UHPC免模板湿接缝抗弯性能试验  

Experiment on flexural behavior of UHPC wet joints without formwork

作　　者：李凌霄 邹德强 王嘉兴 黄心仪 李立峰[1] LI Ling-xiao;ZOU De-qiang;WANG Jia-xing;HUANG Xin-yi;LI Li-feng(College of Civil Engineering,Hunan University,Changsha 410082,Hunan,China;China Construction Fifth Engineering Bureau Co.,Ltd.,Changsha 410004,Hunan,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]中国建筑第五工程局有限公司,湖南长沙410004

出　　处：《长安大学学报（自然科学版）》2024年第6期81-91,共11页Journal of Chang’an University(Natural Science Edition)

基　　金：国家自然科学基金项目(51978257,52278176);中建五局科技研发计划项目(cscec5b-2020-17)。

摘　　要：针对预制钢-混组合结构桥面板湿接缝处的受力特点和现有接缝构造形式,提出一种带预制超高性能混凝土(UHPC)薄板的免模板湿接缝构造形式。为了检验这种结构的力学性能,设计了5片试验梁,包括2根整体梁、1根支模接缝梁和2根免模板接缝梁,以钢纤维掺量为试验参数,采用四点加载的方式,完成了试验梁抗弯性能试验,获得了试验梁的开裂荷载、裂缝分布、破坏模式和应力-应变状态等关键试验结果。试验结果表明:接缝梁与整体梁均发生弯曲破坏,各接缝梁的破坏模式基本相同,均为首先在UHPC-NC界面上出现裂缝,随着荷载的增加,原有裂缝宽度增加、新裂缝相继出现,达到破坏极限状态时主裂缝贯通、钢筋受拉屈服、顶板压溃,其中,需支模接缝梁的主裂缝集中在普通混凝土(NC)预制段,免模板接缝梁的主裂缝集中在新旧混凝土交界面及其临近接缝区域;与NC整体梁相比,带预制UHPC薄板的免模板接缝梁抗弯承载力略有降低、但抗裂性能明显增强;钢纤维掺量的提高可以增强UHPC-NC界面黏结,提升试件的抗裂性能和抗弯承载力,钢纤维掺量(质量分数,下同)为1.0%的含预制UHPC薄板的免模板接缝梁抗弯承载力仅微弱降低,而其抗裂性能仅次于UHPC整体梁。该方法解决了预制结构接缝位置易开裂的问题,且大大简化了施工,可用于实际工程,同时推荐UHPC的钢纤维掺量为1.0%左右。According to the mechanical characteristics of wet joints of prefabricated steel-concrete structural deck slabs and the existing joint construction forms,a ultra high performance concrete(UHPC)wet joint without formwork was proposed.In order to test the mechanical behavior of this structure,five test beams were designed,including two overall beams,one joint beam with formwork and two joint beams without formwork,and the steel fiber content was used as the test parameter.The flexural behavior of the test beams was investigated by four-point loading,and the specimen's cracking load,crack distribution,damage mode and stress-strain state and other key test results were obtained.The results show that both the joint beams and the overall beams undergo bending failure,and the failure modes of each joint beams are basically the same.All of joint beams show cracks appeared in the UHPC-NC interface first.The width of the old cracks increases and the new ones appeare one after another with the load increase.When reaching the limit state,the main cracks penetrat through the webs,the reinforcement yield in tension,and the top plate collaps.The main cracks of the joint beams with formwork are concentrated in the normal concrete(NC)prefabricated section,while the main cracks of the joint beams without formwork are concentrated in the interface between old and new concrete and its adjacent joint area.Compared with the NC overall beam,the joint beams of the formwork free with prefabricated UHPC thin plates have reduced bending bearing capacity and enhanced crack resistance.The increase of the steel fiber content can enhance the bonding of UHPC-NC interface,and improve the cracking resistance and the bending bearing capacity of the specimens.The bending bearing capacity of the formwork free joint beam containing prefabricated UHPC thin plate with a steel fiber content of 1.0%is only slightly reduced,and its crack resistance is only second to that of UHPC overall beam,solving the problem of easy cracking of UHPC-NC interface,indica

关 键 词：桥梁工程 预制桥面板 试验研究 UHPC湿接缝 抗裂性能 抗弯承载力 

分 类 号：U443.32[建筑科学—桥梁与隧道工程]