预制小箱梁UHPC-NC组合负弯矩区抗弯承载能力  

Bending-bearing capacity of UHPC-NC composite negative bending moment region of small box girder

作　　者：曹鸿猷[1] 陈云峰 李俊[2] 杨东洋 李涛 CAO Hong-you;CHEN Yun-feng;LI Jun;YANG Dong-yang;LI Tao(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan 430079,Hubei,China;China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,Hubei,China;Design Company,China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,Hubei,China)

机构地区：[1]武汉理工大学土木工程与建筑学院,湖北武汉430070 [2]中铁第四勘察设计院集团有限公司,湖北武汉430063 [3]中铁大桥局集团有限公司设计分公司,湖北武汉430050

出　　处：《长安大学学报（自然科学版）》2024年第6期59-71,共13页Journal of Chang’an University(Natural Science Edition)

基　　金：国家自然科学基金项目(51908437)。

摘　　要：先简支后连续小箱梁负弯矩区钢束施工工序繁多、效率低,施工不当导致桥面开裂等问题,无负弯矩钢束的超高性能混凝土-普通混凝土(UHPC-NC)组合负弯矩区构造能较好地解决此类问题。以3×30 m跨径小箱梁为例,建立基于混凝土塑性损伤本构(CDP)的UHPC-NC组合负弯矩区精细化有限元模型,并进行缩尺比为1∶2的模型试验。选取影响UHPC-NC组合负弯矩区受力性能的3个关键参数:UHPC厚度、UHPC层钢筋直径和UHPC抗拉强度,研究了各参数组合下负弯矩区的开裂荷载和抗弯承载力的变化规律。试验结果表明:试件的开裂弯矩为3620 kN·m,抗弯承载力为9611 kN·m,而背景桥例正常使用极限状态下最不利截面负弯矩为3300 kN·m,承载能力极限状态下最不利截面负弯矩为5838 kN·m,UHPC-NC组合负弯矩区构造的抗裂性能和承载能力均满足工程要求,且试验结果与实体有限元模型计算结果吻合良好。UHPC厚度每增加25 mm,梁体开裂荷载提高约10%,抗弯承载力提高约9%,UHPC厚度的改变对UHPC-NC组合梁体的开裂弯矩与抗弯承载力均有较为明显的影响;UHPC层钢筋直径每增大2 mm,梁体承载力提高约6%,而开裂荷载仅提升约1.8%,不同直径的UHPC层钢筋主要影响梁体开裂后的残余刚度以及抗弯承载力,对开裂荷载影响较小;而UHPC抗拉强度每增大2 MPa,梁体承载力提高约10%,但对开裂荷载影响有限,增大UHPC抗拉强度会导致试件破坏时UHPC层的残余应力增加,提高其对UHPC-NC组合梁体抗弯承载力的贡献,从而提高梁体承载力。对于30 m跨径小箱梁桥,UHPC长度建议中支点两侧各取2 m,UHPC厚度为200 mm,UHPC层钢筋直径取10 mm。The construction process of negative bending moment tendons of simply supported and then continuous small box girder beam bridge was complex and inefficient,and improper construction can lead to issues such as cracking of the bridge deck.However,the ultra-high performance concrete-normal concrete(UHPC-NC)composite negative bending moment region can effectively address these problems.A 3×30 m span small box girder beam bridge was taken as an example,a refined finite element model of the UHPC-NC composite negative bending moment region was established based on the concrete damage plasticity(CDP)constitutive model,and a 1:2 scaled model test was conducted.Three key parameters influencing the stress performance of the UHPC-NC compositenegative bending moment region were identified,UHPC thickness,UHPC layer steel bar diameter,and UHPC tensile strength.The variation in the cracking load and bending-bearing capacity of the negative bending moment region under different combinations of these parameters was studied.The results show that the cracking moment of the test specimen is3620 kN?m,the bending-bearing capacity is 9611 kN?m,while the design value of negative moment for the background bridge example under normal serviceability limit state is 3300 kN?m,and the design value of negative moment for the ultimate limit state is 5838 kN?m.The crack resistance and bending-bearing capacity of the UHPC-NC composite negative bending moment region are both in accordance with the engineering requirements,and the experimental results are well consistent with the calculation results of the solid finite element model.For every 25 mm increase in UHPC thickness,the cracking load of the beam increases by approximately 10%and the bending-bearing capacity increases by approximately 9%.The change in UHPC thickness has a significant impact on both the cracking moment and bending-bearing capacity of the UHPC-NC composite beam.For every 2 mm increase in UHPC layer steel bar diameter,the bending-bearing capacity of the beam increases by appr

关 键 词：桥梁工程 先简支后连续体系 小箱梁 负弯矩区 有限元 参数分析 

分 类 号：U448.213[建筑科学—桥梁与隧道工程]