RPC混凝土在简支变连续桥梁中的应用研究  

Research on the Application of Reactive Powder Concrete on Bridge Transforming from Simply-supported into Continuous Girders

作　　者：李军昌 LI Junchang(China Railway 21st Bureau Group Co.Ltd.,Lanzhou Gansu 730070,China)

机构地区：[1]中铁二十一局集团有限公司,甘肃兰州730030

出　　处：《铁道建筑技术》2020年第8期98-102,共5页Railway Construction Technology

基　　金：中国铁建股份有限公司科技重大专项计划项目(2019-A01-4)。

摘　　要：本文以5×70m先简支后连续箱梁桥为工程背景,从理论方面对通过引入活性粉末混凝土(RPC),利用其高强度、高韧性的特点不再设置负弯矩钢束从而简化施工流程并避免负弯矩段箱梁混凝土开裂的应用效果进行研究。研究结果表明,去除负弯矩钢束后,结构抗裂检算结果不能满足规范要求,荷载长期/短期效应组合下正截面最大拉应力分别为1.35 MPa/3.83 MPa,斜截面最大拉应力为3.91 MPa;将墩顶现浇段更换为RPC100混凝土后,通过局部分析,现浇段主拉应力最大值为6.53 MPa,预制梁段主拉应力大于0.7ftk=1.92 MPa的范围为墩顶支座左右两侧各3.5m,为保证结构安全,应考虑将此范围内的混凝土均采用RPC混凝土替代。The reactive powder concrete(RPC)has high performance in strength and toughness,by the application of RPC,the setting of prestressed steel bundle in upper plate and the cracking of roof in the negative bending moment can be avoided,also the construction process can be simplified.As taking a 5×70 m bridge transforming from simply-supported into continuous girders for an engineering background,the results showed that after the removing of prestressed steel bundle in upper plate,the section crack resistance can not comforts the code requirements,the maximum tensile stress of normal section under the combination for long-term/short-term action effects is 1.35 MPa/3.83 MPa respectively,and the maximum principal tensile stress of oblique section is 3.91 MPa.By replacing the concrete of cast-in-place segment on pier top with RPC100,the maximum principal tensile stress in cast-in-situ segment is 6.53 MPa through the results of local analysis,and the distribution range in precast segment which the principal tensile stress is greater than 0.7 ftk=1.92 MPa is between 3.5 m both left and right sides of the bearings on the top of pier.To ensure the security of structure,the concrete in this range should be replaced by RPC100 concrete.

关 键 词：简支变连续 顶板预应力钢束 RPC混凝土 顶板开裂 主拉应力 数值分析 

分 类 号：U448.21[建筑科学—桥梁与隧道工程] U441.5[交通运输工程—道路与铁道工程]