裂缝对预应力混凝土连续箱梁桥动力特性的影响
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摘要
针对箱梁较易出现裂缝的跨中底板和1/4跨腹板部位,以某四跨预应力混凝土连续箱梁为研究对象,通过ANSYS建立完整梁和裂缝梁实体有限元模型,对带有底板横裂缝和腹板斜裂缝的主梁结构进行模态分析和谐响应分析。结果表明:与完整梁相比,裂缝梁固有频率降低约0.3%;裂缝深度对结构固有频率影响最大;简谐荷载振幅和频率对腹板斜裂缝处应力强度因子影响不大,而对底板横裂缝处应力强度因子影响较大。在相同简谐荷载作用下,底板横裂缝比腹板斜裂缝危险。该研究可为同类桥梁的设计、施工和维护提供理论参考。
This paper is concerned with an investigation into span prestressed concrete continuous box girder for the cracks of the box girder mid-span floor and 1/4 span web. The study involves developing finite element models of intact beam and cracked beam using ANSYS; and thereby performing the modal analysis and harmonic response analysis of main beam with transverse cracks on the floor and oblique cracks on the web. The analysis shows that the cracked beam exhibits an approximately 0. 3% reduction in the natural frequency compared with the intact beam; the crack depth exerts a maximum effect on the natural frequency of the structure; the amplitude and frequency of harmonic load have little effect on the stress intensity factor at oblique cracks on the web,but have a great influence on the stress intensity factor at transverse cracks on the floor; and under the same harmonic load,the transverse cracks on the floor are more dangerous than the oblique cracks on the web. This study could provide a theoretical reference for the design,construction and maintenance of similar bridges.
This paper is concerned with an investigation into span prestressed concrete continuous box girder for the cracks of the box girder mid-span floor and 1/4 span web. The study involves developing finite element models of intact beam and cracked beam using ANSYS; and thereby performing the modal analysis and harmonic response analysis of main beam with transverse cracks on the floor and oblique cracks on the web. The analysis shows that the cracked beam exhibits an approximately 0. 3% reduction in the natural frequency compared with the intact beam; the crack depth exerts a maximum effect on the natural frequency of the structure; the amplitude and frequency of harmonic load have little effect on the stress intensity factor at oblique cracks on the web,but have a great influence on the stress intensity factor at transverse cracks on the floor; and under the same harmonic load,the transverse cracks on the floor are more dangerous than the oblique cracks on the web. This study could provide a theoretical reference for the design,construction and maintenance of similar bridges.
引文
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[2]詹俊华,李选栋.纵、竖向预应力筋对预应力混凝土箱梁腹板主拉应力的影响分析[J].市政技术,2016,1(34):70-72.
[3]赵文斌,刘建勋,张戎令,等.强风、干寒、大温差地区混凝土箱梁早期抗裂性分析[J].硅酸盐通报,2016,35(10):3254-3257.
[4]寇明国.某大跨PC连续箱梁桥中跨跨中附近裂缝研究[J].安徽建筑(建筑结构研究与应用),2017,3(48):122-125.
[5]张志权,邵继钢,刘建维.箱梁底板纵向裂缝对结构力学性能的影响研究[J].中外公路,2017,37(4):73-76.
[6]王海军,高帅强.工程裂缝扩展对现役混凝土结构受力性能的影响[J].黑龙江科技大学学报,2016,26(2):219-223.
[7]王瑶.裂纹损伤对大跨径预应力砼连续梁桥刚度及承载力的影响研究[D].西安:长安大学,2014.
[8]臧巨宝,李文秀,张宏.预应力连续刚构桥裂缝损伤对其承载力的影响研究[J].中外公路,2016,36(2):139-144.