波形钢腹板PC组合箱梁疲劳损伤对抗弯承载能力的影响研究

制作两根体外预应力波形钢腹板简支PC组合箱梁,其中第一根梁进行静力全过程试验,另一根梁先进行疲劳试验直至波形钢腹板出现疲劳破坏后进行静力加载全过程试验;得到两根组合箱梁在弹塑性阶段的基本力学性能、典型疲劳损伤特征和疲劳前后的抗弯承载力。根据混凝土材料的S-N曲线和疲劳荷载的实际应力比,推导混凝土材料疲劳损伤后的强度退化规律、总结混凝土割线模量、极限应变的退化规律,据此得到混凝土材料疲劳损伤前、后的本构关系;基于截面M-N-Φ关系编制体外预应力简支组合箱梁抗弯承载力的非线性全过程分析程序,对两根试验梁进行全过程加载的模拟分析,理论与试验结果吻合良好;两者均表明波形钢腹板的疲劳损伤对组合箱梁抗弯承载力影响不大,但会大大降低结构的延性。

Study on the residual flexural capacity of composite box girders with corrugated steel webs after fatigue damage

The influence on the residual flexural capacity of simply supported composite box girders with corrugated steel webs after fatigue damage is investigated.Two model beams are built and a series of experimental tests are performed,including one static bending experiment for the first beam,one fatigue experiment followed by a residual bending experiment for the second beam.Some basic elastic-plastic mechanical performances,failure modes and the flexural ultimate capapcity are obtained from these tests.Based on these results and the fatigue properity of structural material,the deterioration of modulus,strength and ultimate strain are studied,and then the stress-strain relationship for concrete after fatigue damage is deduced.A nonlinear full-range-analysis program,which is based on the structural M-N-Φ relationship,is employed to simulate the experimental process,and the theoretical results and experimental results are in good agreement.All results show that the fatigue damage has slight effect on its flexural capacity but has a significant effect on its ductility.