玄武岩纤维复材筋增强自密实混凝土桥面板冲切性能试验

EXPERIMENTAL RESEARCH ON PUNCHING PERFORMANCE OF BFRP REINFORCED SELF-COMPACTING CONCRETE BRIDGE DECK

对6组尺寸为2 000 mm×1 800 mm×100 mm的1∶2比例缩尺桥面板模型进行冲切试验研究。分析不同筋材类型,不同混凝土基体材料及不同配筋率对桥面板冲切极限承载力、荷载-位移曲线、筋材应变、混凝土应变及裂缝形态的影响,对比不同文献中冲切极限承载理论值与试验值的差异。研究表明:在侧向约束作用下筋材在桥面板中的贡献较小,配筋率的降低对桥面板的极限承载力基本没有影响,但可以更大地发挥筋材在桥面板中的作用。筋材类型对桥面板的极限承载力,极限挠度及裂缝形态都有影响,但混凝土基体材料对桥面板的极限承载力和极限挠度的影响不大。各国现行标准对纤维增强材料筋增强混凝土结构冲切极限承载力的计算理论由于未考虑侧向边界约束条件下存在的压缩薄膜效应,严重低估了桥面板的冲切极限承载力。

Punching tests were conducted on six groups of 1 :2 scaled BFRP bars reinforced self-compacting concrete bridge deck slabs with dimensions of 2 000 mmx 1 800 mmx 100 mm to study the punching properties. The effects of types of bars, concrete matrix materials and reinforcement ratio on the ultimate bearing capacity, load-displacement curve, rebar strain, concrete strain and crack morphology of the bridge deck slabs were analyzed. The theoretical value of punching ultimate bearing capacity proposed by scholars were compared with the experimental values. The results indicated that the rebar had a little effect on the bridge deck slabs under lateral restraints and the decrease of the reinforcement ratio had no effect on the ultimate bearing capacity of the bridge deck slabs, but it could play a greater role of the reinforcement in the bridge deck slabs. The types of bars had a certain influence on the ultimate bearing capacity, the ultimate deflection and the crack morphology of the bridge deck slabs. However, the concrete matrix materials had little effect on the ultimate bearing capacity and the ultimate deflection of the bridge deck slabs. Existing codes of punching ultimate load capacity of FRP bars reinforced concrete structure seriously underestimate the punching ultimate bearing capacity of existing bridge deck slabs structure.