亚红,王兴国,曾宪桃,等.持续荷载作用下外贴FRP片材加固混凝土梁承载力影响因素分析[J].工程力学,2007,24(增刊1):154―158.Ding Yahong,Wang Xingguo,Zeng Xiantao,et al.Preloading effect on load-capacity of RC beams strengthened with FRP laminate[J].Engineering Mechanics,2007,24(Suppl 1):154―158.(in Chinese)
[9]JTG/T J22―2008,公路桥梁加固设计规范[S].北京:人民交通出版社,2008.JTG/T J22―2008,Specifications for strengthening of highway bridges[S].Beijing:People’s Transportation Press,2008.(in Chinese)
[10]JTG/T J23―2008,公路桥梁加固施工技术规范[S].北京:人民交通出版社,2008.JTG/T J23―2008,Technical specifications for strengthening construction of highway bridges[S].Beijing:People’s Transportation Press,2008.(in Chinese)
[11]YB 9257―96,钢结构检测评定及加固技术规程[S].北京:冶金工业出版社,1997.YB 9257―96,Technical Specification for inspection,assessment and strengthening of steel stuctures[S].Beijing:Metallurgical Industry Press,1997.(in Chinese)
[12]祝瑞祥,王元清,戴国欣,等.负载下钢结构构件增大截面加固设计方法对比分析[J].四川建筑科学研究,2014,40(1):98―103.Zhu Ruixiang,Wang Yuanqing,Dai Guoxin,et al.Comparative study on design methods for steel structural members strengthened by increasing the section area while under load in different codes[J].Sichuan Building Science,2014,40(1):98―103.(in Chinese)