UHPC华夫桥面板抗弯性能试验及有限元分析

Test and finite element analysis on bending performance of UHPC Waffle deck panel

为研究超高性能混凝土(UHPC)华夫桥面板的横桥向抗弯性能,首先开展了4个横肋的足尺条带模型抗弯性能静力试验;然后采用ABAQUS有限元软件建立了试件非线性有限元模型,模型中考虑了材料非线性和几何非线性,其中对UHPC考虑了混凝土损伤塑性模型等,并利用该有限元模型模拟试验全过程;最后通过有限元参数分析明确主要设计参数对UHPC华夫桥面板横向抗弯性能的影响规律,包括横肋纵向配筋率(钢筋直径)、横肋高度、顶板高度以及横肋间距等。研究结果表明:正弯矩作用下试件的受弯破坏过程包含线弹性阶段、裂缝开展阶段和屈服阶段;华夫桥面板横肋底面出现横向裂缝导致结构刚度第1次下降,随着裂缝的发展,截面内力重分布使得底部纵筋应力持续增大直至屈服,导致刚度出现第2次下降,裂缝进一步向上开展逼近翼缘板顶部,由于受拉区充分发展导致顶板纵筋受拉屈服,刚度出现第3次下降,结构刚度严重衰减,试件承载力接近极限,趋于破坏;有限元计算结果与试验结果吻合良好;通过参数分析发现,增加纵筋配筋率(钢筋直径)对初裂荷载影响很小,但可有效限制裂缝的发展;增加肋高对初裂荷载有一定的提高作用,还可提高矮肋T梁的初始刚度、开裂后刚度以及极限承载力;增加顶板高度也可起到同样的效果,但肋高对初始刚度的提高效率是顶板的5.4倍;增加横肋间距可提高单根横肋的初始刚度、开裂后刚度以及极限承载力,但削弱了横向整体刚度。

In order to study the transversal bending performance of UHPC Waffle deck panel, four specimens with transverse rib in full scale were firstly carried out for bending performance static test. Then nonlinear finite element models of specimens were established by using the finite element software ABAQUS, in which the material nonlinearity, geometric nonlinearity and plastic damage model of concrete for UHPC were considered, and the whole test process was simulated by using the finite element model. Finally, the influence of primary parameters on the transversal bending performance of UHPC Waffle deck panel was ascertained by parameter analysis, which included the longitudinal reinforcement ratio of transverse rib （the diameter of reinforcement）, the height of transverse rib, the height of top plane and the spacing of transverse rib. The results show that specimens undergo following typical stages under the action of positive bending moment, linear elastic stage, crack-developing stage and yield stage. Transversal cracks appear at the bottom of transverse rib, which lead to the first decrease of structural stiffness. With the development of cracks, the redistribution of internal forces results in a continuous rise of stress in the reinforcement until it＇s yielding, which causes a second drop of stiffness. Then cracks propagates further upward to the bottom of flange, because the tensile zone develops to the extreme point leading the upper reinforcement to yield, the stiffness of specimen decreases rapidly, which is the third decline of stiffness. The bearing capacity of specimen is close to the extreme and tends to be destroyed. The finite element results are consistent with those from experiments. Parameter analysis shows that the influence of the longitudinal reinforcement ratio （the diameter of reinforcement） on the initial cracking load is negligible, whereas the development of cracks can be restricted effectively. The increase of rib height can not only show some inhibitory effect on the initial cracking load, but also can enhance the initial stiffness, the stiffness after cracking and the ultimate bearing capacity of T-beam. Increasing the height of top plane could also achieve a similar effect, but improvement efficiency of initial stiffness by increasing the rib height is 5.4 times of that by increasing the top plane height. The increase of rib spacing can improve initial stiffness, the stiffness after cracking as well as ultimate bearing capacity of a single transversal rib, but the global stiffness in transversal direction is impaired. 8 tabs, 19 figs, 26 refs.