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通过自行设计的装置测量了高温后粘结问题中的化学胶结力和摩擦系数,得出了它们随温度经历的变化规律。利用测得的基础参数定义了钢筋与混凝土界面的弹塑性库仑摩擦准则并将其植入有限元模型;采用面-面接触的接触单元模拟混凝土与钢筋界面的力学行为。模型通过对钢筋肋的显式离散实现了钢筋肋与混凝土间机械咬合作用的模拟。数值结果和试验数据的对比表明,该文提出的模型可以较好的模拟高温后带肋钢筋和混凝土之间的粘结滑移。最后,利用有限元模型对400℃温度经历拔出过程中的应力分布及裂缝的扩展进行了细致的研究。
Through the self-designed device, the chemical bonding force and the friction coefficient in the post-high-temperature bonding problem were measured, and their variation with temperature were obtained. The elastic-plastic Coulomb friction criterion of the interface between steel bar and concrete is defined based on the measured basic parameters and implanted into the finite element model. The mechanical behavior of the interface between concrete and steel bar is simulated by the contact unit of face-face contact. The model simulates the mechanical bite between steel rib and concrete through the explicit dispersion of steel rib. The comparison between numerical results and experimental data shows that the model proposed in this paper can simulate the bond slip between ribbed bars and concrete after high temperature. Finally, the finite element model was used to study the stress distribution and the crack propagation in the process of pulling out at 400 ℃.