基于XFEM的预应力混凝土梁裂纹扩展研究

XFEM-based Study on Crack Extension of Prestressed Concrete Beams

混凝土开裂多是由于混凝土材料中拉应力超过抗拉极限引起的,在工程中常用预应力来增强混凝土整体的抗拉性能。为了研究预应力的施加如何阻止混凝土中的裂纹扩展,基于ANSYS仿真建立有、无预应力的预制裂纹混凝土梁的扩展有限元模型,在相同的荷载施加条件下进行裂纹扩展计算。研究发现预应力的施加可以有效提高混凝土开裂的临界荷载且加剧混凝土开裂的突然性;同时,还会改变裂纹扩展模式,使裂纹随着荷载的增加发生逐段的突变扩展,区别于无预应力混凝土梁中的裂纹连续扩展;在相同荷载作用下,相比无预应力混凝土,预应力的施加显著降低了底部裂纹的扩展长度及裂纹最大张开宽度,有效的控制了裂纹扩展。

Concrete cracking is mostly caused by the tensile stress that exceeds the ultimate tensile strength of concrete material,and prestressing is commonly used to enhance the overall tensile performance of concrete in engineering.In order to investigate how the prestress affects the crack extension in concrete,an ANSYS-based finite element model of concrete beams with prefabricated crack,with and without prestress,was established,and the crack extension was calculated under the same loading conditions.It is found that the prestressing force can effectively increase the critical load of concrete cracking and intensify the abruptness of cracking;meanwhile,prestressing force changes the crack extension pattern,causing the crack to expand abruptly segment by segment with the increase of load,which is different from the continuous crack extension in unprestressed concrete beams;Under the same load condition,the prestress significantly reduces the crack extension length at the bottom and the maximum crack opening width,and the crack extension is effectively controlled.