BFRP筋增强海水海砂混凝土梁的受弯性能

Flexural behavior of seawater sea-sand concrete(SWSSC)beams reinforced with BFRP bars

为推动BFRP筋海水海砂混凝土梁在实际工程中的应用,对9根配有BFRP筋、GFRP筋和钢筋的海水海砂混凝土梁进行四点弯曲试验。结果表明,增大配筋率或截面高度可提高承载力、减小挠度和裂缝宽度。相同配筋率下,直径小且分布更密的BFRP筋与混凝土的粘结性能更好,正常使用荷载和极限荷载下的裂缝宽度均减小,改善了梁的开裂性能,但其对承载力和挠度无显著影响。FRP筋海水海砂混凝土梁的极限承载力远高于钢筋混凝土梁,但其裂缝宽度和挠度均大于钢筋混凝土梁。经试验,大部分试验梁均能满足GB、ACI和CSA规范中规定的正常使用状态下的挠度和裂缝宽度要求。ACI规范对BFRP筋海水海砂混凝土梁正截面承载力的设计偏保守,最新实施的GB规范中规定的FRP筋受弯构件的正截面承载力计算公式对BFRP筋海水海砂混凝土梁有较好的适用性。

In order to promote the application of SWSSC beams reinforced with BFRP bars in actual projects,nine SWSSC beams reinforced with BFRP,GFRP and steel bars under four-point bending loading were tested.The increase of the reinforcement ratio or section height can improve the bearing capacity,reducing the deflection and crack width.The smaller diameter BFRP bars with similar reinforcement ratio have better bonding performance with concrete,which improves the cracking performance of the beam and reduces the crack width under normal service load and ultimate load,but it has no significant effect on the bearing capacity and deflection.The ultimate bearing capacity of SWSSC beams reinforced with FRP bars is much higher than that of reinforced concrete beams,but the crack width and deflection of SWSSC beams reinforced with BFRP bars are larger than that of reinforced concrete beams.According to the codes ACI,CSA and GB,most of the test beams can meet the requirements of deflection and crack width under normal service conditions.ACI specification is conservative in the design of normal section bearing capacity of BFRP bars reinforced SWSSC beams.The calculation formula of normal section bearing capacity of FRP bar flexural member stipulated in the latest GB code has good applicability to BFRP bar reinforced SWSSC beam.