大型钢管插入式基础裂缝产生机理及影响参数研究

Study on Crack Generation Mechanism and Influencing Parameters of Large Steel Pipe Inserted Foundation

目的研究大型钢管插入式基础在上拔工况下的裂缝产生机理及影响规律,寻求最佳设计参数。方法基于扩展有限元与内聚力界面接触,建立三维非线性有限元模型,首先通过对比无锚板、单锚板与双锚板构件裂缝扩展过程云图,分析裂缝产生机理,再通过优化设计配筋方案和位置系数,探讨大型钢管插入式基础的裂缝密度和裂尖应力强度因子的变化规律。结果锚固板的增加会导致基础混凝土开裂,位置系数的取值会影响基础裂缝密度;当配筋率为1.76%时,在钢管外侧设置环状排列纵筋能明显减小锚固板处由于应力集中产生的混凝土开裂;当位置系数为0.33时钢管外侧混凝土的裂尖应力强度因子较小,使得基础构件在满足经济性的同时不会由于钢管外侧混凝土过薄而过早产生开裂。结论改变基础配筋方式、选取合理的配筋方案以及位置系数能够有效地减少钢管插入式基础裂缝的生成。

To study the crack mechanism and influencing parameters of the large steel-tube-inserted foundation under the uplift condition,and seek the best design parameters,The three-dimensional finite element model was established based on the extended finite element and the cohesive-zone model.The analysis results show that the increase of anchor plate will lead to concrete cracking,and the value of position coefficient will affect the Cracking density.In view of this,the Cracking density and the stress intensity factors of large steel-tube-inserted foundation are discussed by optimizing the reinforcement scheme and position coefficient.The results show that the concrete cracking caused by stress concentration at the anchor plate can be obviously reduced by setting ring-shaped longitudinal bars outside the steel tube;When the position coefficient is 0.33,the stress intensity factors of the concrete outside the steel tube is smaller,so that the foundation components will not be cracked prematurely due to the thin concrete outside the steel tube while meeting the economic requirements.It can be concluded that changing the reinforcement mode of the column,selecting the reasonable reinforcement coefficient and selecting the reasonable position coefficient can effectively reduce the crack generation of the steel pipe inserted foundation.