筋材类型和混凝土强度协同效应对梁构件受弯性能影响研究

Study on Synergistic Effect of Reinforcement Type and Concrete Strength on Flexural Performance of Beam Components

摘要:

为研究筋材类型（GFRP筋/钢筋）和混凝土强度（UHPC/C50）对梁受弯性能的影响，设计、制作了4根试验梁（GU、GC、SU和SC）进行试验，分析不同材料组合下梁的破坏模式、荷载-挠度曲线、裂缝发展规律和延性。结果表明：钢筋试件呈钢筋屈服、受压区混凝土压溃的延性破坏，荷载-挠度曲线存在明显屈服平台，而GFRP筋试件表现为GFRP筋未拉断、受压区混凝土压溃的脆性破坏，荷载-挠度曲线呈双线型，裂缝发展更快，分布更密集，延性相对较差；不同材料组合下，GFRP筋与UHPC组合的试件GU能够有效发挥材料的高抗拉和高抗压性能，其极限承载力较SU试件提升46%，较GC试件提升55%，较SC试件提升52%；此外，UHPC试件的初裂名义应力可达7.5~8.0 MPa，远高于C50试件的1.5~2.0 MPa，能显著提升试件初裂荷载并延缓裂缝扩展。

Abstract:

To study the effects of reinforcement type (GFRP bar/steel bar) and concrete strength (UHPC/C50) on the flexural performance of beams, four test beams (GU, GC, SU and SC) are designed and fabricated for the experiments. The failure mode, load - deflection curve, crack development law and ductility of beams under different material combinations are analyzed. The result shows that the steel bar specimens exhibit the ductile failure of concrete collapse in the yield and compression zones of the steel bars. There is a clear yield plateau in the load deflection curve. And the GFRP bar specimens show brittle failure where the GFRP bar is not broken and the concrete in the compression zone is crushed. The load - deflection curve is in a bilinear shape. And the cracks develop more rapidly and are distributed more densely with the poor ductility. Under different material combinations, the specimens GU composed of GFRP bars and UHPC can effectively exert the high tensile and compressive strength of the materials. The ultimate bearing capacity of GU has increased by 46% compared to SU, 55% compared to GC, and 52% compared to SC. In addition, the initial crack nominal stress of UHPC specimens can reach 7.5 to 8.0 MPa, which is much higher than 1.5 to 2.0 MPa of C50 specimens, which can significantly increase the initial crack load of the specimens and delay crack propagation.