超高性能混凝土材料-窄幅钢箱组合梁极限承载力计算方法

Calculation Method of Ultimate Bearing Capacity of UHPC Composite Beam with Narrow Steel Box

为改善组合梁负弯矩区的开裂问题,提出UHPC-窄幅钢箱组合梁新结构,采用超高性能混凝土材料(UHPC)部分替换翼板中的普通混凝土(NC),对其受力性能进行研究,设计了2根不同配筋率的UHPC-窄幅钢箱组合梁以及1根NC-窄幅钢箱组合梁试件,采用反向加载的方式进行全过程静力加载试验。研究表明,随着试验梁配筋率的提高,其开裂荷载、屈服荷载以及组合梁的刚度均有明显的提升;普通混凝土组合梁翼板中NC界面之间的相对滑移相比于UHPC组合梁翼板中NC-UHPC层之间的界面滑移更加明显;翼板中采用UHPC材料可以显著地提高梁的开裂荷载,有效地改善组合梁负弯矩区的开裂问题。提出了弹性阶段弯矩以及极限承载力计算方法,与试验值吻合较好;运用ABAQUS软件对3根试验梁进行非线性模拟分析,得到模拟值与试验值基本吻合。

To improve the cracking problem in the negative bending moment zone of composite beams,a new structure of UHPC narrow steel box composite beams was proposed.Ultra high performance concrete material(UHPC)was used to partially replace ordinary concrete(NC)in the wing plate,and its mechanical performance was studied.Two UHPC narrow steel box composite beams with different reinforcement ratios and one NC narrow steel box composite beam specimen were designed,and the full process static loading test was conducted using reverse loading method.Research had shown that as the reinforcement ratio of the experimental beam increased,the cracking load,yield load,and stiffness of the composite beam all significantly increased;the relative slip between NC interfaces in the wing plate of ordinary concrete composite beams was more significant compared to the interface slip between NC UHPC layers in the wing plate of UHPC composite beams;the use of UHPC material in the wing plate could significantly increase the cracking load of the beam and effectively improve the cracking problem in the negative bending moment zone of the composite beam.A calculation method for bending moment and ultimate bearing capacity in the elastic stage was proposed,which was in good agreement with the experimental values;nonlinear simulation analysis was conducted on three experimental beams using ABAQUS software,and the simulated values were found to be in good agreement with the experimental values.In order to improve the cracking in the negative moment zone of composite beams,a new structure of UHPC-narrow-width steel box composite beams was proposed.The Normal Concrete(NC)in the wing plates was partially replaced by Ultra-High-Performance Concrete(UHPC).The mechanical properties were studied.Two UhPC-narrow-width steel box composite beams and one ordinary concrete-narrow-width steel box composite beam specimens with different reinforcement rates were designed,and the whole process of static loading test was carried out by reverse loading.The failure process,crack development,mid-span load-deflection curve and strain distribution of the specimens were analyzed.The composite beam specimens with different reinforcement ratio were analyzed.The results show that,compared with the specimens with 1%reinforcement ratio,the cracking load,yield load and stiffness of composite beams are significantly increased when the reinforcement ratio is increased to 2%.The relative slip between the NC-UHPC layer is more obvious than that between the NC-UhPC layer.The distribution of cracks in ordinary composite concrete beams is chaotic,and when the final failure occurs,the transverse main cracks are connected by thin and short oblique cracks,and the cracks are connected with each other.However,the secondary oblique cracks between the transverse main cracks of UHPC composite beams are not developed,and the distribution of cracks is more regular.Using UHPC material in the wing slab can significantly increase the cracking load of the beam and effectively improve the cracking problem in the negative moment zone of the composite beam.The calculation methods of bending moment and ultimate bearing capacity at the elastic stage are presented,which are in good agreement with the experimental values.The nonlinear simulation analysis of three test beams is carried out by Abaqus software,and the simulated values are in good agreement with the experimental values.