钢-混凝土-ECC组合梁受弯性能试验研究与有限元分析

Experimental research and FEA on bearing capacity under negative moment of steel-concrete-ECC composite beams

为解决连续组合梁桥负弯矩区桥面板易于开裂的问题,提出了适用于连续组合梁桥负弯矩区的钢-混凝土-ECC组合桥面结构,将表面一定厚度的混凝土替换为混杂纤维ECC,提高连续组合梁桥负弯矩区耐久性。设计并完成了2根钢-混凝土-ECC组合梁和1根钢-混凝土组合梁的静力单调加载试验。结果表明:在纵向配筋相同的情况下,ECC组合桥面结构的屈服荷载和极限荷载高于传统组合结构的,开裂荷载远高于传统组合结构的,且裂缝数量减少、宽度减小。基于试验数据,对GB 50017—2017《钢结构设计标准》中组合梁负弯矩受弯承载力计算方法进行了修正并验证,计算值与试验值吻合良好。利用ABAQUS软件建立了钢-混凝土-ECC组合桥面结构有限元模型,进行试验模拟和参数分析,研究发现ECC厚度增加对各项指标提升效率呈下降趋势;配筋率与各项指标成正比;在短期荷载作用下,2层配筋的组合梁开裂荷载与3层配筋的组合梁接近,但屈服荷载和极限荷载有明显提高。

In order to solve the problem that it is hard to control the cracking of the slabs under negative bending moments,a novel type of steel-concrete-ECC composite bridge structure was proposed for the negative-moment area of continuous composite beam bridges.Replacing the concrete on the surface with a certain thickness with hybrid fiber ECC can improve the durability of the continuous composite beam bridge in the negative-moment area.The static monotonic loading test of two steel-concrete-ECC composite beams and one steel-concrete composite beam was designed and completed.The study shows that with the same longitudinal reinforcement,the yield and ultimate load of the composite bridge structure with ECC are higher than that of the traditional composite structures,the cracking load is much higher,and the number and width of cracks are also reduced.Based on tests,the calculation method of the negative-moment bearing capacity of the composite beam in GB 50017—2017‘Standard for design of steel structures’was modified and verified,and the results were in good agreement with the tests.The ABAQUS software was employed to establish finite element(FE)models of the steel-concrete-ECC composite bridge structure and the experimental simulation and parametric analysis were carried out.It is indicated that as the thickness of ECC increases,the improvement efficiency of each index decreases.The reinforcement ratio is proportional to each index.Under the short-term load,the cracking load of the two-layer reinforced composite beam is close to that of the three-layer reinforced beam,but the yield and ultimate loads are obviously improved.