服役后T梁破坏性试验全过程仿真分析

Simulation Analysis on Destructive Test Full Process for T-beams After Service

为准确模拟服役后T梁的初始裂缝对T梁实际受力过程的影响,确定结构模拟参数及初始裂缝的模拟方法和模拟值,选取了同一跨径不同初始病害等级的两片进行了单梁的破坏性加载试验,详细记录了T梁的初始裂缝分布形态及加载破坏裂缝开展过程,通过建立Abaqus空间实体有限元模型,进行全过程仿真分析研究;研究表明,采用实体单元模拟混凝土,塑性损伤本构模型、Lubliner屈服准则与非关联的流动法则来描述混凝土的塑性性能,桁架单元模拟钢筋,理想弹塑性随动强化模型,Von-Mises来体现钢筋的塑性性能,并利用加载T梁的混凝土进行钻芯取样通过力学试验确定的实际结构参数对混凝土、钢筋本构模型进行修正后,模型能够准确地模拟T梁的破坏性试验全过程;混凝土采用Kent-Park模型构建压应力-应变关系、采用过镇海模型模拟受拉应力-应变关系,选取损伤参数-塑性损伤模型模拟混凝土裂缝扩展与试验T梁实测开裂规律基本吻合;通过预加载开裂的方式,确定初始裂缝,并以实测最大裂缝长度的7/6倍来作为初始裂缝的模拟值,能够较准确地模拟结构的初始损伤力学状态。

To accurately simulate the influence of initial cracks on the actual stress process of T-beam after service,the structural simulation parameters and the simulation method and value of initial cracks were determined.Two beams with same span and different initial disease levels were selected for destructive loading tests on a single beam.The initial crack distribution morphology and loading failure crack development process of T-beam were recorded in detail.By establishing the ABAQUS spatial solid finite element model,the entire process simulation analysis was conducted.The result indicates that by using solid units to simulate concrete,the plastic damage constitutive model,Lubliner yield criterion,and non-correlated flow rule were used to describe the plastic properties of concrete.The truss element simulated the steel bars,and the ideal elastic-plastic dynamic strengthening model and Von-Mises were used to reflect the plastic performance of the steel bars.By using the concrete loaded with T-beams for core drilling and sampling,the actual structural parameters determined through mechanical tests were used to modify the constitutive models of concrete and steel bars.The model can accurately simulate the entire destructive test process of T-beam.The Kent-Park model was used to construct the compressive stress-strain relation for concrete.The Guo Zhenhai model was used to simulate the tensile stress-strain relation,and the damage parameter plastic damage model was selected to simulate the crack propagation of concrete,which was basically consistent with the actual cracking rule.The initial crack was determined using preloading cracking,and the simulated value of initial crack was 7/6 times of the measured maximum crack length,which can accurately simulate the initial damage mechanics state of the structure.