循环荷载作用下预应力混凝土U型梁纵向裂缝试验研究

Experimental Study on Longitudinal Crack of Prestressed Concrete U-Beam Under Cyclic Loading

为了研究预应力钢筋混凝土U型梁行车道板处纵向裂缝对结构安全的影响,选择实际工程项目中标准梁段的一个节段进行循环加载试验.通过对试验梁节段进行1000万次的循环加载,分析了预应力混凝土U型梁行车道板纵向裂缝的发展及变化规律,并通过一定重复荷载作用后的静力试验研究了裂缝发展对结构安全的影响.结果表明,在整个循环加载过程中,结构位移、混凝土和钢筋的应变及行车道板的纵向裂缝均随着荷载循环次数的增加而增加,且前300万次循环加载变化较大,后期逐渐趋于平稳;钢筋的应力幅值较低,不会产生疲劳破坏;U型梁行车道板的寿命主要受纵向裂缝控制.

In order to study the influence of longitudinal crack on the safety of prestressed reinforced concrete u-beam deck,a section of a practical project was selected for cyclic load test.Through the method of 10 million times of cyclic loading on the test beam segment,the development and the variation law of longitudinal cracks of prestressed concrete U-beam deck were analyzed,and the influence of crack development on structural safety was studied through static test after certain cyclic loading.The results show that during the entire cyclic loading process,the structural displacement,the strain of the concrete and steel bars,and the longitudinal cracks of the deck increase with the number of load cycles.The change before 3 million cycles of loading is obvious but gradually stabilizes in the later stages;the stress amplitude of the steel bar is low,which will not cause fatigue damage;the life of the U-beam deck is mainly controlled by longitudinal cracks.